@prefix vivo: . @prefix edm: . @prefix ns0: . @prefix dcterms: . @prefix skos: . vivo:departmentOrSchool "Medicine, Faculty of"@en, "Pathology and Laboratory Medicine, Department of"@en ; edm:dataProvider "DSpace"@en ; ns0:degreeCampus "UBCV"@en ; dcterms:creator "Kennedy, Susan Marguerite"@en ; dcterms:issued "2010-06-12T16:03:27Z"@en, "1984"@en ; vivo:relatedDegree "Doctor of Philosophy - PhD"@en ; ns0:degreeGrantor "University of British Columbia"@en ; dcterms:description """Previous studies which identified inflammation in the peripheral airways of the lung as a potentially reversible early component in the development of chronic airflow obstruction led to the investigations reported here concerning the possible early diagnosis of airway inflammation using gallium-67; the relationship between airway inflammation, increased permeability and hyper-reactivity; and peripheral airway changes seen in persons exposed to mineral dust and fume contrasted with those seen in cigarette smokers. Aerosolized radiogallium was administered in two studies, first to guinea pigs exposed to cigarette smoke and then to human smokers and the retention and clearance compared to that in non-smoking controls, and in the guinea pigs, to the degree of polymorphonuclear infiltration of the airways. The results revealed no difference in clearance between smokers and non-smokers and prolonged retention of the tracer in the lungs. Autoradiography in guinea pigs and humans suggested that the gallium was taken up by macrophages, not by polymorphonuclear cells. This suggests that the use of radiogallium to mark polymorphonuclear infiltration is not useful. Increased respiratory epithelial permeability in human smokers was demonstrated by following the disappearance from the lungs of 99m technetium labelled diethylenetriame penta acetate. However, no relationship was seen between increased permeability and airway reactivity as measured by the degree of airflow obstruction following inhalation of increasing doses of histamine. This suggests that although airway inflammation may result in increased airway permeability, this does not directly induce hyper-reactivity. Finally, peripheral airway structural and functional changes were compared in two groups of patients undergoing lung resection: one with occupational mineral dust or fume exposure and the other, not exposed to dust or fume, individually matched to the first group for age and smoking history. The results indicated increased airflow obstruction in the exposed group and excess fibrous connective tissue deposition and goblet cell metaplasia in their peripheral airways, particularly in those patients exposed to mineral dust and fume in a non-mining occupation. No increase was seen in degree of inflammatory cell infiltration of the airway walls. These results suggest that the peripheral airway response to mineral dust or fume differs qualitatively from the response to cigarette smoke."""@en ; edm:aggregatedCHO "https://circle.library.ubc.ca/rest/handle/2429/25592?expand=metadata"@en ; skos:note "AIRWAY RESPONSE TO INHALED AIR POLLUTANTS -CIGARETTE SMOKE & INDUSTRIAL DUST & FUME By SUSAN MARGUERITE KENNEDY A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY i n THE FACULTY OF GRADUATE STUDIES DEPARTMENT OF PATHOLOGY We a c c e p t t h i s t h e s i s as conforming to the r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA March 1984 (Q\\ Susan M a r g u e r i t e Kennedy^ 1 9 8 4 I n p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r an a d v a n c e d d e g r e e a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e t h a t t h e L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e a n d s t u d y . I f u r t h e r a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by t h e h e a d o f my d e p a r t m e n t o r by h i s o r h e r r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l n o t be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . D e p a r t m e n t o f P a t h o l o g y The U n i v e r s i t y o f B r i t i s h C o l u m b i a 2075 W e s b r o o k P l a c e V a n c o u v e r , C a n a d a V6T 1W5 D a t e 8 March 1984 •7Q ^ - i i -ABSTRACT P r e v i o u s s t u d i e s which i d e n t i f i e d i n f l a m m a t i o n i n the p e r i p h e r a l a i r w a y s o f the l u n g as a p o t e n t i a l l y r e v e r s i b l e e a r l y component i n the development o f c h r o n i c a i r f l o w o b s t r u c t i o n l e d to the i n v e s t i g a t i o n s r e p o r t e d here c o n c e r n i n g the p o s s i b l e e a r l y d i a g n o s i s o f airway i n f l a m m a t i o n u s i n g gallium-67; the r e l a t i o n s h i p between airway i n f l a m m a t i o n , i n c r e a s e d p e r m e a b i l i t y and h y p e r - r e a c t i v i t y ; and p e r i p h e r a l airway changes seen i n persons exposed to m i n e r a l dust and fume c o n t r a s t e d w i t h those seen i n c i g a r e t t e smokers. A e r o s o l i z e d r a d i o g a l l i u m was a d m i n i s t e r e d i n two s t u d i e s , f i r s t to guinea p i g s exposed to c i g a r e t t e smoke and then to human smokers and the r e t e n t i o n and c l e a r a n c e compared to t h a t i n non-smoking c o n t r o l s , and i n the guinea p i g s , to the degree o f polymorphonuclear i n f i l t r a t i o n o f the a i r w a y s . The r e s u l t s r e v e a l e d no d i f f e r e n c e i n c l e a r a n c e between smokers and non-smokers and pr o l o n g e d r e t e n t i o n o f the t r a c e r i n the l u n g s . A u t o r a d i o g r a p h y i n guinea p i g s and humans suggested t h a t the g a l l i u m was taken up by macrophages, not by polymorphonuclear c e l l s . T h i s suggests t h a t the use o f r a d i o g a l l i u m to mark polymorphonuclear i n f i l t r a t i o n i s not u s e f u l . I n c r e a s e d r e s p i r a t o r y e p i t h e l i a l p e r m e a b i l i t y i n human smokers was demonstrated by f o l l o w i n g the d i s a p p e a r a n c e from the lungs o f 99m t e c h n e t i u m l a b e l l e d d i e t h y l e n e t r i a m e penta a c e t a t e . However, no r e l a t i o n s h i p was seen between i n c r e a s e d p e r m e a b i l i t y and airway r e a c t i v i t y as measured by the degree o f a i r f l o w o b s t r u c t i o n f o l l o w i n g i n h a l a t i o n o f i n c r e a s i n g doses o f h i s t a m i n e . T h i s s u g g e s t s t h a t a l t h o u g h airway i n f l a m m a t i o n may r e s u l t i n i n c r e a s e d airway p e r m e a b i l i t y , t h i s does not d i r e c t l y i n d u c e h y p e r - r e a c t i v i t y . F i n a l l y , p e r i p h e r a l airway s t r u c t u r a l and f u n c t i o n a l changes were compared i n two groups o f p a t i e n t s u n d e r g o i n g l u n g r e s e c t i o n : one w i t h o c c u p a t i o n a l m i n e r a l dust o r fume exposure and the o t h e r , not exposed to dust o r fume, i n d i v i d u a l l y matched to the f i r s t group f o r age and smoking h i s t o r y . The r e s u l t s i n d i c a t e d i n c r e a s e d a i r f l o w o b s t r u c t i o n i n the exposed group and excess f i b r o u s c o n n e c t i v e t i s s u e d e p o s i t i o n and g o b l e t c e l l m e t a p l a s i a i n t h e i r p e r i p h e r a l a i r w a y s , p a r t i c u l a r l y i n those p a t i e n t s exposed to m i n e r a l dust and fume i n a non-mining o c c u p a t i o n . No i n c r e a s e was seen i n degree o f in f l a m m a t o r y c e l l i n f i l t r a t i o n o f the airway w a l l s . These r e s u l t s suggest t h a t the p e r i p h e r a l airway response to m i n e r a l dust o r fume d i f f e r s q u a l i t a t i v e l y from the response to c i g a r e t t e smoke. - i v -TABLE OF CONTENTS Abstract i i L i s t of Tables v L i s t of Figures v i Acknowledgements v i i I. Introduction 1 References 3 I I . Deposition of Inhaled Pollutants - Physical Determinants 4 References 17 I I I . Lung Clearance Mechanisms 21 References 39 IV. The Lung Response and the Inflanvmatory Process 47 References 59 V. An Investigation of Small Airway Inflammation Using Ga-67 as a Marker of Inflammatory C e l l s 68 References 93 VI. Airway Mucosal Permeability and Re a c t i v i t y 111 References 145 VII. Small Airway Structure and Function in Persons Exposed to Mineral Dust and Fume - Compared to Cigarette Smokers 164 References 183 VIII. Summary and Concluding Comments 198 LIST OF TABLES I. Ga-67 blood l e v e l s at 12 hrs post exposure 102 I I . Ga-67 a c t i v i t y of lungs and trachea of Ga-67 exposed guinea pigs 108 I I I . Subject c h a r a c t e r i s t i c s and pulmonary function -Study 1 161 IV. Permeability and Re a c t i v i t y data - Study 1 162 V. Subject c h a r a c t e r i s t i c s and antigen response -Study 2 163 VI. Permeability data - Study 2 163 VII. Exposure h i s t o r i e s 187 VIII. Pulmonary Function - exposed workers compared to controls 188 IX. Miners compared to controls 189 X. Dust/fume compared to controls 190 XI. Small airways pathology - exposed vs controls 191 XII. Small airway pathology 192 XII. Radiology 193 - v i -LIST OF FIGURES 1. Ga-67 a c t i v i t y in lungs of control and smoke-exposed animals 103 2. Inflammation scores f or cartilagenous and non-cartilagenous airways . 104 3. Cartilagenous airway from smoke-exposed animal 105 4. Ga-67 a c t i v i t y i n human non-smokers 107 5. Ga-67 A c t i v i t y i n human smokers 107 6. Autoradiographs from lung sections from guinea pigs exposed to smoke 109 7. Autoradiographs from human subject 110 8. Deposition pattern of aerosolized Tc-DTPA in lungs -smokers and non-smokers 156 9. Disappearance of Tc-DTPA from lungs 157 10. Appearance of Tc-DTPA in blood 158 11. Individual histamine dose-response curves 159 12. Deposition pattern of aerosolized Tc-DTPA in cedar asthma patients 160 13. Small airway les i o n s seen in workers exposed to dust and fume 195 14. S i l i c o t i c l e s i o n seen in miners 197 - v i i -ACKNOWLEDGEMENTS Dr. J.C. Hogg acted as my primary research supervisor throughout t h i s p r o j e c t and h i s suggestions, advice and encouragement provided the basis on which I was able to c a r r y out t h i s work. My since r e a p p r e c i a t i o n i s extended to him. I am a l s o g r a t e f u l to Dr. P.D. Pare who taught me pulmonary physiology, allowed me to f u r t h e r h i s p e r m e a b i l i t y and r e a c t i v i t y s t u d i e s , and provided v a l u a b l e c r i t i c i s m and suggestions throughout my work. Many thanks a l s o to Dr. W i l l i a m Thurlbeck who provided u s e f u l comments and suggestions. Dr. David Walker gave me a great deal of personal encouragement and support as w e l l as much a s s i s t a n c e w i t h morphology and autoradiography. My thanks to him f o r a l l h i s care and advice. Dr. C.E. Slonecker of the Anatomy Department provided the i n i t i a l equipment, i n f o r m a t i o n , and feedback which allowed me to c a r r y out the g a l l i u m autoradiography. Dr. B i l l H u l b ert, now of the U n i v e r s i t y of A l b e r t a , taught me guinea p i g surgery and provided u s e f u l comments and feedback regarding airway p e r m e a b i l i t y and r e a c t i v i t y . Thanks a l s o to Dr. A. Belzberg, f o r h i s as s i s t a n c e and advice w i t h respect to ra d i o i s o t o p e imaging, to Dr. R.G. Pitman f o r reading the radiographs from a l l the p a t i e n t s i n the s t r u c t u r e - f u n c t i o n c o r r e l a t i o n study, and to Dr. J.L. Wright f o r teaching me to grade small airway pathology and f o r doing the membranous bronchiole grading f o r many of the p a t i e n t s . I am a l s o extremely a p p r e c i a t i v e f o r the expert t e c h n i c a l a s s i s t a n c e provided by the f o l l o w i n g persons: C a r i n P i h l f o r - x i -photography, Catherine Coppin and Louise Brooks f o r a s s i s t a n c e w i t h pulmonary f u n c t i o n t e s t i n g , a l l the t e c h n i c a l s t a f f of St. Paul's H o s p i t a l nuclear medicine department f o r making up isotope s o l u t i o n s and g e n e r a l l y keeping me on t r a c k i n t h e i r department, the h i s t o l o g y s t a f f of St. Paul's f o r p r o v i d i n g p a r a f f i n s e c t i o n s . Barry Wiggs f o r w r i t i n g i n v a l u a b l e computer programmes and showing me how to do a l l the computer a n a l y s i s , and Kathy Beckner f o r the most p a i n s t a k i n g but necessary task of a l l , t y p i n g and r e - t y p i n g the manuscript. - 1 -I. INTRODUCTION A s i g n i f i c a n t amount o f r e s p i r a t o r y d i s e a s e and m o r t a l i t y i n our s o c i e t y can be a c c o u n t e d f o r by the b r e a t h i n g o f d i r t y a i r . T h i s i s t r u e b o t h today and i n the p a s t . As e a r l y as the s i x t e e n t h c e n t u r y , G e o r g i u s A g r i c o l a r e c o g n i z e d mine d u s t as a cause o f much l u n g d i s e a s e and d e a t h among m i n e r s i n the H a r t z mounta ins (1). Tobacco smoking became common i n the wes t e rn hemisphere i n the l a t e f i f t e e n t h c e n t u r y but the h e a l t h e f f e c t s o n l y began to be a p p r e c i a t e d by the end o f the n i n e t e e n t h c e n t u r y ( 2 ) . Today , a l t h o u g h o u r r e c o g n i t i o n and u n d e r s t a n d i n g o f the p rob l em o f i n h a l e d p o l l u t a n t s and how they p roduce d i s e a s e has i n c r e a s e d g r e a t l y , the magn i tude o f the p r o b l e m rema ins as h i g h , i f not h i g h e r , t han i n c e n t u r i e s p a s t . P r e v e n t i o n s t r a t e g i e s i n p l a c e today i n c l u d e smoking e d u c a t i o n c ampa igns , wh i ch may be e f f e c t i v e i n r e d u c i n g the number o f t o b a c c o smokers , and l e g i s l a t i v e c o n t r o l s p l a c e d on the ext reme o c c u p a t i o n a l e x p o s u r e s p r e v i o u s l y common i n many m i n e s , m i l l s and f a c t o r i e s . However , the p o t e n t i a l f o r exposu re t o h a r m f u l agen ts i n the a i r r e m a i n s . The re a re a p p r o x i m a t e l y 10,000 new c h e m i c a l s e n t e r i n g c o m m e r c i a l and i n d u s t r i a l use e ve r y y ea r (3) many o f wh i ch a re r e s p i r a b l e . The number o f e n v i r o n m e n t a l / o c c u p a t i o n a l agen t s a s s o c i a t e d w i t h r e s p i r a t o r y h y p e r s e n s i t i v i t y o r o t h e r adve r se r e a c t i o n s , i s a l s o i n c r e a s i n g . In c o n j u n c t i o n w i t h t h i s i s a t endency on the p a r t o f p o l i c y - m a k e r s to r e l a x e n v i r o n m e n t a l s t a n d a r d s i n - 2 -f a v o u r o f immediate economic c o n c e r n s . T o g e t h e r , t he se f a c t o r s s u g g e s t t h a t r e s p i r a t o r y d i s e a s e r e l a t e d t o a i r b o r n e p o l l u t a n t s may no t d e c l i n e i n d i r e c t p r o p o r t i o n t o a d e c r e a s e i n t o b a c c o c o n s u m p t i o n . The l u n g , b e i n g i n c o n s t a n t c o n t a c t w i t h the e n v i r o n m e n t , has d e v e l o p e d an i m p r e s s i v e d e f e n s i v e armament by wh i ch t o m a i n t a i n i t s e q u i l i b r i u m , r e p a i r damage, and r i d i t s e l f o f i n h a l e d t o x i c o r i r r i t a n t s u b s t a n c e s . These d e f e n s i v e mechanisms a re g e n e r a l l y n o n - s p e c i f i c but t h e i r r e l a t i v e impor t ance as w e l l as t h e i r d u r a t i o n , i n t e n s i t y , and u l t i m a t e s u c c e s s a re dependent bo th on c h a r a c t e r i s t i c s o f the exposu re and on c e r t a i n h o s t f a c t o r s . The i n t r o d u c t o r y s e c t i o n s o f t h i s r e p o r t ( C h a p t e r s I I , I I I and IV) w i l l r e v i e w the exposu re c h a r a c t e r i s t i c s wh ich i n f l u e n c e l u n g r e s p o n s e , the n a t u r e o f the h o s t d e f e n c e mechan isms , and the p a t t e r n s o f r eponse wh i ch may r e s u l t i n damage t o l u n g t i s s u e . The s p e c i f i c i n v e s t i g a t i o n s d e s c r i b e d i n the main body o f t he r e p o r t ( C h a p t e r s V , V I and V I I ) were d i r e c t e d s p e c i f i c a l l y a t the a i rway r e s p o n s e t o i n h a l e d p o l l u t a n t s . Much o f the work d e s c r i b e d r e l a t e s t o the e f f e c t s o f t o b a c c o smoke i n h a l a t i o n w i t h some a d d i t i o n a l d a t a on exposu re t o m i n e r a l d u s t s o r fumes and t o i n h a l a t i o n o f c e d a r d u s t . T h i s work has f o c u s s e d p a r t i c u l a r l y on the i n f l a m m a t o r y r e s p o n s e : t he d e t e r m i n a t i o n o f e a r l y a i rway i n f l a m m a t i o n b e f o r e i r r e v e r s i b l e t i s s u e damage has o c c u r r e d , the a s s o c i a t i o n between a i rway i n f l a m m a t i o n , p e r m e a b i l i t y , and r e a c t i v i t y ; and the m o r p h o l o g i c i d e n t i f i c a t i o n o f i n f l a m m a t i o n and i t s s e q u e l a e i n p e r i p h e r a l a i rways and i t s r e l a t i o n s h i p t o f u n c t i o n a l a b n o r m a l i t i e s . - 3 -REFERENCES - CHAPTER I 1. Morgan WKC, Sea ton A : O c c u p a t i o n a l Lung D i s e a s e s . P h i l a d e l p h i a : W B S a u n d e r s , 1975 2. B u i s t S, D u c i c S: Smok ing . E v a l u a t i o n o f S t u d i e s wh ich have d e m o n s t r a t e d pu lmonary f u n c t i o n changes . I n : Macklem PT , Pe rmut t S, e d s , The Lung i n the T r a n s i t i o n Between H e a l t h and D i s e a s e . New Y o r k : M a r c e l Dekke r , 1979 3. H inds WC: The l u n g and the e n v i r o n m e n t . Sem Resp Med 1980 ; 1:197-210 - 4 -I I . D e p o s i t i o n o f i n h a l e d p o l l u t a n t s - p h y s i c a l d e t e r m i n a n t s Con taminan t s i n the a tmosphere a re p r e s e n t i n v a r i o u s f o r m s . These can be c l a s s i f i e d as d u s t s , m i s t s , fumes , g a s e s , and v a p o u r s . The te rm a e r o s o l i s used t o r e f e r t o a i r b o r n e p a r t i c l e s ( s o l i d o r l i q u i d ) suspended i n a i r , and thus i n c l u d e s b o t h d u s t and m i s t . These p a r t i c l e s can v a r y i n s i z e f rom e x t r e m e l y s m a l l n u c l e i (< O.OOlu) t o c o a r s e m i n e r a l d u s t s (100 u o r m o r e ) . Fumes a re made up o f m e t a l o x i d e s wh i ch a re c r e a t e d when m e t a l s a re h e a t e d above t h e i r m e l t i n g p o i n t and a re g e n e r a l l y s u b m i c r o n i c when formed a l t h o u g h they may undergo s i g n i f i c a n t a g g r e g a t i o n . Vapours and gases a re n o n - p a r t i c u l a t e m o l e c u l a r s p e c i e s , the f o rmer b e i n g n o r m a l l y l i q u i d . The s i z e range o f suspended p a r t i c u l a t e s g e n e r a l l y e n c o u n t e r e d i n the o u t d o o r env i ronment i s f r om 0.01 u n u c l e i t o 20 p. a e r o s o l s w i t h l a r g e r p a r t i c l e s g e n e r a l l y s e t t l i n g ou t ( 1 ) . I n h a l a t i o n o f a t m o s p h e r i c c o n t a m i n a n t s does no t imp l y 100% r e t e n t i o n . In f a c t c o n s i d e r a b l e v a r i a t i o n e x i s t s f o r the amount and l o c a t i o n o f d e p o s i t i o n wh ich depends on many p h y s i c a l f a c t o r s . H e a l t h e f f e c t s as a consequence o f d e p o s i t i o n a re then modu l a t ed no t o n l y by d e p o s i t i o n but a l s o by the c l e a r a n c e and d e f e n s e f a c t o r s wh i ch w i l l be d i s c u s s e d i n the f o l l o w i n g c h a p t e r . 1. I n h a l a t i o n and a b s o r p t i o n o f gases and vapou r s The no rma l f u n c t i o n i n g o f t he r e s p i r a t o r y t r a c t r e q u i r e s r a p i d _ 5 -and e f f i c i e n t exchange and a b s o r p t i o n / d e s o r p t i o n o f 0^ and CO^. These p r o c e s s e s a re gove rned by p h y s i c a l laws wh i ch a re g e n e r a l l y a p p l i c a b l e t o the b e h a v i o u r o f any gaseous s o l u t e s . These laws g o v e r n the p a t t e r n o f v e n t i l a t i o n , o r the t r a n s p o r t o f i n s p i r e d gas i n t o t he v a r i o u s l u n g components , and d i f f u s i o n , o r the t r a n s f e r o f the gas i n t o the t i s s u e . The f a c t o r s wh i ch i n f l u e n c e the norma l v e n t i l a t o r y p a t t e r n i n c l u d e s t a r t i n g l u n g volumes and r e s i s t a n c e f a c t o r s wh i ch may be r e l a t e d t o p r o p e r t i e s o f the gas ( e g . d e n s i t y , v i s c o s i t y ) and p r o p e r t i e s o f the l u n g s ( e g . c o m p l i a n c e , o b s t r u c t i o n ) . D i f f u s i o n t h r o u g h t i s s u e i s d e t e r m i n e d by the a v a i l a b l e s u r f a c e a r e a , the t i s s u e t h i c k n e s s , the d i f f e r e n c e i n p a r t i a l p r e s s u r e o f the gas between the two s i d e s o f the t i s s u e , and the gas s o l u b i l i t y and m o l e c u l a r w e i g h t . These f a c t o r s have been w e l l d e s c r i b e d f o r norma l r e s p i r a t i o n ( 2 , 3 ) . The d i s t r i b u t i o n and up take o f t o x i c gases and vapou r s depend on t h e s e same f a c t o r s . However , the s i t e o f a c t i o n and amount o f up take a re p a r t i c u l a r l y i n f l u e n c e d by s o l u b i l i t y , t ime and s u r f a c e a r e a a v a i l a b l e f o r c o n t a c t , c o n c e n t r a t i o n o f the gas i n the a i r , and b u f f e r i n g c a p a c i t y o f the mucus. T h e o r e t i c a l c a l c u l a t i o n o f the amount o f a b s o r p t i o n wou ld have t o i n c l u d e c a l c u l a t i o n s f o r f o u r t r a n s f e r p r o c e s s e s : mass t r a n s p o r t d u r i n g i n h a l a t i o n , t r a n s p o r t t h r o u g h the r a d i a l c o n c e n t r a t i o n g r a d i e n t i n the a i r w a y s , mass t r a n s f e r f rom gas t o l i q u i d , and d i f f u s i o n t h rough o r r e a c t i o n w i t h l i q u i d ( 1 ) . Such c a l c u l a t i o n s wou ld have to a c coun t f o r the f a c t t h a t the l i q u i d l i n i n g the a i rways i s he t e rogeneous and f o r m e t a b o l i s m o f - 6 -the gas i n the b l o o d . S o l u b i l i t y o f the gas o r vapour i n the a i rway f l u i d i s p r o b a b l y the key f a c t o r d e t e r m i n i n g the s i t e o f a b s o r p t i o n . S u l p h u r d i o x i d e i s h i g h l y s o l u b l e and i s a lmos t c o m p l e t e l y abso rbed i n the nasopharynx (4 ,5 ) whereas ozone i s more i n s o l u b l e and thus p e n e t r a t e s t o the a l v e o l i where f r a c t i o n a l up take i s about 80% i n dogs ( 6 ) . C h r o n i c ozone exposu re has been shown t o e l i c i t a f i b r o b l a s t i c r e s p o n s e i n the t e r m i n a l b r o n c h i o l a r and a l v e o l a r d u c t r e g i o n s ( 7 ) . A c e t o n e and c h l o r i n e a re o f moderate s o l u b i l i t y , thus a re a b s o r b e d p a r t i a l l y by t he nose and p a r t i a l l y by the deepe r a i rways and a l v e o l i ( 1 , 8 ) . The t ime a v a i l a b l e f o r c o n t a c t i s d e t e r m i n e d by f l o w r a t e and b r e a t h i n g p a t t e r n ( e . g . b r e a t h - h o l d i n g ) . I n c r e a s e d d u r a t i o n o f c o n t a c t o n l y i n c r e a s e s a b s o r p t i o n f o r l e s s s o l u b l e gases and o n l y up t o the p o i n t a t wh i ch e q u i l i b r i u m i s r e a c h e d between the p a r t i a l p r e s s u r e s i n the gas and f l u i d l i n i n g ( 8 ) . I n c r e a s e d f l o w r a t e s , w h i l e d e c r e a s i n g c o n t a c t t i m e , a c t u a l l y s e r v e t o i n c r e a s e the e f f i c i e n c y o f a b s o r p t i o n o f s o l u b l e v apou r s by the n a s a l pa s sages ( 9 ,10 ) a l t h o u g h the f r a c t i o n wh i ch p e n e t r a t e s p a s t the nose a l s o t ends t o i n c r e a s e . T h i s l a t t e r e f f e c t was d e m o n s t r a t e d i n dogs by F r a n k and h i s c o l l e a g u e s ( 1 0 ) , who f o u n d the p r o p o r t i o n o f SO^ p e n e t r a t i n g beyond the nose i n c r e a s e d f rom 0 . 1 % t o 3 .2% w i t h a 10 f o l d i n c r e a s e i n f l o w r a t e . In the same e x p e r i m e n t , bu t w i t h mouth b r e a t h i n g , t he p e n e t r a t i o n beyond the nose i n c r e a s e d f rom 0 . 4 % t o 66%. A s i m i l a r e f f e c t i s p o s s i b l e a t s i t e s o f a i rway o b s t r u c t i o n . An - 7 -i n c r e a s e i n f l o w r a t e wou ld t end t o i n c r e a s e the p e n e t r a t i o n beyond the o b s t r u c t i o n ( 1 1 ) . An i n c r e a s e i n f r a c t i o n a l p e n e t r a t i o n o f SO^ o r o t h e r s o l u b l e v apou r s beyond the nose may a l s o r e s u l t f rom a d s o r p t i o n o f t he gas on to i n h a l e d p a r t i c u l a t e (12) o r as a r e s u l t o f s a t u r a t i o n o f t he n a s a l mucosa i f exposu re i s p r o l o n g e d ( 5 ) . The c o n c e n t r a t i o n o f the gas o r vapour i n the i n s p i r e d a i r has a v a r i a b l e e f f e c t on f r a c t i o n a l p e n e t r a t i o n . S 0 2 f r a c t i o n a l up take by the n o s e , b e i n g a lmos t c o m p l e t e , i s l i t t l e a f f e c t e d by c o n c e n t r a t i o n ( 4 ,5 ) whereas ozone f r a c t i o n a l p e n e t r a t i o n beyond the nose i s i n c r e a s e d w i t h i n c r e a s i n g c o n c e n t r a t i o n ( 6 ) . F i n a l l y , i n v i v o a l t e r a t i o n s i n the s i t e o f a b s o r p t i o n may o c c u r as a r e s u l t o f d e s o r p t i o n f rom mucosa l s u r f a c e s and subsequen t f u r t h e r i n h a l a t i o n deep i n t o the l u n g o r e x c r e t i o n d u r i n g e x p i r a t i o n . S p e i z e r and F r a n k (4) f o u n d t h a t a p p r o x i m a t e l y 15% o f a b s o r b e d SO^ may be e x c r e t e d i n t h i s manner . Deeper p e n e t r a t i o n o f d e s o r b e d gas d u r i n g the nex t i n s p i r a t i o n c o u l d r e s u l t i n c o n t i n u e d impa i rment o r damage t o t i s s u e a f t e r exposu re has s t o p p e d . 2. D e p o s i t i o n o f a e r o s o l s P h y s i c a l f a c t o r s wh i ch i n f l u e n c e d e p o s i t i o n o f a e r o s o l s ( d u s t s and m i s t s ) i n the l u n g have been s t u d i e d much more c o m p l e t e l y t han t h o s e r e l a t i n g t o t o x i c g a s e s . These i n c l u d e those wh i ch a r e p r o p e r t i e s o f the a e r o s o l i t s e l f ( s i z e , d e n s i t y , shape , c h a r g e , and - 8 -h y g r o s c o p i c i t y ) and t h o s e r e l a t e d t o the p e r s o n i n h a l i n g ( b r e a t h i n g p a t t e r n and a i rway g e o m e t r y ) . As much o f the work quo t ed i n the f o l l o w i n g s e c t i o n was c a r r i e d ou t u s i n g s o l i d a e r o s o l s ( i e : d u s t s ) , the word p a r t i c l e s i s g e n e r a l l y u s e d ; however , the same g e n e r a l p r i n c i p l e s a p p l y t o l i q u i d a e r o s o l s ( i e : m i s t s ) . The p h y s i c a l mechanisms by wh i ch d e p o s i t i o n can o c c u r have been w e l l d e s c r i b e d by many a u t h o r s ( 1 2 , 1 3 , 1 4 ) and i n c l u d e i m p a c t i o n , s e d i m e n t a t i o n , d i f f u s i o n , and i n t e r c e p t i o n . Impac t i on o c c u r s i n the n a s a l passages and a t a i rway b i f u r c a t i o n s o r any o t h e r o b s t r u c t i o n where the a i r s t r e a m changes d i r e c t i o n and the i n e r t i a l momentum o f the p a r t i c l e ( d e t e r m i n e d by i t s speed and d e n s i t y ) c a r r i e s i t i n t o t he a i rway w a l l . The a n g l e o f change o f d i r e c t i o n and the v e l o c i t y o f a i r f l o w a re s i g n i f i c a n t i n d e t e r m i n i n g the amount o f d e p o s i t i o n t h a t w i l l o c c u r by t h i s mechan ism. G r a v i t a t i o n a l s e t t l i n g , o r s e d i m e n t a t i o n , i s a l s o dependent on the s i z e and d e n s i t y o f the p a r t i c l e s wh i ch d e t e r m i n e i t s s e t t l i n g v e l o c i t y . Such d e p o s i t i o n i s m o d i f i e d by t he speed a t wh i ch a i r i s f l o w i n g though the a i rway (wh ich w i l l t e n d t o c o u n t e r a c t s e t t l i n g ) and the d i a m e t e r o f the a i r w a y . P a r t i c l e s may a l s o d e p o s i t as a r e s u l t o f d i f f u s i o n o r movement due t o bombardment w i t h gas m o l e c u l e s . T h i s i s p a r t i c u l a r l y i m p o r t a n t f o r p a r t i c l e s < 0 . 5 u as a t t h i s s i z e , the r o o t mean squa re d i s p l a c e m e n t due t o d i f f u s i o n e q u a l s the s e t t l i n g v e l o c i t y ( 1 4 ) . P a r t i c l e s wh i ch a re h i g h l y i r r e g u l a r i n shape ( such as a s b e s t o s f i b r e s ) may d e p o s i t i n a i rways by ano the r mechanism no t s i g n i f i c a n t f o r r o u g h l y s p h e r i c a l p a r t i c l e s , name l y , i n t e r c e p t i o n . T h i s mechanism comes i n t o p l a y when - 9 -the p a r t i c l e s i z e i s s i g n i f i c a n t l y l a r g e i n r e l a t i o n to the a i rway s i z e . N o r m a l l y t h i s does no t o c c u r as l a r g e p a r t i c l e s d e p o s i t by i m p a c t i o n o r s e d i m e n t a t i o n b e f o r e r e a c h i n g v e r y s m a l l a i r w a y s ; however , f i b r e s may have a low enough d e n s i t y t o rema in i n t he a i r s t r e a m l o n g e r u n t i l a i rway s i z e becomes i m p o r t a n t i n r e l a t i o n t o f i b r e s i z e . L o n g , s t r a i g h t f i b r e s a re though t t o d e p o s i t by t h i s mechanism t o a g r e a t e r e x t e n t than i r r e g u l a r , c u r l e d ones as a r e s u l t o f t r a v e l l i n g p a r a l l e l t o the a i r s t r e a m and f l i p p i n g end o v e r end i n a p e r i o d i c f a s h i o n ( 1 5 ) . F i n a l l y , d e p o s i t i o n may o c c u r as a r e s u l t o f e l e c t r i c a l f o r c e s between the a i rway w a l l and the p a r t i c l e s . T h e o r e t i c a l l y , a c h a r g e d p a r t i c l e w i l l i nduce an o p p o s i t e \" image c h a r g e \" i n the a i rway w a l l and thus be a t t r a c t e d t o i t . In a d d i t i o n , i f an a e r o s o l c o n s i s t s o f s i m i l a r l y c h a r g e d p a r t i c l e s , r e p u l s i v e f o r c e s w i l l d r i v e t hese a p a r t and thus enhance d e p o s i t i o n . In p r a c t i c e , however , t h e s e e f f e c t s appear t o be i n s i g n i f i c a n t as e x p e r i m e n t a l r e s u l t s i n d i c a t e l i t t l e e f f e c t on d e p o s i t i o n o f p a r t i c l e s when c h a r g e s a re e q u i l i b r a t e d ( 1 6 ) . P a r t i c l e s wh i ch a re s o l u b l e and p r e s e n t i n an env i r onmen t w i t h a r e l a t i v e h u m i d i t y above a c r i t i c a l l e v e l w i l l t ake on wa te r and i n c r e a s e i n s i z e . T h i s can o c c u r i n the o u t d o o r env i ronment and w i t h i n the r e s p i r a t o r y t r a c t . However the a b s o r p t i o n o f wa te r w i l l l ower the d e n s i t y o f the p a r t i c l e , p a r t i a l l y c o u n t e r a c t i n g the e f f e c t o f i n c r e a s e d s i z e . Hounam and Morgan (14) r e p o r t t h a t growth i n s i z e due t o such h y g r o s c o p i c i t y w i l l be s i g n i f i c a n t f o r t o b a c c o smoke bu t no t f o r p e t r o l e u m exhaus t p a r t i c u l a t e , wh i ch a re l o n g - c h a i n a g g r e g a t e s - 10 -and w i l l condense i n humid c o n d i t i o n s t o f o rm more rounded p a r t i c l e s . These mechanisms by wh i ch a e r o s o l d e p o s i t i o n may o c c u r a re d e p e n d e n t , as i n d i c a t e d , on a w ide v a r i e t y o f p h y s i c a l and c h e m i c a l c h a r a c t e r i s t i c s o f the a e r o s o l . However , t he most s i g n i f i c a n t f e a t u r e s o f any a e r o s o l wh i ch i n f l u e n c e d e p o s i t i o n can be d e s c r i b e d by d e f i n i n g the f r e q u e n c y d i s t r i b u t i o n o f the ae rodynamic d i a m e t e r s o f the p a r t i c l e s ( 1 3 ) . The aerodynamic d i a m e t e r o f a p a r t i c l e i s t he d i a m e t e r o f a u n i t d e n s i t y sphe re w i t h e q u a l s e t t l i n g v e l o c i t y as the p a r t i c l e . Any a e r o s o l e n c o u n t e r e d i n the env i ronment w i l l c o n t a i n a d i s t r i b u t i o n o f p a r t i c l e s i z e s , and many o f t hese f i t a \" l o g - n o r m a l \" d i s t r i b u t i o n ( 1 4 ) . D e t e r m i n a t i o n o f the median s i z e ( e i t h e r mass o r coun t median) p l u s the s t a n d a r d d e v i a t i o n d e f i n e s the a e r o s o l . When the p a r t i c l e s a re r a d i o a c t i v e o r t agged w i t h a r a d i o a c t i v e t r a c e r the t e rm a c t i v i t y median ae rodynamic d i a m e t e r i s u sed and t h i s pa ramete r i s e q u a l t o the mass median aerodynamic d i a m e t e r (MMAD) o n l y i f the r a d i o a c t i v i t y i s d i s t r i b u t e d e v e n l y t h r o u g h o u t the p a r t i c l e . The ICRP Task. Group on Lung Dynamics r e v i ewed s t u d i e s on a e r o s o l d e p o s i t i o n and f o r m u l a t e d a d e p o s i t i o n model r e l a t i n g d e p o s i t i o n t o mass median aerodynamic d i a m e t e r ( 1 2 ) . They f o u n d t h a t d e p o s i t i o n i n the v a r i o u s l u n g compartments was b e s t r e l a t e d t o t h i s a e r o s o l pa ramete r and showed s u r p r i s i n g l y l i t t l e v a r i a t i o n even w i t h a e r o s o l s w i t h a wide range o f p a r t i c l e s i z e s (o r a l a r g e s t a n d a r d d e v i a t i o n ) . They c a l c u l a t e d d e p o s i t i o n i n t he n a s o p h a r y n g e a l r e g i o n ( e x t e n d i n g t o the l a r y n x ) , t r a c h e o - b r o n c h i a l r e g i o n ( o r c i l i a t e d a i rways i n c l u d i n g t e r m i n a l b r o n c h i o l e s ) , and pu lmonary r e g i o n - 11 -( i n c l u d i n g r e s p i r a t o r y b r o n c h i o l e s , a l v e o l a r d u c t s and a l v e o l i ) , f o r t h r e e d i f f e r e n t t i d a l vo lumes r e s p r e s e n t i n g m i l d t o h i g h a c t i v i t y s t a t e s and a r e s p i r a t o r y f r e q u e n c y o f IS c y c l e s per m i n u t e . T o t a l r e s p i r a t o r y t r a c t d e p o s i t i o n i n nose b r e a t h i n g s u b j e c t s was c a l c u l a t e d t o be a p p r o x i m a t e l y 100% f o r p a r t i c l e s > 5 u , d e c r e a s i n g t o a minimum o f about 20% f o r 0.5 u p a r t i c l e s and t h e n i n c r e a s i n g a g a i n f o r even s m a l l e r p a r t i c l e s due to d i f f u s i o n . More r e c e n t i n v e s t i g a t i o n s ( 1 4 , 1 7 , 1 8 ) have been i n c l o s e agreement w i t h the T a s k Group f i n d i n g s w i t h the e x c e p t i o n t h a t t o t a l d e p o s i t i o n o f p a r t i c l e s i n the range 0.2 - l u has been f o u n d t o be o n l y about 10% and r e l a t i v e l y c o n s t a n t t h r o u g h o u t t h i s range ( 1 4 ) . The nasopharynx a c t s as a v e r y e f f e c t i v e f i l t e r f o r most l a r g e p a r t i c l e s w i t h i m p a c t i o n b e i n g the major d e p o s i t i o n mechanism i n t h i s r e g i o n . T h u s , f l o w r a t e and d i r e c t i o n a l changes a re the most s i g n i f i c a n t c o n t r i b u t o r s t o enhanced d e p o s i t i o n . The ICRP T a s k Group c a l c u l a t e d t h a t f o r a e r o s o l s > 5 u MMAD n a s o p h a r y n g e a l d e p o s i t i o n wou ld be 70% o r g r e a t e r . More r e c e n t l y , Yu (17) u s i n g a t rumpet l u n g mode l has d e t e r m i n e d v i r t u a l l y i d e n t i c a l d e p o s i t i o n i n t h i s r e g i o n . N a s o p h a r y n g e a l d e p o s i t i o n f a l l s o f f r a p i d l y f o r s m a l l e r s i z e d a e r o s o l s t o a lmos t z e r o f o r 0.1 t o 1 ji p a r t i c l e s . However d e p o s i t i o n by d i f f u s i o n becomes s i g n i f i c a n t f o r e x t r e m e l y s m a l l p a r t i c l e s and m o l e c u l e s . S w i f t (19) r e p o r t s a t o t a l d e p o s i t i o n o f 35% f o r p a r t i c l e s 0 . 0 2 - 0 . 0 4 u o f wh i ch 20-25% was n a s o p h a r y n g e a l , and George and B r e s l i n (20) f o u n d 60% d e p o s i t i o n i n the nasopharynx f o r radon d a u g h t e r s wh i ch were i n i o n i c f o r m . - 12 -P a r t i c l e deposition i n the nasopharynx does not appear to be influenced by the hygroscopicity of the p a r t i c l e s perhaps because t r a n s i t time i s too short (12). Nasal hairs have been suggested as being important f o r deposition and clearance (as mucociliary clearance mechanisms are not active in the region containing nasal hairs) (19) although no d i r e c t measurements have been made of t h e i r c o n t r i b u t i o n . The i n d i v i d u a l v a r i a t i o n found between subjects f o r i n s p i r a t o r y e f f i c i e n c y of nasal deposition has been found to r e l a t e well to the pressure d i f f e r e n c e across the nose and nasopharynx f o r flow rates up 3 to 400 cm /sec (11). The e f f i c i e n c y of the nose in preventing penetration of a great proportion of inhaled p a r t i c l e s leads on occasion to disease i t s e l f . Nasal cancer among wood f u r n i t u r e makers and boot and shoemakers (21) and perforation of the nasal septum in workers exposed to chromate (22) have been a t t r i b u t e d to deposition of aerosol p a r t i c l e s on the nasal septum. P a r t i c l e s are deposited much les s r e a d i l y in the tracheobronchial region of the re s p i r a t o r y t r a c t . The ICRP Task Group (12) found a r e l a t i v e l y constant deposition of about 8% of in s p i r e d dust f o r p a r t i c l e s )> 0.05 u which occurs mainly as r e s u l t of impaction at b i f u r c a t i o n s as well as some sedimentation due to the small airway diameters. Deposition f o r smaller p a r t i c l e s increases as t o t a l p a r t i c l e deposition increases. Somewhat higher r e s u l t s f o r 3 small p a r t i c l e s (< .Ol/i) deposition i n t h i s region at 750 cm t i d a l volume have been reported more recently (17). Enhanced - 13 -t r a c h e o b r o n c h i a l d e p o s i t i o n may o c c u r as r e s u l t o f h y g r o s c o p i c p a r t i c l e s i n c r e a s i n g i n s i z e as t hey t r a v e l t h rough the a i r w a y s . C i g a r e t t e smoke p a r t i c l e s range f rom 0.2 t o 1.5u d i a m e t e r (22) and thus wou ld no t n o r m a l l y d e p o s i t on a i rway w a l l s t o any l a r g e e x t e n t . However , up take o f wa te r f rom the a i rways (which a re a lmos t c o m p l e t e l y s a t u r a t e d ) wou ld r e s u l t i n c o n s i d e r a b l e i n c r e a s e i n s i z e and consequen t d e p o s i t i o n on b r o n c h i a l w a l l s . Most m a t e r i a l wh i ch p e n e t r a t e s the l a r y n x i s e i t h e r d e p o s i t e d i n the pu lmonary compartment o r e x h a l e d . Pu lmonary d e p o s i t i o n i n c r e a s e s t o about 30% f o r a e r o s o l s w i t h MMAD f rom 0 .5u t o 5u w i t h a maximum d e p o s i t i o n o c c u r r i n g f o r p a r t i c l e s o f 2-3 u ( 1 2 , 1 3 ) . A s h a r p i n c r e a s e i n d e p o s i t i o n o c c u r s f o r v e r y s m a l l p a r t i c l e s (<. O . l u ) f o r wh i ch d i f f u s i o n becomes i m p o r t a n t as a d e p o s i t i o n mechan ism. The s i g n i f i c a n t mechanisms r e s p o n s i b l e f o r a l v e o l a r d e p o s i t i o n a r e s e d i m e n t a t i o n and d i f f u s i o n but i t has been p r o p o s e d (23) t h a t m i x i n g o f t i d a l and r e s i d u a l a i r i n the a i rways i s the r a t e - l i m i t i n g p r o c e s s . Pu lmonary d e p o s i t i o n c a l c u l a t e d by Yu (17 ,18 ) i s c o n s i d e r a b l y l ower than the T a s k Group c a l c u l a t i o n s w i t h a minimum o f about 10% 3 d e p o s i t i o n f o r 0 .3u p a r t i c l e s a t 750 cm t i d a l vo lume . W i t h i n the t r a c h e o - b r o n c h i a l and pu lmonary compartments t h e r e i s c o n s i d e r a b l e h e t e r o g e n e i t y o f a e r o s o l d e p o s i t i o n t h a t i s no t r e f l e c t e d by c a l c u l a t i o n s o r e x p e r i m e n t a t i o n on d e p o s i t i o n i n t he compartments as a w h o l e . A t a i rway b i f u r c a t i o n s , ho t s p o t s have been shown t o d e v e l o p w i t h enhanced d e p o s i t i o n s e v e r a l t imes g r e a t e r t han the ave rage ( 2 4 ) . An apex t o base g r a d i e n t has a l s o been r e p o r t e d - 14 -w i t h i n c r e a s e d d e p o s i t i o n i n a p i c a l r e g i o n s i n the dog (25) and the r a t ( 2 6 ) , r e g a r d l e s s o f body o r i e n t a t i o n . On the m i c r o s c o p i c l e v e l , d e p o s i t i o n may a l s o be he t e rogeneous w i t h i n the a c i n u s . B rody and h i s c o l l e a g u e s (27 ,28 ) have shown a s b e s t o s f i b r e d e p o s i t i o n i n r a t s t h r o u g h o u t the t r a c h e o b r o n c h i a l t r e e bu t p a r t i c u l a r l y a t b i f u r c a t i o n s . They a l s o d e t e r m i n e d t h a t f i b r e s wh i ch p e n e t r a t e beyond the c o n d u c t i n g a i rways d e s p o i t m a i n l y on b i f u r c a t i o n s o f the p r o x i m a l a l v e o l a r d u c t s . I t i s a p p a r e n t f rom the f o r e g o i n g t h a t a e r o s o l s i z e c h a r a c t e r i s t i c s a re key f a c t o r s i n f l u e n c i n g the amount and l o c a t i o n o f d e p o s i t i o n w i t h i n the r e s p i r a t o r y t r a c t . However, a f e a t u r e common t o most e x p e r i m e n t a l i n v e s t i g a t i o n s o f d e p o s i t i o n i s the wide deg ree o f v a r i a t i o n between i n d i v i d u a l r e s u l t s and even between s e p a r a t e s t u d i e s on the same p e r s o n . A l a r g e amount o f t h i s v a r i a t i o n has been shown t o be r e l a t e d t o b r e a t h i n g p a t t e r n . I n s p i r a t i o n t h r o u g h the mouth r e s u l t s i n i n c r e a s e d p e n e t r a t i o n o f p a r t i c l e s i n t o the t r a c h e o b r o n c h i a l compartment . F o o r d and c o l l e a g u e s (29) s t u d i e d d e p o s i t i o n o f p a r t i c l e s f rom 2.5 t o 7.5ji i n mouth b r e a t h i n g s u b j e c t s and f o u n d t r a c h e o b r o n c h i a l d e p o s i t i o n f r o m 10 t o 39% ove r t h i s r a n g e . Mouth b r e a t h i n g t y p i c a l l y o c c u r s d u r i n g a h i g h a c t i v i t y s t a t e and i s u s u a l l y accompan ied by an i n c r e a s e i n t i d a l vo l ume . D a v i e s has compared a s e d e n t a r y b r e a t h i n g p a t t e r n ( i n n o s e , ou t mouth , w i t h a m inu te volume o f 7.5 1.) t o an a c t i v e b r e a t h i n g p a t t e r n ( i n and ou t mouth , m inu te volume 50 1.) f o r p a r t i c l e s f rom 0 .5 t o 5u and c a l c u l a t e s a d o u b l i n g o f d e p o s i t i o n beyond the l a r y n x f o r 2fi - 15 -p a r t i c l e s and t r i p l i n g f o r 5u p a r t i c l e s bu t l i t t l e change f o r 0 .5 and 1.0 u p a r t i c l e s . The p a t t e r n o f d e p o s i t i o n i n the t r a c h e o b r o n c h i a l compared t o pu lmonary compartment r ema ined about the same ( r e p o r t e d as p e r s o n a l commun i ca t i on by Park.es ( 2 2 ) ) . An i n c r e a s e i n f l o w v e l o c i t y r e s u l t s i n t u r b u l e n t f l o w a t deepe r l e v e l s o f the r e s p i r a t o r y t r a c t and thus g r e a t e r m i x i n g o f the a e r o s o l w i t h r e s i d u a l gas ( 1 3 ) . T h i s has the p o t e n t i a l e f f e c t o f i n c r e a s i n g i n e r t i a l i m p a c t i o n d u r i n g r a p i d b r e a t h i n g . T h i s c an be o f f s e t by o t h e r changes i n the b r e a t h i n g p a t t e r n . V a l b e r g and c o l l e a g u e s (25) s t u d i e d s l o w , d e e p ; s l o w , s h a l l o w ; and r a p i d , s h a l l o w b r e a t h i n g i n dogs and f o u n d t h a t t o t a l d e p o s i t i o n d e c r e a s e d w i t h i n c r e a s i n g f r e q u e n c y o f b r e a t h i n g and d e c r e a s e d t i d a l vo lume . T h i s i s i n agreement w i t h the p r e d i c t i o n s o f Yu and T a u l b e e (18) who c a l c u l a t e d s i m i l a r r e s u l t s w i t h v a r y i n g t i d a l volume and f r e q u e n c y . B r e a t h - h o l d i n g has a l s o been s t u d i e d and shown t o a f f e c t d e p o s i t i o n i n a major f a s h i o n . G o l d b e r g and Smi th (30) r e p o r t e d t h a t t he f r a c t i o n o f a e r o s o l d e p o s i t e d was e x p o n e n t i a l l y r e l a t e d t o b r e a t h h o l d i n g t ime and t h a t t h i s was due t o i n c r e a s e s i n b o t h d i f f u s i o n a l and g r a v i t a t i o n a l d e p o s i t i o n . S i m i l a r r e s u l t s were a l s o f ound by Palmes and a s s o c i a t e s ( 3 1 ) . The s i g n i f i c a n c e o f a l t e r e d d e p o s i t i o n due t o b r e a t h i n g p a t t e r n i s emphas i zed by a r e c e n t s t udy by H igenbo t t am and c o l l e a g u e s (32) who s t u d i e d c i g a r e t t e smokers w i t h v a r y i n g smoke i n h a l a t i o n p a t t e r n s . They f ound c o n s i s t e n t a i rway n a r r o w i n g when the s u b j e c t s drew the smoke d i r e c t l y i n t o t h e i r l u n g s t h rough the mouth , but no - 16 -c o n s i s t e n t r e s p o n s e when the i n h a l a t i o n p a t t e r n was \" n o r m a l \" , c o n s i s t i n g o f an i n i t i a l d raw ing o f smoke i n t o the mouth , a pause w i t h some e x p i r a t i o n , and then i n h a l a t i o n t h r o u g h nose and mouth . F i n a l l y , d e p o s i t i o n may be a f f e c t e d by v a r i a t i o n s i n a i rway geomet r y , whether t h e s e a re i n h e r e n t o r r e l a t e d t o the p r e s e n c e o f d i s e a s e . B r o n c h i a l c r o s s - s e c t i o n a l a r ea s have been shown t o v a r y c o n s i d e r a b l y among i n d i v i d u a l s i n r e l a t i o n t o s t a t u r e ( 3 3 ) . C a l c u l a t i o n o f the magn i tude o f a d e p o s i t i o n pa ramete r r e f l e c t i n g r e s p i r a t o r y a i r s p a c e d i m e n s i o n s by Palmes and L ippmann (34) i n d i c a t e a p o t e n t i a l f o r a d o u b l i n g o f t r a c h e o b r o n c h i a l d e p o s i t i o n r e l a t e d s o l e l y t o t h i s f a c t o r . A i rway d i s e a s e a l s o i n f l u e n c e s d e p o s i t i o n w i t h , i n most c a s e s , p r e f e r e n t i a l a i rway o v e r pu lmonary d e p o s i t i o n . C i g a r e t t e smokers t e n d t o have more p r o x i m a l d e p o s i t i o n ( 35 , 36) as do p a t i e n t s w i t h asthma and c h r o n i c b r o n c h i t i s ( 3 7 ) . These f i n d i n g s may be the r e s u l t o f s e v e r a l i n t e r a c t i n g mechan isms . A i rway o b s t r u c t i o n i n c r e a s e s t u r b u l e n c e and t h e r e f o r e promotes m i x i n g and i n c r e a s e d i n e r t i a l i m p a c t i o n . B r o n c h o c o n s t r i c t i o n may a c t s i m i l a r l y and b o t h may a l s o d i v e r t f l o w t o o t h e r a r eas r e s u l t i n g i n g r e a t e r h e t e r o g e n e i t y o f d e p o s i t i o n . E x c e s s i v e s e c r e t i o n s have a l s o been i m p l i c a t e d i n i n c r e a s i n g t u r b u l e n c e due to wave m o t i o n w i t h l i t t l e o r no change i n a i rway r e s i s t a n c e ( 3 8 ) . The h e t e r o g e n e i t y and i n c r e a s e d a i rway d e p o s i t i o n r e s u l t i n g f rom a i rway d i s e a s e may p l a y a r o l e i n t he p a t h o g e n e s i s o f b r o n c h o g e n i c c a r c i n o m a . - 17 -REFERENCES - CHAPTER I I 1. H inds WC: The l u n g and the e n v i r o n m e n t . Sem Resp Med 1980 ; 1:197-210 2. West JB : R e s p i r a t o r y P h y s i o l o g y B a l t i m o r e : W i l l i a m s and W i l k i n s , 1979 3. S l o n i m NB, H a m i l t o n LH : R e s p i r a t o r y P h y s i o l o g y S t . L o u i s : C V . Mosby , 1981 4 . S p e i z e r F E , F r a n k NR: The uptake and r e l e a s e o f SO^ by t he human n o s e . A r c h E n v i r o n H e a l t h 1966 ; 12 :725-728 5. Ande r sen I, Gunner GR, J ensen PL , P r o c t o r DL : Human r e s p o n s e t o c o n t r o l l e d l e v e l s o f s u l f u r d i o x i d e . A r c h E n v i r o n H e a l t h 1974 ; 28 :31-39 6. Yokoyama E, F r a n k R: R e s p i r a t o r y up take o f ozone i n d o g s . A r c h E n v i r o n H e a l t h 1972 ; 25 :132-138 7. C r o s s C E , H e s t e r b e r g TW, R e i s e r KM, L a s t JA : Ozone t o x i c i t y as a mode l o f l u n g f i b r o s i s . C h e s t 1981 ; 80(1 S u p p l ) : 5 2 - 5 4 8. Morgan MS, F r a n k R: Uptake o f p o l l u t a n t gases by the r e s p i r a t o r y s y s t e m . I n : B r a i n JD , P r o c t o r DF, R e i d LM, e d s , R e s p i r a t o r y De fense Mechanisms New Y o r k : M a r c e l Dekke r , 1977:157-189 9. Aha ronson E F , Menkes H, G u r t n e r G , S w i f t DL , P r o c t o r DF : E f f e c t o f r e s p i r a t o r y a i r f l o w r a t e on remova l o f s o l u b l e v apou r s by the n o s e . J A p p l P h y s i o l 1974 ; 37 :654-657 35 1 0 . F r a n k NR, Yode r RE , B r a i n JD , Yokoyama E: S 0 2 ( S - l a b e l e d ) a b s o r p t i o n by the nose and mouth under c o n d i t i o n s o f v a r y i n g c o n c e n t r a t i o n and f l o w . A r c h E n v i r o n H e a l t h 1969 ; 18 :315-322 - 18 -1 1 . Heyder J , R u d o l f G: D e p o s i t i o n o f a e r o s o l p a r t i c l e s i n t he human n o s e . I n : Wa l ton WH, e d , I n h a l e d P a r t i c l e s IV O x f o r d : Pergamon P r e s s , 1977:107-125 12 . T a s k Group on Lung Dynamics . D e p o s i t i o n and r e t e n t i o n mode ls f o r i n t e r n a l d o s i m e t r y o f the human r e s p i r a t o r y t r a c t . H e a l t h P h y s i c s 1966 , 12 :173-207 1 3 . B r a i n JD , V a l b e r g PA: D e p o s i t i o n o f a e r o s o l i n the r e s p i r a t o r y t r a c t . Am Rev R e p i r D i s 1979 ; 120:1325-1373 14 . Hounman RF , Morgan A : P a r t i c l e d e p o s i t i o n . I n : B r a i n JD , P r o c t o r DF , R e i d LM, e d s , R e s p i r a t o r y De fense Mechan i sms , New Y o r k : M a r c e l Dekke r , 1977:125-156 1 5 . H a r r i s J r . RL , T i m b r e l l V : The i n f l u e n c e o f f i b r e shape i n l u n g d e p o s i t i o n - m a t h e m a t i c a l e s t i m a t e s . I n : Wa l ton WH, e d , I n h a l e d P a r t i c l e s IV O x f o r d : Pergamon P r e s s , 1977:75-88 16 . F r y FA : Charge d i s t r i b u t i o n on p o l y s t y r e n e a e r o s o l s and d e p o s i t i o n i n the human n o s e . J A e r o s o l S c i 1970 ; 1:135-146 1 7 . Yu CP : E x a c t a n a l y s i s o f a e r o s o l d e p o s i t i o n d u r i n g s t eady s t a t e b r e a t h i n g . Powder T e c h n o l o g y 1978 ; 21 :55-62 1 8 . Yu CP , T a u l b e e DB: A t h e o r y o f p r e d i c t i n g r e p i r t o r y t r a c t d e p o s i t i o n o f i n h a l e d p a r t i c l e s i n man. I n : Wa l ton WH, e d , I n h a l e d P a r t i c l e s IV O x f o r d : Pergamon P r e s s , 1977:35-46 19 . S w i f t DL : A e r o s o l d e p o s i t i o n and c l e a r a n c e i n the human upper a i r w a y s . Ann Biomed E n g i n 1981 ; 9 :593-604 20 . George A , B r e s l i n A J : D e p o s i t i o n o f r adon d a u g h t e r s i n humans exposed t o u r an ium mine a tmosphe re s . H e a l t h P h y s i c s 1969 ; 17 :115-124 - 19 -2 1 . Acheson E C , C o w d e l l RH, Rang E: Adenoca r c i noma o f the n a s a l c a v i t y and s i n u s e s i n E n g l a n d and W a l e s . B r i t J Ind Med 1972 , 29 :21-30 22 . Park.es WR: O c c u p a t i o n a l Lung D i s o r d e r s . B u t t e r w o r t h s , L o n d o n , 1982 2 3 . D a v i e s CN: B r e a t h i n g o f h a l f - m i c r o n a e r o s o l s . I I . I n t e r p r e t a t i o n o f e x p e r i m e n t a l r e s u l t s . J A p p l P h y s i o l 1972 ; 32 :601-611 24 . S c h l e s i n g e r RB, L ippmann M: P a r t i c l e d e p o s i t i o n i n c a s t s o f the human upper t r a c h e o b r o n c h i a l t r e e . Am Ind Hyg A s s o c J 1972 , 33 :237-51 2 5 . V a l b e r g PA, B r a i n JD , Sneddon SL , LeMot t SR: B r e a t h i n g p a t t e r n s i n f l u e n c e a e r o s o l d e p o s i t i o n s i t e s i n e x c i s e d dog l u n g s . J A p p l P h y s i o l 1982 ; 53 :824-837 26 . Sneddon SL , B r a i n JD: P e r s i s t e n t apex t o base g r a d i e n t s o f a e r o s o l d e p o s i t i o n i n r a t s . R e s p i r P h y s i o l 1981 ; 46 :113-124 2 7 . B rody AR, H i l l L H , A d k i n s J r B, O 'Conno r RW: C h r y s o t i l e a s b e s t o s i n h a l a t i o n i n r a t s : d e p o s i t i o n p a t t e r n and r e a c t i o n o f a l v e o l a r e p i t h e l i u m and pu lmonary mac rophages . Am Rev R e s p i r D i s 1981 ;123 :670-679 28 . B rody AR, H i l l LH : D e p o s i t i o n p a t t e r n and c l e a r a n c e pathways o f i n h a l e d c h r y s o t i l e a s b e s t o s . C h e s t 1981 ; 80(1 s u p p l ) : 64-67 29 . F o o r d N, B l a c k A , Wa lsh M: Pu lmonary d e p o s i t i o n o f i n h a l e d p a r t i c l e s w i t h d i a m e t e r s i n the range 2.5 t o 7.5 urn. I n : Wa l ton WH, e d , I n h a l e d P a r t i c l e s IV O x f o r d : Pergamon P r e s s 1977:137-148 - 20 -3 0 . G o l d b e r g I S , Smi th RB: S e t t l i n g and d i f f u s i o n o f a e r o s o l p a r t i c l e s i n s m a l l a i rways d u r i n g b r e a t h h o l d i n g . Ann Biomed E n g i n 1981 ; 9 :557-575 3 1 . Palmes ED, Wang C , G o l d r i n g RM, A l t s h u l e r B: E f f e c t o f d e p t h o f i n h a l a t i o n on a e r o s o l p e r s i s t e n c e d u r i n g b r e a t h h o l d i n g . J A p p l P h y s i o l 1973 ; 34 :356-360 32 . H igenbo t t am T , F e ye r aband C , C l a r k T JH: C i g a r e t t e smoke i n h a l a t i o n and the a cu t e a i rway r e s p o n s e . Thorax 1980 ; 35 :246-254 3 3 . T h u r l b e c k WM, Ha ines JR: B r o n c h i a l d i m e n s i o n s and s t a t u r e . Am Rev R e s p i r D i s 1975 ; 112:142-145 34 . Palmes ED, L ippmann M: I n f l u e n c e o f r e s p i r a t o r y a i r space d i m e n s i o n s on a e r o s o l d e p o s i t i o n . I n : Wa l ton WH, e d , I n h a l e d P a r t i c l e s IV O x f o r d : Pergamon P r e s s , 1977:127-148 3 5 . S a n c h i s J , D o l o v i c h M, Cha lmers R, Newhouse MT: R e g i o n a l d i s t r i b u t i o n and l u n g c l e a r a n c e mechanisms i n smokers and non-smokers . I n : Wa l ton WH, e d , I n h a l e d P a r t i c l e s I I I O l d Wok ing : Unwin , 1971:183-188 3 6 . D o l o v i c h MB, S a n c h i s J . Rossman C , Newhouse MT: A e r o s o l p e n e t r a n c e : a s e n s i t i v e index o f p e r i p h e r a l a i rways o b s t r u c t i o n . J A p p l P h y s i o l 1976 , 40 :468-471 3 7 . L ippmann M, A l b e r t RE, P e t e r s o n HT: The r e g i o n a l d e p o s i t i o n o f i n h a l e d a e r o s o l s i n man. I n : Wa l ton WH, e d , I n h a l e d P a r t i c l e s I I I O l d Wok ing : Unwin , 1971:105-120 3 8 . Kim CS , Abraham WM, Chapman GA, Sackne r MA: I n fuence o f two-phase g a s - l i q u i d i n t e r a c t i o n t o a e r o s o l d e p o s i t i o n i n t he a i r w a y s . Am Rev R e s p i r D i s 1983 ; 127 :176 - 21 -I I I . Lung C l e a r a n c e Mechanisms The oxygen r e q u i r e m e n t s o f the body must be met by p a s s i v e d i f f u s i o n o f oxygen a c r o s s the b l o o d - a i r b a r r i e r i n the l u n g . T h i s means t h a t the a r e a f o r r e s p i r a t o r y exchange i n the l u n g must be immense i n o r d e r to s u p p l y the b o d y ' s m e t a b o l i c n e e d s . T h i s s u r f a c e a r e a o f a l v e o l a r w a l l has been e s t i m a t e d a t 200 o r more squa re m e t e r s , i n 300-400 m i l l i o n a l v e o l i , w i t h a t h i c k n e s s o f a p p r o x i m a t e l y 0 .5 m i c r o n s ( 1 ) . W i th an i n h a l e d volume o f f rom 10 ,000 t o 20 ,000 1. o f a i r p e r d a y , t h i s v a s t expanse o f d e l i c a t e t i s s u e i s a t o b v i o u s r i s k i f the i n h a l e d a i r c o n t a i n s t o x i n s o r i r r i t a n t s . S e v e r a l d e f e n s i v e s t r u c t u r e s and mechanisms work t o p r e v e n t the passage o f i n j u r i o u s agen ts i n t o the l u n g parenchyma o r t o remove t h o s e t h a t a v o i d t he d e f e n s i v e f i l t e r . These have been r e v i ewed e x t e n s i v e l y r e c e n t l y ( 2 , 3 , 4 , 5 , 6 ) and w i l l o n l y be d i s c u s s e d b r i e f l y h e r e . 1. Upper A i rway De fences The n a s a l a i r passages r e p r e s e n t an e x t r e m e l y i m p o r t a n t f i r s t l i n e o f d e f e n s e a g a i n s t l a r g e p a r t i c l e s and s o l u b l e g a s e s , a c t i n g as bo th a f i l t e r f o r t r a p p i n g p a r t i c l e s and a h i g h l y v a s c u l a r s i n k f o r up take o f wa te r s o l u b l e g a s e s . The e x t r e m e l y v a r i a b l e v a s c u l a r i t y and r i c h s e c r e t o r y sys tem o f the n a s a l a i r passages a l s o p r o v i d e s f o r warming and h u m i d i f i c a t i o n o f i n h a l e d a i r , an e s s e n t i a l e l ement i n the - 22 -ma in tenance o f the e q u i l i b r i u m o f the l ower r e s p i r a t o r y o r g a n . W i th i n c r e a s e d f l o w r a t e s , as e n c o u n t e r e d i n l i g h t p h y s i c a l e x e r t i o n , n a s a l a i r passage d i m e n s i o n s a re i n c r e a s e d s l i g h t l y (7), d e c r e a s i n g r e s i s t a n c e and a l l o w i n g c o n t i n u e d nose b r e a t h i n g . The i n c r e a s e i n f l o w r a t e a l l o w s f o r g r e a t e r i m p a c t i o n o f i n h a l e d p a r t i c l e s i n the a n t e r i o r n a r e s . However w i t h h e a v i e r e x e r c i s e , t he r e s i s t a n c e o f the n a s a l passages becomes t o o l a r g e t o meet the v e n t i l a t o r y demand, and mouth b r e a t h i n g o c c u r s (8). A t t h i s p o i n t , b o t h the f i l t e r i n g and c o n d i t i o n i n g f u n c t i o n s a re b y p a s s e d . T h i s i s an i m p o r t a n t c o n s i d e r a t i o n i n assessment o f o c c u p a t i o n a l e x p o s u r e s i f the work i n v o l v e s heavy p h y s i c a l e x e r t i o n . I t must a l s o be t aken i n t o a c coun t i n assessment o f exposu re t o p o l l u t a n t s wh i ch cause n a s a l c o n g e s t i o n , o r i n assessment o f i n d i v i d u a l r i s k i n p e r s o n s w i t h i n c r e a s e d n a s a l r e s i s t a n c e o r d e c r e a s e d c l e a r a n c e f o r any r e a s o n . C i g a r e t t e smok ing , o f c o u r s e , a l s o c o m p l e t e l y bypasses the n a s a l d e f e n s e s . In s i t u a t i o n s o f c o n t i n u e d bypass o f the n a s a l d e f e n s e mechan i sms , such as i n p a t i e n t s w i t h l o n g - s t a n d i n g t r a c h e o s t o m y , t h e r e i s neve r comp le te compensa t i on f o r t h i s l o s s , w i t h the r e s u l t t h a t t h o s e p a t i e n t s s u f f e r f rom c h r o n i c b r o n c h i t i s , w i t h squamous m e t a p l a s i a o f l a r g e a i rways and i m p a i r e d m u c o c i l i a r y c l e a r a n c e ( 2 ) . D . F . P r o c t o r has p r o p o s e d (2) t h a t p e r s o n s w i t h m ino r impa i rment o f n a s a l c l e a r a n c e and c o n d i t i o n i n g mechanisms may be p u t t i n g an undue burden on the s m a l l e r a i r w a y s , p r e d i s p o s i n g them t o d i s e a s e . He a rgues t h a t the l a r g e c o n d u c t i n g a i rways a re u n s u i t e d t o comp le t e the - 23 -a i r - c o n d i t i o n i n g p r o c e s s but the s m a l l , p e r i p h e r a l a i r w a y s , may w e l l be a b l e t o t a ke up the r ema inde r o f the j o b . However, i n o r d e r t o do t h i s t hey may r e s o r t t o the p r e f e r e n t i a l deve lopment o f g o b l e t c e l l s r a t h e r than c i l i a t e d c e l l s , l e a d i n g , i f p r o l o n g e d , t o i m p a i r e d c i l i a r y c l e a r a n c e , a l t e r e d s u r f a c e t e n s i o n p r o p e r t i e s and u l t i m a t e l y , d y s f u n c t i o n o f t h e s e s m a l l a i r w a y s . P r o c t o r has f u r t h e r shown (9) t h a t n a s a l c l e a r a n c e and r e s i s t a n c e v a r i e s among norma l i n d i v i d u a l s and s u g g e s t s t h a t i n v e s t i g a t i o n o f t hese p r o p e r t i e s may r e v e a l i n d i v i d u a l s a t g r e a t e r r i s k f o r f u t u r e l u n g damage. 2. T r a c h e o - b r o n c h i a l d e f e n s e s a) M u c o - c i l i a r y c l e a r a n c e The t r a c h e a and a i rways w i t h i n the l u n g r e p r e s e n t the s e cond l i n e o f d e f e n s e a g a i n s t p o l l u t a n t s wh i ch e s cape the n a s a l f i l t e r . The key mechanism a t t h i s l e v e l i s the t r a p p i n g and c l e a r a n c e o f p a r t i c l e s by the m u c o - c i l i a r y e s c a l a t o r . The s u c c e s s o f t h i s s ys tem depends on c o n t a c t o f p a r t i c l e s w i t h the a i rway w a l l s ; e f f i c i e n t , c o o r d i n a t e d c i l i a r y movement; and mucus with b i o c h e m i c a l and Theological c h a r a c t e r i s t i c s c o n d u c i v e t o b o t h ent rappment o f p a r t i c l e s and movement by c i l i a r y b e a t i n g . P a r t i c l e s d e p o s i t e d on the mucous l a y e r a r e c a r r i e d ups t r eam as a r e s u l t o f the c i l i a r y b e a t i n g wh i ch p r o p e l s mucus d r o p l e t s toward the p h a r y n x . T h i s \"mucous b l a n k e t \" i s b e l i e v e d t o be a he t e rogeneous and - 24 -v a r i a b l e l i n i n g r a t h e r than a c o n t i n u o u s l a y e r . I t i s made up o f v a r y i n g p r o p o r t i o n s o f mucous and s e rous s e c r e t i o n s f rom s p e c i a l i z e d submucosa l g l a n d s and g o b l e t c e l l s , serum and t i s s u e t r a n s u d a t e s , and i n f l a m m a t o r y i n f i l t r a t e s . In the norma l h e a l t h y p e r s o n the volume o f t h i s f l u i d amounts t o about 10 ml p e r day ( 1 4 ) . Lucas and Doug las (15) i n i t i a l l y p r o p o s e d the c o n c e p t t h a t the a r c h i t e c t u r e o f t h i s f l u i d l a y e r i s t h a t o f a w a t e r y , s e rous o r s o l - p h a s e a d j a c e n t t o t he e p i t h e l i a l c e l l s u r f a c e s and s u r r o u n d i n g the c i l i a and an o v e r l y i n g , mucous o r g e l - p h a s e . I t has s i n c e been p r o p o s e d (16) t h a t the mucous \" b l a n k e t \" , o r g e l - p h a s e , i s d i s c o n t i n u o u s , a t l e a s t i n the more d i s t a l a i r w a y s . C i l i a a r e b e l i e v e d t o bea t i n such a manner t h a t the r a p i d , e f f e c t i v e s t r o k e o c c u r s w i t h the c l a w - l i k e t i p o f the c i l i a e x t e n d i n g j u s t to the g e l phase and p r o p e l l i n g i t f o r w a r d e i t h e r d i r e c t l y by c o n t a c t w i t h the mucus d r o p l e t s o r i n d i r e c t l y by sweeping the mucus a l o n g w i t h the upper p o r t i o n s o f the s o l p h a s e . The s low r e c o v e r y s t r o k e o f the c i l i a t a k e s p l a c e i n the more w a t e r y , p e r i - c i l i a r y s o l - p h a s e . E x t e n s t i v e i n v e s t i g a t i o n has been c a r r i e d out i n r e c e n t y e a r s t o c h a r a c t e r i z e the b i o c h e m i c a l and p h y s i c a l p r o p e r t i e s o f the a i rway l i n i n g f l u i d s , t o d e t e r m i n e how t h e s e p r o p e r t i e s a re i n f l u e n c e d by i n h a l e d s u b s t a n c e s , and t o d e t e r m i n e whether changes i n t he f l u i d l i n i n g c h a r a c t e r i s t i c s l e a d t o o r a re a s s o c i a t e d w i t h a l t e r e d pu lmonary f u n c t i o n o r r e s p i r a t o r y d i s e a s e ( 1 7 , 1 8 , 1 9 ) . A n a l y s i s o f changes i n a i rway s e c r e t i o n s i s g e n e r a l l y c a r r i e d ou t by sputum a n a l y s i s o r by s p e c i a l h i s t o c h e m i c a l s t a i n i n g o f s e c t i o n s c o n t a i n i n g - 25 -a i rway w a l l s . I t must be n o t e d t h a t p r o d u c t i o n o f sputum i m p l i e s d i s e a s e and t h e r e f o r e a n a l y s i s o f sputum does not p r o v i d e \" n o r m a l \" d a t a . C e n t r i f u g a t i o n o f sputum f rom c h r o n i c b r o n c h i t i c s r e s u l t s i n s e p a r a t i o n i n t o s o l and g e l p h a s e s , w i t h the s o l phase c o n t a i n i n g m o s t l y s o l u b l e serum g l y c o p r o t e i n s and the g e l p h a s e , i n s o l u b l e e p i t h e l i a l g l y c o p r o t e i n s ( 3 ) . H i s t o c h e m i c a l s t a i n i n g o f g o b l e t c e l l s and submucosa l g l a n d s w i t h A l c i a n b l u e - p e r i o d i c a c i d S c h i f f s t a i n s e p a r a t e s a c i d and n e u t r a l g l y c o p r o t e i n s r e s p e c t i v e l y . S t a i n i n g a t pH 0 .5 v e r s u s pH 2.5 d i f f e r e n t i a t e s s i a l o - and su lphomuc ins and s i a l i d a s e d i g e s t i o n r e v e a l s s i a l i d a s e r e s i s t a n t s i a l o m u c i n s . These t e c h n i q u e s show t h a t g o b l e t c e l l s c o n t a i n m o s t l y a c i d g l y c o p r o t e i n (bo th s u l p h o and s i a l o m u c i n s ) , mucous c e l l s c o n t a i n f o u r t ypes o f a c i d g l y c o p r o t e i n s , and s e rous c e l l s c o n t a i n s i a l o - and su lphomuc ins b u t w i t h d i f f e r e n t c h a r a c t e r i s t i c s than t h o s e i n mucous c e l l s . Changes i n sputum o r h i s t o c h e m i c a l s t a i n i n g w i t h v a r i o u s d i s e a s e s t a t e s and e x p o s u r e s have been summar ized by L o p e z - V i d r i e r o , Das and R e i d ( 1 7 ) . Sputum f rom c h r o n i c b r o n c h i t i c s compared t o t h a t p r o d u c e d by norma l s u b j e c t s g i v e n PGF^o* t o i nduce e x p e c t o r a t i o n d i f f e r s i n h a v i n g a h i g h e r mannose c o n t e n t s u g g e s t i n g g r e a t e r serum t r a n s u d a t e , i n c r e a s e d l e v e l s o f b o t h e p i t h e l i a l and serum a c i d g l y c o p r o t e i n , and an i n c r e a s e i n s u l p h a t e d g l y c o p r o t e i n p r o d u c t i o n . T h i s l a s t i s a l s o seen i n h i s t o c h e m i c a l s t u d i e s o f a n i m a l s exposed t o c i g a r e t t e smoke o r SO^ ( 2 0 ) . SO^ exposu re o f c a n i n e t r a c h e a l pouch p r e p a r a t i o n s has a l s o been shown t o cause s i g n i f i c a n t changes i n mucus e l a s t i c i t y (by a r e f l e x a c t i o n , as t h e r e was no d i r e c t c o n t a c t - 26 -between the gas and the pouch mucosa) ( 2 1 ) . What e f f e c t t h e s e changes have on the d e f e n s i v e a c t i o n o f the l u n g i s l e s s c l e a r . The i n t e r a c t i o n between c i l i a r y movement and mucus p r o p u l s i o n has been r e p o r t e d t o depend on the r h e o l o g i c a l p r o p e r t i e s o f mucus ( v i s c o s i t y and e l a s t i c i t y ) r a t h e r than the s p e c i f i c b i o c h e m i c a l make-up ( 2 2 , 2 3 ) . However , t he r h e o l o g i c a l p r o p e r t i e s o f mucus i n humans a re b e l i e v e d t o be d e t e r m i n e d by t he a r rangement o f the g l y c o p r o t e i n m o l e c u l e s and the p r e s e n c e o f c r o s s - l i n k a g e s , and v i s c o s i t y has been r e l a t e d t o c h e m i c a l c o n s t i t u e n t s i n p a t i e n t s w i t h c h r o n i c b r o n c h i t i s . The t h i c k n e s s o f t he f l u i d l a y e r has a l s o been shown t o be o f impor t ance i n c l e a r a n c e , w i t h bo th too t h i c k o r t oo t h i n a l a y e r r e s u l t i n g i n d e c r e a s e d movement o f s u r f a c e p a r t i c l e s ( 2 4 ) . The g o b l e t c e l l m e t a p l a s i a and g l a n d h y p e r t r o p h y seen i n c h r o n i c b r o n c h i t i c s r e s u l t s i n i n c r e a s e d p r o d u c t i o n o f mucus. T h i s i s r e l a t e d t o s i g n i f i c a n t a i rway o b s t r u c t i o n bu t the e f f e c t t h a t the i n c r e a s e d mucus volume i t s e l f has on c l e a r a n c e i s no t e v i d e n t . In s t u d i e s on e x c i s e d c h i c k e n t r a c h e a s , H i l d i n g (25) has demons t r a t ed t h a t mucus p l u g s o c c l u d i n g the whole a i rway lumen can s t i l l be t r a n s p o r t e d e f f e c t i v e l y by c i l i a r y movement. The o v e r a l l e f f e c t i v e n e s s o f the m u c o c i l i a r y e s c l a t o r a l s o depends on c o - o r d i n a t e d c i l i a r y b e a t i n g i n a g e n e r a l l y c e p h a l a d d i r e c t i o n . The number o f c i l i a t e d c e l l s and the r a t e o f c i l i a r y b e a t i n g i n c r e a s e s f r om p e r i p h e r a l t o c e n t r a l a i rways as does the r a t e o f the mucous t r a n s p o r t . The impor t ance o f c i l i a r y movement i n the p r e v e n t i o n o f d i s e a s e i s d e m o n s t r a t e d by i n v e s t i g a t i o n o f p e r s o n s w i t h comp le t e absence o f c i l i a r y movement, the \" i m m o t i l e - c i l i a s y n d r o m e \" , - 27 -i n whom m u c o c i l i a r y c l e a r a n c e i s s low o r a b s e n t . P a t i e n t s w i t h t h i s syndrome have been r e p o r t e d (26) t o have r e c u r r e n t upper and lower r e s p i r a t o r y t r a c t i n f e c t i o n s , f r e q u e n t b r o n c h i e c t a s i s , and somet imes , emphysema. I n h a l e d e n v i r o n m e n t a l p o l l u t a n t s can a f f e c t c i l i a r y movement, e i t h e r by p a r a l y s i s o f c i l i a o r by l o s s o f c i l i a t e d c e l l s ( 2 0 ) . C i l i o s t a s i s has been demons t r a t ed i n e x c i s e d an ima l t r a c h e a s (27) and human e p i t h e l i a l c u l t u r e s (28) a f t e r b r i e f e x p o s u r e s t o c i g a r e t t e smoke. Long- te rm exposu re to smoke r e s u l t e d i n d e c r e a s e d c i l i a r y f r e q u e n c y i n hamste rs bu t an appa ren t i n c r e a s e i n r a t s , a l t h o u g h t h e r e were f o c a l a r eas o f d i s c o o r d i n a t i o n and absence o f c i l i a r y movement ( 2 9 ) . SO^ and NO^ b o t h p roduce s i m i l a r c i l i o s t a t i c e f f e c t s w i t h b r i e f e x p o s u r e s . In a d d i t i o n t o d i s t u r b a n c e o f c i l i a r y f u n c t i o n , i n h a l a t i o n o f t h e s e s u b s t a n c e s i s a l s o r e l a t e d t o l o s s o f c i l i a t e d c e l l s as a r e s u l t o f f o c a l e p i t h e l i a l damage, and squamous and g o b l e t c e l l m e t a p l a s i a ( 2 0 ) . The d e f e n s e o f the l u n g , t h e n , a t the l e v e l o f t he t r a c h e o - b r o n c h i a l t r e e depends on the combined e f f e c t o f c i l i a r y b e a t i n g and mucus p r o d u c t i o n ; t h a t i s , the i n t e r a c t i o n o f c i l i a and mucus. T h i s has been measured i n humans and an ima l s as \" m u c o - c i l i a r y c l e a r a n c e \" by e l i m i n a t i o n o f i n h a l e d a e r o s o l s , o r \"mucus t r a n s p o r t \" by the movement o f marke rs p l a c e d i n a known l o c a t i o n on the mucosa . D i f f e r e n c e s i n t h e s e measurements may be the r e s u l t o f the deg ree o f p e n e t r a t i o n o f the t r a c e r i n t o the s u r f a c e f l u i d l a y e r o r the s u r f a c e a r e a o v e r wh i ch the t r a c e r i s d e p o s i t e d . Measurement o f m u c o c i l i a r y c l e a r a n c e o r t r a n s p o r t r a t e s i n human c i g a r e t t e smokers sugges t t h a t t h i s f u n c t i o n may be i m p a i r e d as a r e s u l t o f smoke exposu re but no t i n a l l i n d i v i d u a l s . Camner and P h i l i p s o n (30) s t u d i e d 10 p a i r s o f s m o k i n g - d i s c o r d a n t tw ins and found t h a t i n f i v e p a i r s , the smoker d i s p l a y e d i m p a i r e d c l e a r a n c e w h i l e i n the o t h e r f i v e p a i r s , t h e r e was no d i f f e r e n c e i n c l e a r a n c e r a t e s . T h i s s t udy e x e m p l i f i e s the r e s u l t s o f many i n v e s t i g a t i o n s ; t h a t i s , s t u d i e s i n d i c a t i n g s l owe r c l e a r a n c e i n smokers (31) and o t h e r s (32) wh i ch f a i l t o uncove r a d i f f e r e n c e r e l a t i n g to c i g a r e t t e smoke e x p o s u r e . In a r e v i e w o f t h e s e s t u d i e s Wanner (22) c o n c l u d e s t h a t the e v i d e n c e does i n d i c a t e impa i rment o f m u c o c i l i a r y t r a n s p o r t i n smokers wh i ch may o c c u r a f t e r as l i t t l e as one y e a r o f exposu re and may p r e cede o t h e r r e s p i r a t o r y f u n c t i o n a l a b n o r m a l i t i e s . I n h a l a t i o n o f o t h e r a t m o s p h e r i c p o l l u t a n t s may p roduce i m p a i r e d o r augmented c l e a r a n c e . Camner and co-workers s t u d i e d c a r b o n d u s t i n h a l a t i o n (33) and f o u n d i n c r e a s e d c l e a r a n c e i n some s u b j e c t s . S i m i l a r r e s u l t s were f o u n d w i t h SO,, and s u l p h u r i c a c i d i n h a l a t i o n i n e x e r c i s i n g humans, and t h i s was a t t r i b u t e d t o a r e f l e x i n c r e a s e i n s e c r e t i o n s i n the a i rways ( 3 4 , 3 5 ) . A n o t h e r s t udy (36) n o t e d t h i s i n c r e a s e d c l e a r a n c e w i t h s u l p h u r i c a c i d i n h a l a t i o n a t low c o n c e n t r a t i o n s but f o u n d d e c r e a s e d c l e a r a n c e w i t h h i g h c o n c e n t r a t i o n s . A n i m a l s t u d i e s o f l o n g - t e r m exposu re t o SO2 and N 0 2 a l s o i n d i c a t e i m p a i r e d m u c o c i l i a r y t r a n s p o r t ( 3 7 , 3 8 ) , a l t h o u g h the e f f e c t s o f NO^ were r e v e r s e d 7 days a f t e r c e s s a t i o n o f exposu re and no a i rway p a t h o l o g y was e v i d e n t i n the a n i m a l s s t u d i e d . D e l e h u n t and c o l l e a g u e s (39) exposed sheep t o a c o m b i n a t i o n o f SO and ozone - 29 -and found impaired mucus v e l o c i t y i n vivo but no change in c i l i a r y beat frequency in v i t r o . This impairment of the coordinated action of mucus and c i l i a could r e s u l t i n excessive b u i l d up of secretions and consequent airway obstruction by mucous plugging; prolonged contact of inhaled toxins or carcinogens with e p i t h e l i a l c e l l s ; and a l t e r a t i o n s i n the surface l i n i n g c h a r a c t e r i s t i c s of peripheral airways r e s u l t i n g in airway closure. b) Reflex airway defenses In addition to the entrapment and removal of inhaled p a r t i c l e s by the mucociliary mechanisms, the airways also provide a d d i t i o n a l defense against penetration of pollutants into the alv e o l a r space v i a r e f l e x mechanisms. These airway reflexes and t h e i r response to s t i m u l i represent a complex, i n t e r a c t i v e system of controls on airway c a l i b r e , rate and depth of breathing, and s p e c i a l i z e d response patterns (such as cough and sneeze) which varies with both the s i t e stimulated and the nature of the stimulation. Generally speaking they represent the i n i t i a l , immediate response to inhalation of i r r i t a n t s t i m u l i and can also serve to bring other physiologic defensive responses into play. In the airways, the \" i r r i t a n t receptors\" are myelinated, afferent f i b r e s , located between and beneath e p i t h e l i a l c e l l s (40). Physiologic studies i n animals show that these are more concentrated - 30 -in c e n t r a l airways (71% within one cm of the hilum i n dogs (41) and 54% i n cats (42)) and are stimulated by dust, gases, aerosols, and mechanical d i s t o r t i o n (42-46). Stimulation of these receptors in the larynx and trachea r e s u l t s i n cough, in which a deep i n s p i r a t i o n i s followed by a forced expiratory e f f o r t i n i t i a l l y against a closed g l o t t i s . The i n t r a t h o r a c i c pressure generated i s extremely high. The airways are narrowed, both by dynamic compression and r e f l e x bronchoconstriction r e s u l t i n g i n increased a i r f l o w and greater r i g i d i t y of the airways so that they are les s l i k e l y to collapse with the high pressure generated during the cough (47). The rapid a i r f l o w of e x p i r a t i o n r e s u l t s in transformation of the l i q u i d within the airway lumen into a mist, which i s expelled, taking deposited p a r t i c l e s along with i t . The effectiveness of coughing i n the elimination of inhaled p a r t i c u l a t e or excessive secretions i s v a r i a b l e among patients. Mossberg and colleagues (26) found that patients with the i m m o t i l e - c i l i a syndrome could eliminate t e s t p a r t i c l e s by 1-2 minutes of coughing with an e f f i c i e n c y varying from 2 to 48% . Camner and colleagues (48) found that such elimination of test p a r t i c l e s was possible only i n patients with symptomatic phlegm and expectoration and that healthy subjects could not expel these with voluntary coughing. On the other hand, cough in patients with obstructed airways may be i n e f f e c t i v e i n removing secretions as the narrowed airways may close as a r e s u l t of the high compression forces in the chest during coughing. - 31 -Cough r e c e p t o r s may be s t i m u l a t e d by v a r i o u s s t i m u l i i n c l u d i n g i n f l a m m a t i o n , m e c h a n i c a l o r c h e m i c a l i r r i t a t i o n , o r t h e r m a l s t i m u l a t i o n ( i e : c o l d a i r ) . The impor t ance o f cough as a d e f e n s i v e mechanism i s u n d e r s c o r e d by the p o t e n t i a l f o r l ower r e s p i r a t o r y t r a c t i n f e c t i o n i n p a t i e n t s u n a b l e t o c o u g h . The p h y s i o l o g i c r e s p o n s e s r e s u l t i n g f r om s t i m u l a t i o n o f \" i r r i t a n t r e c e p t o r s \" i n the s m a l l e r a i rways a re not c o m p l e t e l y u n d e r s t o o d . S t u d i e s i n a n a e s t h e t i z e d a n i m a l s sugges t t h a t r a p i d s h a l l o w b r e a t h i n g and b r o n c h o c o n s t r i c t i o n may r e s u l t f rom s t i m u l a t i o n o f t he se r e c e p t o r s i n the l u n g (42) bu t the s i g n i f i c a n c e o f t h e s e t o human p h y s i o l o g y i s no t c l e a r . R a p i d s h a l l o w b r e a t h i n g does no t appear t o o c c u r i n humans exposed to i r r i t a n t s and the r o l e o f v a g a l l y m e d i a t e d ne rvous s t i m u l a t i o n i n the b r o n c h o c o n s t r i c t i o n a s s o c i a t e d w i t h a i rway h y p e r - r e a c t i v i t y i s c o n t r o v e r s i a l . Such a r e f l e x c o u l d , t h e o r e t i c a l l y , s e r v e a d e f e n s i v e f u n c t i o n i n p r o m o t i n g d e p o s i t i o n o f p a r t i c l e s i n l a r g e r a i r w a y s , a l t h o u g h i t s p r a c t i c a l v a l u e i s d e b a t a b l e . C i g a r e t t e smoke i n h a l a t i o n i n b o t h c h r o n i c smokers and non-smokers p roduces an immediate b r o n c h o c o n s t r i c t o r y r e s p o n s e (49) bu t t h i s i s not a c o n s i s t e n t f i n d i n g and r e g u l a r c i g a r e t t e smokers appear t o be a b l e t o m o d i f y t h e i r smoke i n h a l a t i o n t o overcome t h i s r e a c t i o n ( 5 0 ) . c ) Removal by b l o o d o r l y m p h a t i c s C l e a r a n c e o f m a t e r i a l d e p o s i t e d i n the a i rways by movement - 32 -t h r o u g h the e p i t h e l i u m i s l e s s e n e d by the f a c t t h a t a i rway e p i t h e l i a l c e l l s a re a t t a c h e d t o each o t h e r a t t h e i r a p i c e s by a \" t i g h t j u n c t i o n \" network wh i ch n o r m a l l y r e n d e r s the e p i t h e l i u m impermeable t o a l l b u t the s m a l l e s t m o l e c u l e s ( 5 1 ) . However s e v e r a l i n v e s t i g a t o r s ( 52 ,53 ) have shown t h a t t h i s b a r r i e r i s b roken down and the e p i t h e l i u m becomes much more permeab le t o mac romo l e cu l e s i n the p r e s e n c e o f an i n f l a m m a t o r y r e s p o n s e i n the a i r w a y . T h i s w i l l be d i s c u s s e d more f u l l y i n the f o l l o w i n g s e c t i o n s . As a c l e a r a n c e r o u t e , however , i t has been d e m o n s t r a t e d t h a t the m a j o r i t y o f m a t e r i a l wh i ch p e n e t r a t e s the a i rway e p i t h e l i u m as a r e s u l t o f i n c r e a s e d p e r m e a b i l i t y , and wh i ch i s s u b s e q u e n t l y removed f rom the l u n g , i s c l e a r e d by the b l o o d s t r e a m r a t h e r than by l y m p h a t i c s ( 5 4 ) . I t i s no t known whether s i g n i f i c a n t m a t e r i a l becomes s e q u e s t e r e d i n the t i s s u e o r i n t i s s u e macrophages as a r e s u l t o f t h i s e p i t h e l i a l p e n e t r a t i o n . 3. A l v e o l a r C l e a r a n c e I n h a l e d s u b s t a n c e s t h a t r e a c h a l v e o l a r spaces may be c l e a r e d by one o r more o f s e v e r a l mechan isms : s o l u b i l i z a t i o n , t r a n s p o r t and e l i m i n a t i o n v i a the b l o o d s t r e a m o r l y m p h a t i c s , o r t r a n s f e r t o and r emova l by the m u c o c i l i a r y e s c a l a t o r . In v i v o s o l u b i l i t y o f s u b s t a n c e s w i t h i n the l u n g has been s t u d i e d by compar ing the s o l u b i l i t y o f s u b s t a n c e s i n j e c t e d i n t o musc l e t o t h e i r r a t e o f d i s a p p e a r a n c e i n the l u n g . Morrow and a s s o c i a t e s (55) f o u n d t h a t r e t e n t i o n o f a w ide v a r i e t y o f m e t a l o x i d e s and o t h e r - 33 -m e t a l l i c p a r t i c l e s i n the l u n g parenchyma c o r r e l a t e d w i t h r e t e n t i o n i n musc l e and w i t h u l t r a f i l t r a t i o n c h a r a c t e r i s t i c s i n v i t r o . In a d d i t i o n , o t h e r s (56 ,57 ) have f o u n d a c o r r e l a t i o n between l o n g - t e r m r e t e n t i o n o f p a r t i c l e s and i n - v i t r o s o l u b i l i t y . However , w h i l e d i s s o l u t i o n may be a s i g n i f i c a n t c l e a r a n c e mechanism i n some c a s e s , i t c anno t e x p l a i n the c l e a r a n c e p a t t e r n s f o r h i g h l y i n s o l u b l e p a r t i c l e s . C l e a r a n c e o f i n h a l e d p a r t i c l e s by t r a n s f e r t o the l y m p h a t i c s has been s t u d i e d by s e v e r a l worke rs (58-60) who have done s e r i a l i n v e s t i g a t i o n s i n an ima l s f o l l o w i n g i n s t i l l a t i o n o r i n j e c t i o n o f p a r t i c l e s i n c l u d i n g c o l l o i d a l c a r b o n , f e r r i t i n , and i r o n o x i d e . These s t u d i e s i n d i c a t e t h a t p a r t i c l e s c r o s s the a l v e o l a r e p i t h e l i u m and appear i n the i n t e r s t i t i a l c o n n e c t i v e t i s s u e . The mechanism whereby p a r t i c l e s t r a v e r s e the e p i t h e l i u m i s no t c o m p l e t e l y known. Some a u t h o r s have p r o v i d e d m o r p h o l o g i c e v i d e n c e o f t r a n s p o r t a c r o s s Type I a l v e o l a r e p i t h e l i a l c e l l s , where the p a r t i c l e s appear i n v e s i c l e s ( 5 9 ) . O t h e r s t u d i e s u s i n g p r o t e i n t r a c e r s (60) have i n d i c a t e d t h a t a p a r a c e l l u l a r pathway may be s i n g i f i c a n t , p a r t i c u l a r l y i f the e p i t h e l i a l t i g h t j u n c t i o n s a re damaged by i r r i t a n t s such as N 0 2 o r c i g a r e t t e smoke. Once a c r o s s the e p i t h e l i u m , however , the p a r t i c l e s t hen appear i n the pu lmonary l y m p h a t i c s where they a re seen b o t h w i t h i n the l y m p h a t i c lumena and i n v e s i c l e s i n the l y m p h a t i c e n d o t h e l i a l c e l l s ( 5 9 , 6 1 ) . The r e l a t i v e impor t ance o f t r a n s p o r t o f i n h a l e d p a r t i c u l a t e s t h r o u g h the i n t e r s t i t i u m and i n t o l y m p h a t i c v e s s e l s (wh ich do not r e a c h as f a r as the a l v e o l i ) i s no t c l e a r . T o t a l l u n g lymph f l o w i s v e r y low and the mechanism o f t r a n s p o r t o f - 34 -p a r t i c l e s through the i n t e r s t i t i u m i s also unknown although t i s s u e f l u i d movement r e s u l t i n g from negative hydrostatic pressure has been postulated (58). I t has been assumed that the amount of inhaled or i n s t i l l e d p a r t i c l e s seen in regional lymph nodes represents the amount cleared v i a lymphatics. This ranges from n e g l i g i b l e (62) to about f i v e percent of the lung burden (63) depending on the i n i t i a l lung burden and the s i z e and composition of the p a r t i c l e s . These figures may in fa c t under-represent the case, as the lymph nodes may not completely f i l t e r out a l l p a r t i c l e s c a r r i e d by the lymph. The transport of material ingested by alveolar macrophages from the alveolar space into the lymphatics has not been c l e a r l y demonstrated. Lauweryns and Baert (58) described the accumulation of both carbon and f e r r i t i n p a r t i c l e s i n macrophages in the i n t e r s t i t i u m but d i d not observe actual passage of these c e l l s through the e p i t h e l i a l layer. I t has been suggested by Brain and associates (64) that p a r t i c l e - c o n t a i n i n g phagocytes within the i n t e r s t i t i u m most l i k e l y represent resident macrophages which have ingested free material which passed through the epithelium. Clearance v i a the bloodstream appears to be s i g n i f i c a n t only for very small p a r t i c l e s which are not taken up by macrophages. Meyer and h i s colleagues (65) i n s t i l l e d albumin into dog lungs and found a blood/lymph removal r a t i o of 6.3 to 1 and l i t t l e evidence of airway clearance. Lauweryns and Baert (58) however, found no evidence of carbon uptake into pulmonary c a p i l l a r i e s and only occasional f e r r i t i n molecules were seen along endothelial c e l l junctions and in - 35 -m i c r o p i n o c y t o t i c v e s i c l e s . M i g r a t i o n o f a l v e o l a r macrophages i n t o the b l o o d i s b e l i e v e d t o be v e r y u n l i k e l y g i v e n the n a t u r e o f the b l o o d - a i r b a r r i e r and the l a c k o f e v i d e n c e o f b l o o d a c t i v i t y i n s t u d i e s w i t h i n h a l e d r a d i o a c t i v e i n s o l u b l e p a r t i c l e s ( 6 4 ) . A n o t h e r p o s s i b l e r o u t e o f c l e a r a n c e f o r i n h a l e d p a r t i c l e s i n g e s t e d by macrophages i s t r a n s p o r t t o the c i l i a t e d e p i t h e l i u m o f the a i rways and passage mouthward on the m u c o c i l i a r y e s c a l a t o r . As w i t h the o t h e r modes o f a l v e o l a r c l e a r a n c e , t h e r e i s c o n s i d e r a b l e deba t e as t o the mechanism and s i g n i f i c a n c e o f t h i s r o u t e . I t i s known t h a t most p a r t i c l e s d e p o s i t e d i n the a l v e o l i a r e i n g e s t e d by a l v e o l a r macrophages but how t h e s e c e l l s m i g r a t e toward the b r o n c h i o l a r s u r f a c e s i s no t known, a l t h o u g h s e v e r a l mechanisms have been s u g g e s t e d . These a re r e v i ewed by B r a i n , Godesk i and S o r o k i n (64) and i n c l u d e f o l l o w i n g a c o n c e n t r a t i o n g r a d i e n t o f c h e m o t a c t i c f a c t o r , random movement, and p a s s i v e f o l l o w i n g o f a l v e o l a r f l u i d c u r r e n t s . K i l b u r n , on the o t h e r h a n d , has p r o p o s e d (66) t h a t macrophages p r e s e n t i n d i s t a l a l v e o l i r e p r e s e n t a p o p u l a t i o n t h a t does n o t , e x c e p t by i n f r e q u e n t random movement, i n t e r a c t w i t h the m u c o c i l i a r y e s c a l a t o r , bu t r a t h e r depends on d i g e s t i o n o r s o l u b i l i z a t i o n t o remove the p a r t i c l e s . He p o s t u l a t e s a second p o p u l a t i o n o f macrophages wh i ch s i e v e s t h r o u g h t e r m i n a l and r e s p i r a t o r y a i rway w a l l s and i s c l e a r e d by mucous t r a n s p o r t . Most i n v e s t i g a t i o n s , however , sugges t t h a t t h e r e i s some i n t r a l u m e n a l t r a n s l o c a t i o n o f d u s t l a d e n macrophages f rom a l v e o l i toward the c i l i a t e d e p i t h e l i u m . S o r o k i n and B r a i n (59) s t u d i e d the r emova l o f - 36 -i r o n oxide p a r t i c l e s from mouse lungs at i n t e r v a l s up to fourteen months a f t e r a s i n g l e exposure. Macrophages appear i n increased numbers on the a l v e o l a r surface by one hour a f t e r exposure and a c t i v e l y ingest the p a r t i c l e s . Both e x t r a c e l l u l a r and c e l l u l a r mechanisms were b e l i e v e d to be r e s p o n s i b l e f o r movement of p a r t i c l e s toward bronchioles w i t h a t r a n s i e n t r e t a r d a t i o n of movement at the airway a l v e o l a r j u n c t i o n before moving i n t o the b r o n c h i o l a r lumen. Again, the importance of t h i s route depends on the nature of the inh a l e d substance. For example, w i t h the i n h a l a t i o n of c y t o t o x i c s i l i c a p a r t i c l e s , macrophages are damaged and the f r e e p a r t i c l e s may penetrate to the i n t e r s t i t i u m more f r e e l y . This concept i s supported by s t u d i e s i n which a c o r r e l a t i o n was found between the amount of p a r t i c l e s c l e a r e d r a p i d l y v i a airways and the number of macrophages present (67) and stu d i e s i n which the clearance of s i l i c a was increased when i t s c y t o t o x i c i t y was reduced by p o l y v i n y l p y r i d i n e - N - o x i d e a d m i n i s t r a t i o n (63). In g e n e r a l , a l v e o l a r clearance of i n h a l e d p a r t i c l e s i n humans appears to be extremely slow. A f t e r an i n i t i a l r a p i d clearance phase during the f i r s t 24 hours, clearance h a l f - t i m e s are reported as long as s e v e r a l months ( 5 ) . The i n i t i a l phase i s thought to be ass o c i a t e d w i t h f l u i d flow and movement of a l v e o l a r macrophages to b r o n c h i o l a r w a l l s w i t h subsequent m u c o c i l i a r y clearance. D i s s o l u t i o n and removal of p a r t i c l e s v i a i n t e r s t i t i a l pathways may account f o r a second phase of clearance. There remains however, a f r a c t i o n of the in h a l e d lung burden f o r which no apparent clearance mechanisms e x i s t . This - 37 -f r a c t i o n i s p r e s e n t l a r g e l y w i t h i n macrophages wh i ch a re no t c l e a r e d by m u c o c i l i a r y a c t i o n i n the a i rways and c o u l d p r e s e n t a c o n c e n t r a t i o n phenomenon wh i ch may be h a r m f u l i n t h a t t o x i c o r c a r c i n o g e n i c s u b s t a n c e s become l o c a l i z e d and c o n c e n t r a t e d . B r a i n and h i s c o l l e a g u e s (64) s u g g e s t t h a t some o f t h e s e macrophages wh ich do no t c l e a r f rom the l u n g become adhe ren t t o the a i rway e p i t h e l i u m and may r e l e a s e t h e i r c o n t e n t s w i t h subsequent up take by s u b e p i t h e l i a l c o n n e c t i v e t i s s u e mac rophages . These c e l l s a r e s i t u a t e d such t h a t t hey a re c l o s e l y a s s o c i a t e d w i t h c e l l s o f the immunolog ic d e f e n s e s y s t e m . S t i r l i n g and P a t r i c k (68) a l s o f o u n d m a c r o p h a g e - a s s o c i a t e d e p i t h e l i a l p e n e t r a t i o n o f BaSO^ p a r t i c l e s i n r a t t r a c h e a i n a r ea s o f n o n - c i l i a t e d , c u b o i d a l o r squamous e p i t h e l i a l c e l l s wh i ch were i n f i l t r a t e d by a c o n s p i c u o u s number o f l y m p h o c y t e s . I n c r e a s e d e p i t h e l i a l p e r m e a b i l i t y may p l a y a r o l e i n t h i s k i n d o f t r a n s - e p i t h e l i a l p a r t i c l e movement. The e f f e c t i v e n e s s o f a l v e o l a r c l e a r a n c e mechanisms can be a l t e r e d by i n h a l a t i o n o f v a r i o u s a g e n t s . F e r i n and Leach (62) f ound t h a t about 40% o f i n h a l e d T i O ^ p a r t i c l e s were c l e a r e d w i t h i n 25 days o f exposu re and t h a t t h i s was m a i n l y due t o a l v e o l a r macrophage i n v o l v e m e n t . Exposu re t o low c o n c e n t r a t i o n s o f SO^ and N O x enhanced t h i s c l e a r a n c e whereas h i g h e r c o n c e n t r a t i o n s d e p r e s s e d c l e a r a n c e o f the T i O ^ . In g e n e r a l i t appea rs t h a t s u b s t a n c e s wh i ch a c t i v a t e and/o r r e c r u i t macrophages w i l l a i d macrophage a s s o c i a t e d c l e a r a n c e ( 5 7 ) . C o n v e r s e l y , i n h a l a t i o n o f s u b s t a n c e s wh i ch damage the macrophage such - 38 -t h a t i t s c a p a c i t y f o r p h a g o c y t o s i s i s d i m i n i s h e d r e n d e r the l u n g more l i a b l e t o i n f e c t i o n o r damage due t o r e t e n t i o n o f an i n c r e a s e d bu rden o f p a r t i c u l a t e . Ozone , h i g h oxygen c o n c e n t r a t i o n s , and c i g a r e t t e smoke have a l l been shown to d e c r e a s e the b a c t e r i a c i d a l c a p a c i t y o f macrophages ( 6 9 ) . S i l i c a exposu re i s c y t o t o x i c t o macrophages and s i l i c a d u s t i s c l e a r e d much more s l o w l y than i n e r t p a r t i c l e s ( 6 3 ) . Long t e rm exposu re t o s i l i c a i s a l s o a s s o c i a t e d w i t h an i n c r e a s e d i n c i d e n c e o f t u b e r c u l o s i s i n f e c t i o n ( 6 9 ) . S t u d i e s c a r r i e d ou t by Camner and a s s o c i a t e s i n r a b b i t s , however , f o u n d t h a t i n v i v o c l e a r a n c e o f t e l f l o n p a r t i c l e s c o a t e d w i t h s i l v e r , c a r b o n , o r b e r y l l i u m d i d not d i f f e r d e s p i t e the f a c t t h a t b e r y l l i u m c o a t e d p a r t i c l e s were more t o x i c t o macrophages i n v i t r o ( 7 0 ) . The n o r m a l l y low p e r m e a b i l i t y o f the a l v e o l a r - c a p i l l a r y membrane p r e v e n t s s i g n i f i c a n t b l o o d s t r e a m c l e a r a n c e f o r a l l bu t v e r y s m a l l p a r t i c l e s . T h i s p e r m e a b i l i t y has been shown to be s i g n i f i c a n t l y i n c r e a s e d a f t e r c i g a r e t t e smoke exposu re ( 7 1 ) . Whether t h i s has impor t ance f o r c l e a r a n c e o f l a r g e r p a r t i c u l a t e s remains t o be d e t e r m i n e d . In summary, the mechanisms wh ich may be b rough t i n t o p l a y t o d e f e n d the v e r y d e l i c a t e a l v e o l i f rom i n h a l e d s u b s t a n c e s a re no t as w e l l u n d e r s t o o d as t h o s e o f the a i r w a y s . They appear t o o p e r a t e much more s l o w l y and l e s s e f f i c i e n t l y t han n a s a l o r t r a c h e o - b r o n c h i a l d e f e n s e s . Thus the p o t e n t i a l f o r l u n g i n j u r y i s i n c r e a s e d when the a i rway d e f e n s e s a re b y p a s s e d o r ove rcome. - 39 -REFERENCES - CHAPTER I I I 1. Huber GL , F i r s t MW: P e r s p e c t i v e s : pu lmonary h o s t d e f e n s e s , the h o s t , and the deve lopment o f l u n g d i s e a s e . Sem Resp Med 1980 ; 1:187-196 2. P r o c t o r DF : The upper a i r w a y s . 1. N a s a l p h y s i o l o g y and d e f e n s e o f t h e l u n g s . Am Rev R e s p i r D i s 1977 , 115 :97-129 3. Hayash i M, Huber GL : A i rways d e f e n s e s . 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S t r e c h k e r F I : T i s s u e r e a c t i o n s i n r a t l u n g s a f t e r d u s t i n h a l a t i o n w i t h s p e c i a l r e g a r d t o b r o n c h i a l d u s t e l i m i n a t i o n and t o the p e n e t r a t i o n o f d u s t i n t o the l u n g i n t e r s t i c e s and l y m p h a t i c n o d e s . I n : D a v i e s CN , e d , I n h a l e d P a r t i c l e s and Vapours I I . O x f o r d : Pergamon P r e s s , 1967:141-152 64 . B r a i n JD , G o d l e s k i J J , S o r o k i n SP: Q u a n t i f i c a t i o n , o r i g i n , and f a t e o f pu lmonary mac rophages . I n : B r a i n JD , P r o c t o r DF , R e i d LM, e d s , R e s p i r a t o r y De fense Mechanisms New Y o r k : M a r c e l Dekker 1977:849-892 - 46 -6 5 . Meyer EC , O t t a v i a n o R, H i g g i n s J J : A lbumin c l e a r a n c e f r o m a l v e o l i : t i s s u e p e r m e a t i o n vs a i rway d i s p l a c e m e n t . J A p p l P h y s i o l 1977 ; 43 :487-497 66 . K i l b u r n KH: C l e a r a n c e zones i n the d i s t a l l u n g . Ann NY Acad S c i 1974 ; 221:276-281 6 7 . F e r i n J : E l i m i n a t i o n o f d u s t f rom the l u n g and the i n f l u e n c e o f the r e t i c u l o e n d o t h e l i a l s y s t e m . Ann Occup Hyg 1960 ; 3:1-5 6 8 . S t i r l i n g C , P a t r i c k G: The l o c a l i z a t i o n o f p a r t i c l e s r e t a i n e d i n the t r a c h e a o f the r a t . J P a t h o l 1980 ; 131 :309-320 6 9 . A l l i s o n A C : Mechanisms o f macrophage damage i n r e l a t i o n t o the p a t h o g e n e s i s o f some l u n g d i s e a s e s . I n : B r a i n JD , P r o c t o r DF , R e i d LM, e d s , R e s p i r a t o r y De fense Mechanisms New Y o r k : M a r c e l Dekker 1977:1075-1102 70 . Cramner P, H e l l s t r o m P-A, Lundborg M, P h i l i p s o n K: Lung c l e a r a n c e o f 4-urn p a r t i c l e s c o a t e d w i t h s i l v e r , c a r b o n , o r b e r y l l i u m . A r c h E n v i r o n H e a l t h 1977 ; 32 :58-62 71 . Jones J G , L aw l e r P, C raw ley JCW, M i n t y BD, Hu lands G , V e a l l N: I n c r e a s e d a l v e o l a r e p i t h e l i a l p e r m e a b i l i t y i n c i g a r e t t e smokers . The L a n c e t 1980 ; 1:66-68 - 47 -IV. The Lung Response and the I n f l ammato ry P r o c e s s The p r e c e d i n g c h a p t e r s have r e v i e w e d the f a c t o r s , b o t h e x t e r n a l and i n t e r n a l , wh i ch i n f l u e n c e d e p o s i t i o n and r e t e n t i o n o f i n h a l e d n o x i o u s a g e n t s . The l u n g r e s p o n s e , t h a t i s , whether o r no t exposu re t o t h e s e agen ts r e s u l t s i n l u n g damage o r d i s e a s e , depends o n l y i n p a r t on t h e s e d e p o s i t i o n and r e t e n t i o n c h a r a c t e r i s t i c s . E q u a l l y i m p o r t a n t i s the a c t i v i t y o f the agent i n the l u n g , the n a t u r e o f the i n j u r y r e s u l t i n g f rom r e t e n t i o n and whether o r no t the exposu re p rovokes an i n f l a m m a t o r y r e s p o n s e . The i n i t i a l r e s p o n s e o f the l u n g t i s s u e t o an i n h a l e d t o x i c a e r o s o l o r gas depends l a r g e l y on the n a t u r e o r c h e m i c a l a c t i v i t y o f t he agent and many d i v e r s e t y p e s o f i n j u r y may o c c u r . These c a n be c h a r a c t e r i z e d as i n j u r y due t o a s p h y x i a t i o n , s y s t e m i c t o x i c i t y , r e f l e x r e s p o n s e s , s p e c i f i c o r n o n - s p e c i f i c immunolog ic mechan isms , o r d i r e c t mucosa l o r a l v e o l a r damage. A s p h y x i a t i o n o c c u r s when the oxygen i n a l v e o l a r a i r i s r e p l a c e d by a gas no t n o r m a l l y t o x i c ( f o r examp le , by CO^, N^, o r CH^ as can o c c u r i n an unde rg round m i n i n g e n v i r o n m e n t ) . A l t e r n a t e l y , t i s s u e a s p h y x i a can o c c u r as a r e s u l t o f i n a b i l i t y o f a t i s s u e t o o b t a i n o r u t i l i z e 0^, i f the 0^ c a r r y i n g c a p a c i t y o f the b l o o d i s d e c r e a s e d ( e . g . by CO o r HS) o r i f the r e s p i r a t o r y enzyme systems o f the c e l l s a r e p o i s o n e d (as w i t h c y a n i d e ) . T h i s l a t t e r example c o u l d a l s o be te rmed damage due t o s y s t e m i c t o x i c i t y . A n o t h e r - 48 -example o f agents b e i n g a b s o r b e d v i a the a l v e o l i and c a u s i n g s y s t e m i c d i s e a s e i s b e l i e v e d t o o c c u r i n \" m e t a l fume f e v e r \" and \" p o l y m e r fume f e v e r \" . In t h e s e d i s o r d e r s an i n f l u e n z a - l i k e c o n d i t i o n o c c u r s f o l l o w i n g exposu re t o the v e r y s m a l l p y r o l y s i s p r o d u c t s p r o d u c e d d u r i n g the h e a t i n g o f c e r t a i n m e t a l s o r t e t r a f l u o r o e t h y l e n e r e s i n s ( 1 ) . C e r t a i n i n h a l a n t s may p rovoke i n j u r y by r e f l e x mechanisms a s s o c i a t e d w i t h a i rway i r r i t a n t r e c e p t o r s . S u l p h u r d i o x i d e gas (2) and p a r t i c l e s o f c h a r c o a l (3) have been r e p o r t e d t o d i r e c t l y s t i m u l a t e a i rway r e c e p t o r s r e s u l t i n g i n a i rway smooth musc l e c o n s t r i c t i o n . S t i m u l a t i o n o f i r r i t a n t r e c e p t o r s has a l s o been i m p l i c a t e d i n the d e l a y e d b r o n c h o c o n s t r i c t i o n wh ich f o l l o w s exposu re t o h i g h c o n c e n t r a t i o n s o f v a r i o u s t o x i c gases and a e r o s o l s . T h i s i s , however , b e l i e v e d t o be s e c o n d a r y t o an i n f l a m m a t o r y r e s p o n s e , r a t h e r than a d i r e c t r e f l e x e f f e c t . T h i s w i l l be d i s c u s s e d l a t e r i n t h i s and subsequen t c h a p t e r s . Immunologic mechanisms can a l s o r e s u l t i n l u n g i n j u r y . One example o f s p e c i f i c a n t i g e n d i r e c t e d immune r e s p o n s e s i s the a n t i g e n - i n d u c e d m e d i a t o r r e l e a s e f rom a i rway mast c e l l s (4) r e s u l t i n g i n b r o n c h o c o n s t r i c t i o n i n wh i ch s p e c i f i c r e a g i n i c a n t i b o d i e s a r e i m p l i c a t e d . A l l e r g e n s wh i ch may be a s s o c i a t e d w i t h t h i s t ype o f s p e c i f i c r e s p o n s e i n c l u d e g r a i n d u s t s , a n i m a l p r o d u c t s , i n s e c t p r o t e i n s , B - s u b t i l i s enzymes , gum a c a c i a , and c a s t o r o i l bean ( 1 ) . O t h e r i n h a l e d a l l e r g e n s a s s o c i a t e d w i t h f u n g a l spo re s and a v i a n p r o t e i n s may p rovoke a s p e c i f i c immune r e s p o n s e i n the a l v e o l i r e s u l t i n g i n the syndrome o f h y p e r s e n s i t i v i t y p n e u m o n i t i s o r e x t r i n s i c - 49 -a l l e r g i c a l v e o l i t i s ( 1 ) . However t h i s d i s e a s e has f e a t u r e s wh i ch sugges t the a d d i t i o n a l i n vo l v emen t o f non- immunlog ic mechan isms . T h i s i s a l s o t r u e o f the asthma o r b r o n c h o c o n s t r i c t i o n p r o d u c e d by i n h a l a t i o n o f a w ide v a r i e t y o f c h e m i c a l s , m e t a l s and wood .dus t s (5) i n wh i ch a d i r e c t , s p e c i f i c immune r e s p o n s e i s o n l y p a r t l y i m p l i c a t e d . Immunologic mechanisms have a l s o been p o s t u l a t e d i n the p r o g r e s s i o n o f the pneumocon ioses ( 6 ) , and a h i g h l e v e l o f c i r c u l a t i n g a n t i n u c l e a r a n t i b o d i e s has been found i n pe r sons w i t h s i l i c o s i s (7). Few gases a re c o n s i d e r e d t o be a n t i g e n i c , however v i n y l c h l o r i d e monomer gas i n h a l a t i o n i s s t r o n g l y a s s o c i a t e d w i t h immune complex a g g r e g a t i o n ( 8 , 9 ) . D i r e c t i n j u r y o r s t i m u l a t i o n o f c e l l s o f l u n g t i s s u e a c c o u n t s f o r a good d e a l o f i n i t i a l l u n g i n j u r y , e i t h e r by a l t e r i n g c e l l u l a r m e t a b o l i s m o r p r o d u c i n g c e l l d e a t h and t i s s u e n e c r o s i s . In the a i r w a y s , agen ts such as ammonia and a l d e h y d e s (10) have been a s s o c i a t e d w i t h a l t e r a t i o n s i n the r e g u l a t i o n o f t r a n s p o r t o f wa te r and i o n s by e p i t h e l i a l c e l l s and N0^ i n h a l a t i o n (11) a s s o c i a t e d w i t h c i l i a r y a l t e r a t i o n . Bo th t h e s e e f f e c t s may i n f l u e n c e m u c o c i l i a r y c l e a r a n c e a c t i v i t y i n the a i r w a y s . Ozone , 0^ , and NO^ may have an o x i d a n t e f f e c t damaging membranes o f Type I pneumocytes and e n d o t h e l i a l c e l l s ( 1 2 ) . In low c o n c e n t r a t i o n s s i l i c a i n h a l a t i o n r e c r u i t s and a c t i v a t e s macrophages (6 ,13 ) w h i l e i n h i g h e r d o s e s , i n v i t r o , i t i s c y t o t o x i c t o a l v e o l a r macrophages (14) and t o Type I and Type I I pneumocytes ( 1 5 ) . T h i s c a t a l o g u e o f i n j u r i o u s e f f e c t s i s not i n t e n d e d t o be - 50 -a l l - i n c l u s i v e but r a t h e r t o i n d i c a t e the d i v e r s i t y o f the i n i t i a l c e l l u l a r o r t i s s u e i n j u r i e s wh i ch may be a s s o c i a t e d w i t h i n h a l a t i o n o f p o l l u t a n t s . I f exposu re i s m i n i m a l , the t i s s u e r e s p o n s e may be such t h a t c e l l s a r e a l t e r e d bu t t hen r e t u r n t o t h e i r norma l s t a t e when e x p o s u r e c e a s e s . However , i f exposu re i s p r o l o n g e d , i f the c o n c e n t r a t i o n i s h i g h , o r i f the agent i s e s p e c i a l l y t o x i c , then the i n j u r y , whether i t i s d i r e c t o r i n d i r e c t , and r e g a r d l e s s o f i t s n a t u r e , c a l l s f o r t h an i n f l a m m a t o r y r e s p o n s e wh i ch i s no t s p e c i f i c t o e i t h e r the agent o r the k i n d o f i n j u r y . The i n i t i a l i n j u r i o u s even t may be d i r e c t o r i n d i r e c t damage t o b r o n c h i o l a r o r a l v e o l a r e p i t h e l i a l c e l l s , damage o r s t i m u l a t i o n o f immune o r i n f l a m m a t o r y c e l l s r e s i d e n t i n the l u n g , o r a n t i g e n i c c h a l l e n g e ; the common a n t e c e d e n t o f a l l o f t he se t y p e s o f i n j u r y i s the r e c r u i t m e n t o f immune and i n f l a m m a t o r y c e l l s f rom the c i r c u l a t i o n and the deve lopment o f an i n f l a m m a t o r y r e s p o n s e wh ich has the p o t e n t i a l f o r g r e a t e r t i s s u e damage. M e d i a t o r s r e l e a s e d f r o m i n j u r e d o r a c t i v a t e d c e l l s d i f f u s e i n t o the c i r c u l a t i o n and i n i t i a t e t h i s r e s p o n s e . The b a s i c f e a t u r e s o f the a cu t e i n f l a m m a t o r y r e s p o n s e a r e n o n - s p e c i f i c even as t o the t i s s u e i n v o l v e d . These i n c l u d e the e x u d a t i o n o f f l u i d f r om the s m a l l v e s s e l s i n the i n j u r e d a r e a as w e l l as the e m i g r a t i o n o f wh i t e b l o o d c e l l s , n o t a b l y p o l y m o r p h o n u c l e a r l e u k o c y t e s (PMN) f r om the c i r c u l a t i o n and t h e i r a g g r e g a t i o n and a c t i v a t i o n i n t he t i s s u e . T h i s a cu t e r e s p o n s e may r e s o l v e , w i t h the e x u d a t i v e d e b r i s b e i n g c l e a r e d up by a s m a l l number o f macrophages o r - 51 -i t may p e r s i s t , becoming c h r o n i c . The c h r o n i c r e s p o n s e i s somewhat more dependent on the n a t u r e o f the i n j u r i o u s a g e n t . I f the agent i s a n t i g e n i c t h e r e may be a s p e c i f i c l y m p h o c y t i c and p l asma c e l l r e s p o n s e , whereas i f the agent i s no t a n t i g e n i c the c e l l s w i l l be p r e d o m i n a n t l y mac rophages . I f the p r e c i p i t a t i n g agent i s c h e m o t a c t i c f o r PMN's i t s e l f and i f i t p e r s i s t s , the r e s u l t i n g h i s t o l o g i c a l appea rance w i l l i n c l u d e c e l l s t y p i c a l o f b o t h the a cu t e and c h r o n i c r e p o n s e . The d e t a i l s o f t h e s e c e l l u l a r and v a s c u l a r e v e n t s i n v o l v e d i n the i n f l a m m a t o r y r e s p o n s e have been r e v i ewed a t l e n g t h r e c e n t l y ( 1 6 , 1 7 , 1 8 ) . The impor t ance o f the i n f l a m m a t o r y r e s p o n s e and i n p a r t i c u l a r o f m e d i a t o r r e l e a s e f r om i n f l a m m a t o r y c e l l s was r e c o g n i z e d as e a r l y as 1887 (19) by M e c h i n k o f f , who p r o p o s e d t h a t \" f e r m e n t s \" r e l e a s e d f r o m c e l l s i n i n f l a m e d t i s s u e were r e s p o n s i b l e f o r t i s s u e damage. M e d i a t o r s p r e s e n t i n l u n g wh i ch may i n i t i a t e an i n f l a m m a t o r y r e s p o n s e a re f o u n d , i n p a r t i c u l a r , i n mast c e l l s and mac rophages ; thus a c t i v a t i o n o f t h e s e c e l l s t o r e l e a s e t h e i r c o n t e n t s whether d i r e c t l y , r e f l e x i v e l y , o r d u r i n g the p r o c e s s o f p h a g o c y t o s i s i s i m p l i c a t e d i n the deve lopment o f i n f l a m m a t i o n . Mast c e l l s a r e p r e s e n t i n a i rways i n b o t h i n t r a - and s u b - e p i t h e l i a l l o c a t i o n s ( 2 0 ) . As p r e v i o u s l y p o i n t e d o u t , m e d i a t o r r e l e a s e may o c c u r v i a a n t i g e n i c s t i m u l a t i o n o r d i r e c t l y , o r by a c o m b i n a t i o n o f bo th e f f e c t s . C o t t o n b r a c t e x t r a c t c auses h i s t a m i n e r e l e a s e f rom human l u n g t i s s u e i n v i t r o (21) p r e sumab l y by a n o n - a n t i g e n i c mechan ism, as does wes t e rn r e d c e d a r ( 2 2 ) , a l t h o u g h immuno log ic mechanisms a r e a l s o i m p l i c a t e d a t l e a s t i n the l a t t e r case - 52 -( 5 ) . The m e d i a t o r s r e l e a s e d f rom mast c e l l s i n c l u d e h i s t a m i n e , e o s i n o p h i l i c - c h e m o t a c t i c f a c t o r ( ECF-A ) , p l a t e l e t a c t i v a t i n g f a c t o r ( PAF ) , a n e u t r o p h i l c h e m o t a c t i c f a c t o r , p r o s t a g l a n d i n s , l e u k o t r i e n e s (SRS-A) and a b r a d y k i n i n - l i k e enzyme ( 4 , 1 8 , 2 3 , 2 4 ) . The r e s u l t a n t r e s p o n s e o f the l u n g i s c o n s t r i c t i o n o f b r o n c h i a l smooth m u s c l e , mucosa l edema, and the appea rance o f a PMN i n f i l t r a t e 4-6 hou r s a f t e r the edema and smooth musc l e r e s p o n s e ( 2 5 ) . Macrophages a re a l s o a p o t e n t i a l s o u r c e o f m e d i a t o r s wh i ch c o u l d p r o v i d e b o t h p o s i t i v e and n e g a t i v e f e e d b a c k t o the i n f l a m m a t o r y p r o c e s s . They c o n t a i n an i m p r e s s i v e a r r a y o f s e c r e t o r y p r o d u c t s i n c l u d i n g p r o t e a s e s , complement components , enzyme i n h i b i t o r s , r e a c t i v e oxygen m e t a b o l i t e s , b i o a c t i v e l i p i d s , and o t h e r c h e m o t a c t i c and m i t o g e n i c f a c t o r s f o r n e u t r o p h i l s , f i b r o b l a s t s , and l ymphocy t e s ( 2 6 ) . However the e f f e c t i v e , i n v i v o , pathways and p r o c e s s e s a s s o c i a t e d w i t h macrophage m e d i a t o r s a re no t w e l l c h a r a c t e r i z e d . A c t i v a t i o n o f t h e s e c e l l s i s no t a s i n g u l a r even t as d i f f e r e n t a c t i v a t i n g s t i m u l i i nduce d i f f e r e n t f u n c t i o n a l r e s p o n s e s ( 2 7 , 2 8 , 2 9 ) . A s b e s t o s exposu re r e s u l t s i n r e l e a s e o f b o t h n e u t r o p h i l c h e m o t a c t i c f a c t o r and a f i b r o b l a s t growth f a c t o r ( 2 7 , 2 8 ) ; c i g a r e t t e smoke i s r e p o r t e d t o i nduce r e l e a s e o f c h e m o t a c t i c f a c t o r f o r n e u t r o p h i l s ( 2 9 ) . The p o t e n t i a l i n v i v o s i g n i f i c a n c e o f r e l e a s e o f a n e u t r o p h i l c h e m o t a c t i c f a c t o r i s d e m o n s t r a t e d by the appearance o f a cu t e l u n g i n j u r y f o l l o w i n g i n s t i l l a t i o n o f the s u p e r n a t a n t f rom macrophage p r e p a r a t i o n s i n c u b a t e d w i t h S . a u r e u s o r o f b r o n c h i a l l a v a g e f l u i d h a r v e s t e d a f t e r i n t r a t r a c h e a l i n j e c t i o n o f t h i s o r g a n i s m ( 3 0 ) . S m a l l - 53 -amounts o f o x i d a n t s and c o n n e c t i v e t i s s u e s p e c i f i c p r o t e a s e s a r e a l s o r e l e a s e d by macrophages i n v i v o ( 3 1 ) , a l t h o u g h q u a n t i t a t i v e l y much l e s s than t h a t r e l e a s e d by PMN's . Macrophages f rom c i g a r e t t e smokers p roduce more s u p e r o x i d e than t h o s e f rom non-smokers (32) b u t c o n n e c t i v e t i s s u e s p e c i f i c p r o t e a s e r e l e a s e does no t appear t o be i n f l u e n c e d by e n v i r o n m e n t a l e x p o s u r e s ( 3 3 ) . The i n t e r - r e l a t i o n s h i p between macrophages and the immune mechanisms has been p a r t l y a t t r i b u t e d t o t he r e l e a s e by macrophages o f i n t e r l u e k i n - 1 ( 6 ) . T h i s m e d i a t o r s t i m u l a t e s b o t h T- l ymphocy t es and f i b r o b l a s t s and as such has been p r o p o s e d t o be r e s p o n s i b l e f o r s i l i c a - i n d u c e d f i b r o s i s and the i m m u n o l o g i c a l m a n i f e s t a t i o n s seen i n s i l i c o s i s ( 6 , 7 ) . Complement components a re p r e s e n t i n the l u n g a l t h o u g h t h e i r sou r ce i s no t known c o m p l e t e l y . They may be d e r i v e d f rom serum o r p r o d u c e d l o c a l l y by f i b r o b l a s t s (34) o r Type I I pneumocytes ( 3 5 ) . These components may a l s o be i n v o l v e d i n i n i t i a t i o n and p r o g r e s s i o n o f i n f l a m m a t i o n . C5a and C5a des a rg a re h i g h l y e f f e c t i v e c h e m o t a c t i c agen ts f o r n e u t r o p h i l s , as w e l l as f o r m o n o c y t e s , e o s i n o p h i l s , and b a s o p h i l s ( 1 5 ) . In a d d i t i o n they i n c r e a s e a d h e s i v e n e s s and s w e l l i n g o f PMN's (36) and s t i m u l a t e d e g r a n u l a t i o n ( 1 5 ) . I n s t i l l a t i o n o f C5 f r agments i n t o r a b b i t t r a c h e a r e s u l t s i n the p r o d u c t i o n o f an i n f l a m m a t o r y r e s p o n s e ( 3 7 , 3 8 ) . The c h e m o t a c t i c f a c t o r s r e l e a s e d by mast c e l l s , mac rophages , and o t h e r c e l l s i n the l u n g a l l a c t to r e c r u i t l a r g e numbers o f PMN's f r om the c i r c u l a t i o n i n t o the l u n g t i s s u e , e i t h e r t o a i rways o r a l v e o l i d e p e n d i n g on the l o c a t i o n o f the i n j u r y . T h i s l e u k o c y t e p l a y s - 54 -a key r o l e i n m e d i a t i n g the t i s s u e damage a s s o c i a t e d w i t h i n f l a m m a t i o n . Two i m p o r t a n t mechanisms by wh i ch t i s s u e damage has been p o s t u l a t e d i n a s s o c i a t i o n w i t h PMN f a c t o r s a re o x i d a n t i n j u r y and c o n n e c t i v e t i s s u e - s p e c i f i c p r o t e o l y t i c i n j u r y . O x i d a n t i n j u r y r e s u l t s e i t h e r f rom the a c t i o n o f m y e l o p e r o x i d a s e o r r e a c t i v e oxygen s p e c i e s wh i ch i n c l u d e s u p e r o x i d e a n i o n , h y d r o x y l r a d i c a l , s i n g l e t o x y g e n , and hyd rogen p e r o x i d e . These o x i d a t i v e a g e n t s , wh i ch a re e f f e c t i v e when d i r e c t e d a g a i n s t i n v a d i n g m i c r o - o r g a n i s m s , a re p a r t i c u l a r l y damaging i f r e l e a s e d i n t o the s u r r o u n d i n g t i s s u e s ( 39-41 ) . I t has been h y p o t h e s i z e d t h a t t h i s r e l e a s e o c c u r s when PMN's a t tempt t o p h a g o c y t i z e t i s s u e wh i ch has become c o a t e d w i t h e i t h e r s p e c i f i c a n t i b o d y o r immune complexes ( 39-42 ) . In v i v o e v i d e n c e f o r the d e s t r u c t i v e a c t i v i t y o f o x i d a n t s i n r a t l u n g s i s p r o v i d e d by Johnson and c o l l e a g u e s (43) who i n s t i l l e d e n z y m e - s u b s t r a t e sys tems known t o p roduce r e a c t i v e oxygen m e t a b o l i t e s i n t o the t r a c h e a and f o u n d e v i d e n c e o f a cu t e pa renchyma l i n f l a m m a t i o n . P r o t e o l y t i c i n j u r y t o c o n n e c t i v e t i s s u e s t r u c t u r e s i n the l u n g has been p o s t u l a t e d as i m p l i c a t e d i n the p a t h o g e n e s i s o f emphysema ( 4 4 ) . PMN's c o n t a i n abundant e l a s t a s e (45) and an i n f l u x o f t h e s e c e l l s wou ld i n c r e a s e the p o t e n t i a l e l a s t a s e l o a d on the l u n g . However , c e n t r a l t o the h y p o t h e s i s t h a t t h i s may be s i g n i f i c a n t i n the p a t h o g e n e s i s o f emphysema i s the a s s o c i a t e d d e - a c t i v a t i o n o f the major p r o t e a s e i n h i b i t o r i n the l u n g ( a l p h a ^ - a n t i p r o t e a s e ) by o x i d a n t s wh i ch can be r e l e a s e d b o t h f r om PMN's (46) and f r om macrophages ( 4 7 ) . C i g a r e t t e smoke as w e l l c o n t a i n s a l a r g e number o f o x i d a n t s (48) wh i ch - 55 -can a l s o damage a l p h a ^ - a n t i p r o t e a s e . The a b i l i t y o f d i f f e r e n t b rands o f c i g a r e t t e s to i n a c t i v a t e t h i s p r o t e a s e i n h i b i t o r has been shown t o be d i r e c t l y r e l a t e d t o the o x i d i z i n g c a p a c i t y o f the aqueous smoke s o l u t i o n and t h i s a b i l i t y i s f u r t h e r enhanced by m a c r o p h a g e - d e r i v e d p e r o x i d a s e s ( 4 9 ) . The a n t i - e l a s t a s e a c t i v i t y o f a l p h a ^ - a n t i p r o t e a s e r e c o v e r e d f rom the l u n g s o f smokers has been r e p o r t e d by Gadek and a s s o c i a t e s (48) t o be o n l y h a l f t h a t f r o m non-smokers ; however a r e c e n t r e p o r t by S tone and c o l l e a g u e s (50) has f a i l e d t o c o n f i r m t h i s f i n d i n g . S i m i l a r l y , ozone exposu re a t low c o n c e n t r a t i o n s has been r e p o r t e d t o d e c r e a s e the a n t i - e l a s t a s e a c t i v i t y i n r a t l u n g t i s s u e ( 5 1 ) . PHN e l a s t a s e has a l s o been i m p l i c a t e d i n d i s o r d e r i n g o f the r e p a i r p r o c e s s f o l l o w i n g a cu t e l u n g i n j u r y . F i b r o b l a s t s , wh i ch n o r m a l l y i n c r e a s e t h e i r r a t e o f i n t r a c e l l u l a r d e g r a d a t i o n o f newly s y n t h e s i z e d c o l l a g e n when s t i m u l a t e d by b e t a - a g o n i s t s , l o s t t h i s a b i l i t y when exposed t o PHN e l a s t a s e ( 5 2 ) . T h i s r a i s e s the p o s s i b i l i t y t h a t PHN p r o d u c t s may be s i g n i f i c a n t i n the p a t h o g e n e s i s o f f i b r o s i s i n the l u n g . Such p r o g r e s s i o n o f a cu t e i n f l a m m a t i o n t o f i b r o s i s was a l s o seen i n r a t l u n g s exposed t o o x i d a n t s ( 4 3 ) . I n f l a m m a t i o n can o c c u r i n the l u n g e i t h e r i n a l v e o l i o r i n a i rways o r bo th d e p e n d i n g on the d e p o s i t i o n s i t e o f the p r o v o k i n g a g e n t . I n h a l a t i o n o f s i l i c a , a s b e s t o s , o r c e r t a i n o r g a n i c d u s t s a s s o c i a t e d w i t h h y p e r s e n s i t i v i t y p n e u m o n i t i s (28 ,53 ) evokes an a l v e o l i t i s as an e a r l y change a s s o c i a t e d w i t h exposu re t o t h e s e a g e n t s . However , bo th s i l i c a (54) and a s b e s t o s (55 ,56 ) exposu re as - 56 -w e l l as c i g a r e t t e smoke (57-60) and many i n h a l e d e n v i r o n m e n t a l d u s t s and gases (61-63) a l s o evoke an i n f l a m m a t o r y r e s p o n s e i n the a i r w a y s , and i n p a r t i c u l a r , i n the t e r m i n a l and r e s p i r a t o r y b r o n c h i o l e s . T h i s a i rway i n f l a m m a t i o n has been i m p l i c a t e d i n the p a t h o g e n e s i s o f c h r o n i c o b s t r u c t i v e l u n g d i s e a s e i n smokers ( 5 7 , 6 0 , 6 4 , 6 5 ) and i n worke r s exposed t o p o l l u t a n t s i n t h e i r o c c u p a t i o n (34 ,56 ) as w e l l as i n the p a t h o g e n e s i s o f a i rways h y p e r - r e a c t i v i t y ( 6 6 , 6 7 ) . The s i g n i f i c a n c e o f a b n o r m a l i t i e s i n and a round t h e s e p e r i p h e r a l a i rways was p r o p o s e d as e a r l y as 1835 by Laennec ( 6 8 ) , who s u g g e s t e d t h a t o b s t r u c t i o n o f p e r i p h e r a l b r o n c h i o l e s may be r e s p o n s i b l e f o r the a i r t r a p p i n g i n emphysema. I t has o n l y been i n the l a s t two d e c a d e s , however , t h a t p h y s i o l o g i c and p a t h o l o g i c a b n o r m a l i t i e s i n t hese a i rways have been f u l l y i n v e s t i g a t e d , and i n f l a m m a t i o n a t t h i s l e v e l i d e n t i f i e d as one o f the i n i t i a l e v e n t s i n the p a t h o g e n e s i s o f pu lmonary d i s e a s e r e l a t e d t o c i g a r e t t e smoke exposu re (57-60 ) . The deve lopment o f t h i s c o n c e p t w i l l be d i s c u s s e d i n the f o l l o w i n g c h a p t e r . Recent e x p e r i m e n t a l work c a r r i e d ou t i n t h i s f i e l d by Boucher (69) and H u l b e r t (59) who i n v e s t i g a t e d i n d e t a i l the e f f e c t s o f c i g a r e t t e smoke- induced a i rway i n f l a m m a t i o n i n g u i n e a p i g s , has shown t h a t a cu t e c i g a r e t t e smoke exposu re p roduces i n c r e a s e d e p i t h e l i a l p e r m e a b i l i t y t o the t r a c e r h o r s e r a d i s h p e r o x i d a s e . T h i s i n c r e a s e i n p e r m e a b i l i t y i s a s s o c i a t e d t e m p o r a l l y w i t h the a cu te phase o f t he i n f l a m m a t o r y r e s p o n s e i n d i c a t e d by a marked i n c r e a s e i n the we t /d r y r a t i o o f the t r a c h e a and m a s s i v e PMN i n f i l t r a t e ( 5 9 ) . The PMN's a r e - 57 -f o u n d i n s i g n i f i c a n t numbers i n the mucous l a y e r w i t h i n the a i rway lumen as w e l l as i n the a i rway w a l l . These f i n d i n g s , o f i n c r e a s e d e p i t h e l i a l p e r m e a b i l i t y t o g e t h e r w i t h l a r g e numbers o f PMN's i n the a i rway l umena , p r o v i d e d a d d i t i o n a l s u p p o r t f o r the h y p o t h e s i s t h a t i n f l a m m a t i o n may be the c r u c i a l e a r l y e ven t i n the p a t h o g e n e s i s o f o b s t r u c t i v e a i rways d i s e a s e . T h i s i n c r e a s e i n p e r m e a b i l i t y was a l s o shown t o o c c u r i n human smokers (70) and t o be r e v e r s i b l e upon c e s s a t i o n o f smoking ( 7 1 ) . T h i s r a i s e d the p o s s i b i l i t y t h a t the i n i t i a l i n f l a m m a t o r y r e s p o n s e need no t be a s s o c i a t e d w i t h i r r e v e r s i b l e damage. T h e r e f o r e , i d e n t i f i c a t i o n o f t h o s e p a t i e n t s i n whom e a r l y a i rways i n f l a m m a t i o n i s p r e s e n t may a l l o w i n t e r v e n t i o n o r a t l e a s t r e d u c t i o n o f exposu re t o such an e x t e n t t h a t i r r e v e r s i b l e damage might be p r e v e n t e d . These s t u d i e s a l s o added s u p p o r t to a second h y p o t h e s i s : t h a t i n c r e a s e d e p i t h e l i a l p e r m e a b i l i t y may be r e s p o n s i b l e f o r the h y p e r - s e n s i t i v i t y o f a i rways wh i ch had been r e p o r t e d f o l l o w i n g exposu re t o NO^ and o z o n e , o r f o l l o w i n g a cu t e v i r a l i n f e c t i o n o f t he upper r e s p i r a t o r y t r a c t ( 7 2 , 7 3 ) . I f a s i m i l a r i n f l a m m a t o r y r e s p o n s e o c c u r r e d d u r i n g t hese e ven t s l e a d i n g t o an i n c r e a s e i n e p i t h e l i a l p e r m e a b i l i t y t h i s c o u l d a l l o w g r e a t e r p e n e t r a t i o n o f m e d i a t o r s t o the u n d e r l y i n g i r r i t a n t r e c e p t o r s o r b r o n c h i a l smooth musc l e ( 7 4 ) . These i d e a s and hypo theses were f o l l o w e d up i n the t h r e e s e p a r a t e s e t s o f e x p e r i m e n t s d i s c u s s e d i n t h i s r e p o r t . The f i r s t s e r i e s was d i r e c t e d towards e a r l y i d e n t i f i c a t i o n o f a i rway i n f l a m m a t i o n by r a d i o a c t i v e l a b e l l i n g o f the PMN's f ound w i t h i n the - 58 -airway lumena. The second s e r i e s f o l l o w e d the hypothesis that the increase i n e p i t h e l i a l p e r m e a b i l i t y may r e s u l t from \"unzipping\" of e p i t h e l i a l t i g h t j u n c t i o n s or i n c r e a s i n g e p i t h e l i a l \"pore\" s i z e by some mechanism during the inflammatory response ( e i t h e r to c i g a r e t t e smoke or to antigen challenge) and that t h i s may a l l o w greater p e n e t r a t i o n of the mediators r e s p o n s i b l e f o r airway h y p e r - r e a c t i v i t y . The t h i r d s e r i e s looked at the p o s s i b l e l a t e consequences of t h i s inflammatory response i n persons exposed to the dual onslaught of c i g a r e t t e smoke and o c c u p a t i o n a l dust and fume. Does the increased p e r m e a b i l i t y a l l o w greater dust penetrance and thus greater or a d i f f e r e n t p a t t e r n of airway disease than that seen among smokers not exposed to dust? 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H o i d a l JR, N iewoehner DE: P a t h o g e n e s i s o f emphysema. C h e s t 1983 ; 83 :679-685 - 64 -4 5 . J a n o f f A S c h e r e r J : M e d i a t o r s o f i n f l a m m a t i o n i n l e u k o c y t e l y sosomes IX. E l a s t i n o l y t i c a c t i v i t y i n g r a n u l e s o f human p o l y m o r p h o n u c l e a r l e u k o c y t e s . J Exp Med 1968 ; 128:1137-1155 4 6 . Ca rp H, J a n o f f A : In v i t r o s u p p r e s s i o n o f serum e l a s t a s e - i n h i b i t o r y c a p a c i t y by r e a c t i v e oxygen s p e c i e s g e n e r a t e d by p h a g o c y t o s i n g p o l y m o r p h o n u c l e a r l e u k o c y t e s . J C l i n I n v e s t 1979 ; 63 :793-797 4 7 . J a n o f f A : P r o t e a s e s and l u n g i n j u r y . C h e s t 1983 ; 83 :54S-58S 48 . Gadek J E , F e l l s GA, C r y s t a l RG: C i g a r e t t e smoking i n d u c e s f u n c t i o n a l a n t i p r o t e a s e d e f i c i e n c y i n the l ower r e s p i r a t o r y t r a c t o f humans. S c i e n c e 1979 ; 206:1315-1316 4 9 . Cohen AB , James HL: R e d u c t i o n o f the e l a s t a s e i n h i b i t o r y c a p a c i t y o f a l p h a ^ - a n t i t r y p s i n by p e r o x i d e s i n c i g a r e t t e smoke. Am Rev R e s p i r D i s 1982 ; 126 :25-30 50 . S tone P J , C a l o r e JD , Be rna rdo J , S n i d e r GL , F r a n z b l a u C : F u n c t i o n a l ^ - p r o t e a s e i n h i b i t o r i n the l ower r e s p i r a t o r y t r a c t o f c i g a r e t t e smokers i s no t d e c r e a s e d . S c i e n c e 1983 ; 221:1187-1189 51 . P i c k r e l l JA , G r e g o r y RE , C o l e D J , Hahn F F : E f f e c t o f a cu t e ozone exposu re on the p r o t e i n a s e - a n t i p r o t e i n a s e b a l a n c e i n the r a t l u n g . Am Rev R e s p i r D i s 1983 ; 127 :182 52 . Rennard S, Be rg R, Moss J , S a l t zman L, Horn B, S t i e r L, Gadek J , F e l l s G, C r y s t a l R: P r o t e a s e m e d i a t e d a l t e r a t i o n o f c o l l a g e n p r o d u c t i o n by l u n g f i b r o b l a s t s . Am Rev R e s p i r D i s 1981 ; 123 ( P a r t 2 ) : 2 2 5 - 65 -53 . Keogh BA, C r y s t a l RG: A l v e o l i t i s : the key t o the i n t e r s t i t i a l l u n g d i s o r d e r s . Thorax 1982 ; 37 :1-10 54. S imson FW: R e c o n s t r u c t i o n models showing the m o d e r a t e l y e a r l y s i m p l e s i l i c o t i c p r o c e s s and how i t a f f e c t s d e f i n i t e p a r t s o f the p r i m a r y u n i t o f the l u n g . J Pa th Bac t 1935 ; 40 :37-44 55 . B e g i n R, Masse S, Bureau MA: E x p e r i m e n t a l a s b e s t o s i s i n t he sheep m o d e l : Morpho logy and f u n c t i o n o f the a i rways d u r i n g the i n i t i a l a l v e o l i t i s . Am Rev R e s p i r D i s 1982: 125 :149 56 . W r i gh t J L , Churg A : M o r p h o l o g i c f e a t u r e s o f s m a l l a i rway l e s i o n s i n p a t i e n t s w i t h a s b e s t o s e x p o s u r e . Human P a t h o l 1983: ( i n p r e s s ) 57 . N iewoehner DE , K l e i n e r m a n J , R i c e DB: P a t h o l o g i c changes i n the p e r i p h e r a l a i rways o f young smokers . New E n g l J Med 1974 ; 291:755-758 58 . K i l b u r n KH, McKenz ie WN, T h u r s t o n RJ: C e l l u l a r e f f e c t s o f c i g a r e t t e smoke on hamste r a i r w a y s . C h e s t 1975 ; 67 :54S 59 . H u l b e r t W, Wa lke r DC, J a c k s o n A , Hogg J C : A i rway m u c o s a l p e r m e a b i l i t y t o h o r s e r a d i s h p e r o x i d a s e i n g u i n e a - p i g s : t he r e p a i r phase a f t e r i n j u r y by c i g a r e t t e smoke. Am Rev R e s p i r D i s 1981 ; 123 :320-326 60 . C o s i o MG, Ha l e KA, N iewoehner DE: M o r p h o l o g i c and morphomet r i c e f f e c t s o f p r o l o n g e d c i g a r e t t e smoking on the s m a l l a i r w a y s . Am Rev R e s p i r D i s 1980 ; 122:265-271 6 1 . Boatman ES , Sa to S, F r a n k R: A c u t e e f f e c t s o f ozone on c a t l u n g s . I I S t r u c t u r a l . Am Rev R e s p i r D i s 1974 ; 110 :157-169 - 66 -6 2 . Ba tes DV: The r e s p i r a t o r y b r o n c h i o l e as a t a r g e t o rgan f o r t he e f f e c t s o f d u s t s and g a s e s . J Occup Med 1973 ; 15 :177-180 6 3 . Churg A , W r i gh t J L : S m a l l a i rways l e s i o n s i n p a t i e n t s exposed t o n o n a s b e s t o s m i n e r a l d u s t s . Human P a t h o l 1983 , 14 :688-693 64 . C o s i o M, Ghezzo H, Hogg JD , C o r g i n R, L o v e l a n d M, Dosman J , Macklem PT: The r e l a t i o n s between s t r u c t u r a l changes i n s m a l l a i rways and pu lmonary f u n c t i o n t e s t s . New E n g l J Med 1978 ; 298:1277-1281 6 5 . N iewoehner DE , C o s i o MG: C h r o n i c o b s t r u c t i v e l u n g d i s e a s e : The r o l e o f a i rway d i s e a s e , w i t h s p e c i a l emphas is on the p a t h o l o g y o f s m a l l a i rways I n : T h u r l b e c k WM, A b e l l MR, e d s , The Lung S t r u c t u r e . F u n c t i o n and D i s e a s e . B a l t i m o r e : W i l l i a m s and W i l k i n s , 1978 66 . S imonsson BG: B r o n c h i a l r e a c t i v i t y i n o c c u p a t i o n a l asthma and b r o n c h i t i s . Eur J R e s p i r D i s 1980 ; 6 1 ( S u p p l 107 ) :177-181 6 7 . Nade l JA : Mechanisms o f a i rway h y p e r i r r i t a b i l i t y : r o l e o f e p i t h e l i a l damage. I n : S adou l P, M i l i c - E m i l i J , S imonsson BG, C l a r k T JH , e d s , S m a l l A i rways i n H e a l t h and D i s e a s e Amsterdam: E x c e r p t a M e d i c a , 1979 68 . Laennec RTH: A T r e a t i s e on the D i s e a s e s o f the C h e s t and on M e d i a t e A u s c u l t a t i o n , ( t r a n s l a t e d by John F o r b e s ) New Y o r k : Wood, 1835 6 9 . Boucher RC, Johnson J , Inoue S, H u l b e r t W, Hogg JC : The e f f e c t o f c i g a r e t t e smoke on the p e r m e a b i l i t y o f g u i n e a p i g a i r w a y s . Lab I n v e s t 1980 ; 43 :94-100 - 67 -70. Jones JG , L aw l e r P, C raw ley JCW, M i n t y BD, Hu lands G , V e a l l N: I n c r e a s e d a l v e o l a r e p i t h e l i a l p e r m e a b i l i t y i n c i g a r e t t e smoke r s . L a n c e t 1980 ; 1:66-68 7 1 . M i n t y BD, J o r d a n C , Jones JG : R a p i d improvement i n abnorma l pu lmonary e p i t h e l i a l p e r m e a b i l i t y a f t e r s t o p p i n g c i g a r e t t e s . Br Med J 1981 ; 282:1183-1186 72 . Empey DW, L a i t i n e r L A , J a cobs L, G o l d WM, Nade l JA : Mechanisms o f b o n c h i a l h y p e r r e a c t i v i t y i n norma l s u b j e c t s a f t e r uppe r r e s p i r a t o r y t r a c t i n f e c t i o n . Am Rev R e s p i r D i s 1976 ; 113 :131-139 73 . Dimeo MJ , G l e n n MG, Hotzman MJ , S h e l l e r JR, Nade l JA , Boushey HA: T h r e s h o l d c o n c e n t r a t i o n o f ozone c a u s i n g an i n c r e a s e i n b r o n c h i a l r e a c t i v i t y i n humans and a d a p t a t i o n w i t h r e p e a t e d e x p o s u r e s . Am Rev R e s p i r D i s 1981 ; 124:245-248 74. Hogg J C , Pa re PD, Boucher RC: B r o n c h i a l m u c o s a l p e r m e a b i l i t y . Fed P roc 1979 ; 38 :197-201 - 68 -V . An I n v e s t i g a t i o n o f S m a l l A i rways I n f l a m m a t i o n u s i n g Ga-67 as a Marker o f I n f l ammato ry C e l l s I n t r o d u c t i o n I n f l a m m a t i o n o f p e r i p h e r a l a i rways The c o n c e p t t h a t d i s e a s e o f the s m a l l a i rways i s i m p o r t a n t i n the deve lopment o f a i rway o b s t r u c t i o n was i n t r o d u c e d by Hogg and h i s c o l l e a g u e s i n 1968 ( 1 ) . U s i n g a method f o r the measurement o f a i rway r e s i s t a n c e i n e x p e r i m e n t a l a n i m a l s d e v e l o p e d by Macklem and Mead ( 2 ) , t h e s e i n v e s t i g a t o r s showed t h a t the r e s i s t a n c e o f the p e r i p h e r a l a i rways ( < 2mm i n t e r n a l d i a m e t e r ) i n a norma l human au topsy l u n g s a c c o u n t e d f o r o n l y 25% o f t o t a l a i rway r e s i s t a n c e , bu t t h a t t h i s p r o p o r t i o n r o s e t o 54 t o 93% i n l u n g s w i t h emphysema, b r o n c h i e c t a s i s , o r b r o n c h i o l i t i s . They f ound t h i s o b s t r u c t i o n i n p e r i p h e r a l a i rways due t o i n f l a m m a t i o n , mucous p l u g g i n g o r f i b r o s i s and p r o p o s e d t h a t t h i s \" s m a l l a i rways d i s e a s e \" was c o m p r i s e d o f a r e v e r s i b l e component o f a c u t e i n f l a m m a t i o n and mucous p l u g g i n g wh i ch may l e a d t o i r r e v e r s i b l e n a r r o w i n g due t o f i b r o s i s and consequen t o b l i t e r a t i o n o f the a i r w a y s . E a r l i e r r e p o r t s o f m o r p h o l o g i c a b n o r m a l i t i e s i n s m a l l a i rways ( 3 , 4 , 5 , 6 ) had a l s o i m p l i c a t e d i n f l a m m a t i o n , mucous p l u g g i n g and n a r r o w i n g o r o b l i t e r a t i o n o f b r o n c h i o l e s i n the e a r l y p a t h o g e n e s i s o f emphysema. - 69 -In 1969 , B ignon and co-workers (7) r e p o r t e d a s t udy o f p a t i e n t s d y i n g i n s e v e r e r e s p i r a t o r y f a i l u r e . In the subgroup o f t h e s e p a t i e n t s w i t h m i n i m a l emphysema, they f o u n d h y p e r p l a s t i c b r o n c h i o l a r n a r r o w i n g ; a c u t e , s u b a c u t e , and c h r o n i c i n f l a m m a t i o n ; and f i b r o s i s o f membranous b r o n c h i o l e s . A f u r t h e r r e p o r t o f s m a l l a i rway morpho logy i n seven p a t i e n t s w i t h c h r o n i c a i rways o b s t r u c t i o n on pu lmonary f u n c t i o n t e s t s w i t h o u t c l i n i c a l e v i d e n c e o f emphysema, was p r e s e n t e d by Macklem and c o l l e a g u e s i n 1971 ( 8 ) . I n f l a m m a t i o n o f s m a l l b r o n c h i and b r o n c h i o l e s was common t o a l l c a se s and t h e r e was v a r i a b l e mucous p l u g g i n g , n a r r o w i n g , and p e r i b r o n c h i o l a r f i b r o s i s . A d d i t i o n a l q u a n t i t a t i v e s t u d i e s i n p a t i e n t s w i t h c h r o n i c a i rways o b s t r u c t i o n ( 9 , 1 0 , 1 1 ) c o n f i r m a i rway n a r r o w i n g as c h a r a c t e r i s t i c o f t h i s d i s o r d e r , a l t h o u g h t h i s na r r ow ing was f o u n d t o be r e l a t i v e l y s l i g h t i n one g roup o f emphysematous p a t i e n t s ( 1 1 ) . The f i n d i n g by Hogg and a s s o c i a t e s (1) d e s c r i b e d above i n d i c a t e d t h a t s i g n i f i c a n t d i s e a s e may be p r e s e n t i n p e r i p h e r a l a i rways w i t h o u t any a f f e c t on t o t a l a i r f l o w r e s i s t a n c e . A n t h o n i s e n and c o l l e a g u e s (12) had shown, i n 1967 , t h a t a b n o r m a l i t i e s o f gas d i s t r i b u t i o n and V/Q r a t i o s c o u l d be p r e s e n t i n i n d i v i d u a l s who had norma l r o u t i n e f u n c t i o n t e s t s . C o n s e q u e n t l y , i d e n t i f i c a t i o n o f f u n c t i o n a l a b n o r m a l i t i e s o f p e r i p h e r a l a i rways i n p a t i e n t s w i t h o u t s e v e r e d i s e a s e became the o b j e c t o f a number o f i n v e s t i g a t i o n s and s e v e r a l new pu lmonary f u n c t i o n t e s t s were d e v e l o p e d t o t h i s end (13-16 ) . Young c i g a r e t t e smokers t y p i c a l l y t e n d t o show a b n o r m a l i t i e s i n one o r more o f t h e s e t e s t s w i t h o u t s i g n i f i c a n t change i n FEV , o r - 70 -F E V ^ F V C . P a t h o l o g i c a l a b n o r m a l i t i e s i n t hese p a t i e n t s w i t h o u t s e v e r e o b s t r u c t i o n o r l i m i t a t i o n t o f l o w were i n v e s t i g a t e d by Matsuba and T h u r l b e c k ( 1 7 ) . They s t u d i e d p a t i e n t s w i t h o u t e v i d e n c e o f c h r o n i c a i r f l o w o b s t r u c t i o n o r emphysema but w i t h mucous h y p e r s e c r e t i o n and found an e x c e s s o f v e r y nar row a i rways ( 0 . 2 - 0 . 6 mm i n t e r n a l d i a m e t e r ) bu t no l o s s o f a i rways and a 3 f o l d i n c r e a s e i n mucus. T h i s was f o l l o w e d i n 1974 by N iewoehner and c o l l e a g u e s (18) who compared au topsy l u n g s f rom 20 young smokers w i t h o u t e v i d e n c e o f emphysema who d i e d s u d d e n l y o u t s i d e h o s p i t a l t o 19 s i m i l a r l y chosen non-smokers . The smoke rs ' l u n g s showed a c c u m u l a t i o n s o f p igmented macrophages w i t h i n the lumena o f r e s p i r a t o r y b r o n c h i o l e s and i n c r e a s e s i n m u r a l i n f l a m m a t o r y c e l l s and denuded e p i t h e l i u m i n membranous b r o n c h i o l e s . T h i s l e s i o n has been p o s t u l a t e d as a p r e c u r s o r o f c e n t r i l o b u l a r emphysema ( 1 9 ) . In 1978 , C o s i o and co-workers (20) p r o v i d e d e v i d e n c e t h a t p a t h o l o g i c a l a b n o r m a l i t i e s i n p e r i p h e r a l a i rways c o r r e l a t e d w i t h a b n o r m a l i t i e s i n t h o s e f u n c t i o n t e s t s d e s i g n e d t o i n v e s t i g a t e t h e s e a i r w a y s . The a i rways f r om l o b e s o r l u n g s removed s u r g i c a l l y were g r a d e d u s i n g a sys tem s i m i l a r t o t h a t o f N iewoehner (18) bu t t a k i n g i n t o a c c o u n t deg rees o f s e v e r i t y o f the v a r i a b l e s g r a d e d . The p a t h o l o g y v a r i a b l e s a s s e s s e d were deg ree o f o c c l u s i o n by mucus and c e l l s ( c o r r e c t e d f o r l u n g i n f l a t i o n ) , p r e s e n c e o r absence o f m u c o s a l u l c e r s , and the p r e s e n c e and s e v e r i t y o f g o b l e t and squamous c e l l m e t a p l a s i a , i n f l a m m a t o r y c e l l i n f i l t r a t i o n , c o n n e c t i v e t i s s u e - 71 -d e p o s i t i o n , smooth musc l e h y p e r p l a s i a , and d e p o s i t i o n o f p igment i n t he w a l l o f membranous a i rways l e s s than 2 mm i n t e r n a l d i a m e t e r . The t o t a l s c o r e f o r each p a t i e n t was used t o d i v i d e the whole g roup i n t o f o u r subgroups w i t h i n c r e a s i n g s m a l l a i rway p a t h o l o g y . The g roup w i t h the l e a s t p a t h o l o g y had no s i g n i f i c a n t l y abnormal f u n c t i o n t e s t s whereas i n c r e a s i n g p a t h o l o g y c o r r e l a t e d w i t h abnormal t e s t s o f c l o s i n g c a p a c i t y , s l o p e o f phase I I I o f the washout c u r v e , and volume o f i s o f l o w u s i n g h e l i u m and a i r . The s p e c i f i c p a t h o l o g y v a r i a b l e s wh i ch c o r r e l a t e d were i n f l a m m a t o r y i n f i l t r a t i o n , f i b r o s i s , and squamous m e t a p l a s i a . They c o n c l u d e d t h a t the p r i m a r y l e s i o n i n t h e s e p a t i e n t s was an i n f l a m m a t o r y one t h a t c o u l d be d e t e c t e d a t a t ime when t h i s l e s i o n was s t i l l p o t e n t i a l l y r e v e r s i b l e . Be rend and c o l l e a g u e s (21 ,22 ) and P e t t y and c o l l e a g u e s (23) have p r o v i d e d a d d i t i o n a l e v i d e n c e t h a t the s p e c i a l i z e d t e s t s o f s m a l l a i rways f u n c t i o n c o r r e s p o n d t o p a t h o l o g i c a l a b n o r m a l i t i e s o f p e r i p h e r a l a i r w a y s . However , Be rend and co-workers (21 ,22 ) a l s o p o i n t ou t t h a t i n f l a m m a t i o n a l o n e does not appear t o r e s u l t i n a s i g n i f i c a n t r e d u c t i o n i n s m a l l a i rway d i m e n s i o n s . L o o k i n g a t b o t h membranous and r e s p i r a t o r y b r o n c h i o l e s W r i gh t and a s s o c i a t e s (24) f o u n d t h a t i n s u b j e c t s w i t h F E V ^ ^ 80% p r e d i c t e d , r e s p i r a t o r y b r o n c h i o l e s showed o n l y a b n o r m a l i t i e s o f i n f l a m m a t i o n , and t h a t i n f l a m m a t i o n and f i b r o s i s combined c o r r e l a t e d w i t h i n c r e a s i n g numbers o f abnormal s m a l l a i rway f u n c t i o n t e s t s . T h i s i n f l a m m a t i o n was p r e s e n t bo th w i t h i n the lumen and the a i rway w a l l . The s p e c i f i c e f f e c t s o f c i g a r e t t e smoke i n p e r i p h e r a l a i rways - 72 -were r e c e n t l y i n v e s t i g a t e d by C o s i o and a s s o c i a t e s ( 2 5 ) . T h e i r p a t i e n t s were 25 smokers and 14 l i f e t i m e non-smokers a l l o v e r age 40 (w i t h the non-smokers b e i n g somewhat o l d e r than the s m o k e r s ) . A g a i n , the smokers showed i n c r e a s e d i n f l a m m a t i o n i n membranous and r e s p i r a t o r y b r o n c h i o l e s as w e l l as g o b l e t c e l l m e t a p l a s i a , i n c r e a s e d smooth m u s c l e , and an i n c r e a s e i n the number o f a i rways l e s s than 400/1 i n t e r n a l d i a m e t e r . I n t e r e s t i n g l y , t hey f ound c o n s i d e r a b l e o v e r l a p between smokers and non-smokers , i n d i c a t i n g o t h e r f a c t o r s must a l s o be i m p l i c a t e d i n the c r e a t i o n o f t h e s e l e s i o n s . S i m i l a r l y , W r i gh t and c o l l e a g u e s (26) compared c u r r e n t smokers to ex-smokers and non-smokers , f i n d i n g the smokers t o have i n c r e a s e d i n f l a m m a t i o n i n r e s p i r a t o r y b r o n c h i o l a r w a l l s and lumena as w e l l as f i b r o u s t i s s u e and p igment w h i l e the membranous b r o n c h i o l e s showed g o b l e t c e l l m e t a p l a s i a . A n i m a l mode ls o f a i rway i n f l a m m a t i o n The i n v e s t i g a t i o n s o f s u r g i c a l o r au topsy spec imens d i s c u s s e d above , appea red t o c o n f i r m t h a t c i g a r e t t e smoke exposu re r e s u l t s i n i t i a l l y i n an i n f l a m m a t o r y l e s i o n o f the p e r i p h e r a l a i r w a y s , t h a t , i n i t s e a r l y s t a g e s , i s p o t e n t i a l l y r e v e r s i b l e . E x p e r i m e n t a l e v i d e n c e f r om a n i m a l i n v e s t i g a t i o n s p r o v i d e s f u r t h e r c o n f i r m a t i o n o f t h i s r e l a t i o n s h i p , and i n d i c a t e s t h a t exposu re t o o t h e r i n h a l e d e n v i r o n m e n t a l agen ts may p rovoke a s i m i l a r r e s p o n s e . Asmundsson and co-workers (27) exposed hamste rs t o a modera te l e v e l o f SO . gas p l u s c a r b o n d u s t and f o u n d n e u t r o p h i l r e c r u i t m e n t - 73 -i n t o the a i rway e p i t h e l i u m and lumen 24 hours a f t e r e x p o s u r e . T h i s PMN r e c r u i t m e n t was a l s o seen w i t h h i g h SO^ l e v e l s bu t not when the modera te exposu re was g i v e n w i t h o u t c a r b o n d u s t . S i m i l a r s t u d i e s f r o m t h i s same l a b o r a t o r y u s i n g exposu re t o c o t t o n d u s t and e x t r a c t s (28) a l s o i n d i c a t e d PMN r e c r u i t m e n t t h rough a i rway w a l l s , a l t h o u g h i n t h i s c a s e , the peak r e s p o n s e o c c u r r e d 4-6 hours a f t e r e x p o s u r e . These a u t h o r s a t t r i b u t e d the t ime d i f f e r e n c e t o a more d i r e c t mechanism o f r e c r u i t i n g l e u k o c y t e s by the c o t t o n e x t r a c t s wh ich a re s o l u b l e i n n o n - p o l a r s o l v e n t s and thus may r e a c t d i r e c t l y w i t h e p i t h e l i a l c e l l membranes. C i g a r e t t e smoke exposu re i n t h i s same hamster mode l p r o d u c e d s i m i l a r r e s u l t s (29) w i t h PMN r e c r u i t m e n t a t a l l l e v e l s i n t he t r a c h e o b r o n c h i a l t r e e . H u l b e r t and a s s o c i a t e s (30) exposed g u i n e a p i g s t o c i g a r e t t e smoke and found peak PMN r e c r u i t m e n t s i x hou r s a f t e r e x p o s u r e . In a l l t h e s e s t u d i e s the a u t h o r s n o t e d t h a t the r e c r u i t e d l e u k o c y t e s c o u l d be f o u n d i n s u b e p i t h e l i a l , e p i t h e l i a l , and l u m e n a l l o c a t i o n s . In the g u i n e a p i g model (30) the l umena l component was p a r t i c u l a r l y l a r g e w i t h e v i d e n c e o f mass i v e numbers o f PMN's p r e s e n t w i t h i n the mucous l a y e r . T h i s f i n d i n g l e d t o the i d e a t h a t a e r o s o l a d m i n i s t r a t i o n o f a t r a c e r wh i ch m igh t b i n d t o PMN's may w e l l be u s e f u l as an i n d i c a t o r o f t h i s e a r l y a i rway i n f l a m m a t i o n . To t h i s e n d , i t was p r o p o s e d t o s t u d y the r a d i o i s o t o p e G a l l i u m -67 t o d e t e r m i n e i t s u s e f u l n e s s , i n a e r o s o l e x p o s u r e , as a marker o f i n f l a m m a t i o n . - 74 -Use o f R a d i o g a l l i u m - H i s t o r i c a l P e r s p e c t i v e R a d i o g a l l i u m has been used i n n u c l e a r m e d i c i n e s i n c e the l a t e 1 9 4 0 ' s when i t was o b s e r v e d t h a t g a l l i u m t ended t o l o c a l i z e i n a c t i v e o s t e o g e n i c s i t e s i n the body ( 3 1 ) . S e v e r a l u n p r o d u c t i v e t r i a l s were made w i t h Ga-72 t o i n v e s t i g a t e and t r e a t m a l i g n a n c i e s i n bone . The n e g a t i v e r e s u l t s were i n p a r t due t o the u n f a v o u r a b l e decay c h a r a c t e r i s t i c s o f t h i s i s o t o p e so i n v e s t i g a t i o n s s t a r t e d u s i n g Ga-67 wh i ch had a l o n g e r h a l f l i f e (78 hou r s ) and l e s s p e n e t r a t i n g gamma r a d i a t i o n ( 3 1 ) . I t was i n the c o u r s e o f t h e s e s t u d i e s i n the ' 5 0 ' s t h a t s i g n i f i c a n t d i f f e r e n c e s i n d i s t r i b u t i o n and e x c r e t i o n p a t t e r n s were f o u n d when u s i n g c a r r i e r - f r e e g a l l i u m v e r s e s g a l l i u m w i t h added s t a b l e g a l l i u m . The c a r r i e r - f r e e g a l l i u m - 6 7 shows a d e c r e a s e d r a t e o f up take and deg ree o f d e p o s i t i o n i n bone , i n c r e a s e d l o c a l i z a t i o n i n l i v e r and o t h e r s o f t t i s s u e , s l owe r b l o o d c l e a r a n c e , and a r e v e r s a l o f the p r e v i o u s l y o b s e r v e d f e c a l / u r i n a r y e x c r e t i o n p a t t e r n such t h a t more than 12% o f c a r r i e r - f r e e g a l l i u m - 6 7 - c i t r a t e i s e x c r e t e d by the k i d n e y i n the f i r s t 24 hours a f t e r wh i ch the l i v e r becomes the major r o u t e ( 3 2 ) . I t was no t u n t i l the l a t e 1 9 6 0 ' s however , t h a t i t was o b s e r v e d t h a t t h e r e was i n t e n s e l o c a l i z a t i o n o f g a l l i u m - 6 7 i n t he lymph nodes o f p a t i e n t s w i t h H o d g k i n ' s d i s e a s e ( 3 1 ) . A t a p p r o x i m a t e l y the same t ime i t was n o t e d t h a t g a l l i u m - 6 7 d e p o s i t i o n was i n c r e a s e d i n a r ea s o f i n f l a m m a t i o n and i n f a c t t h e r e was c o n c e r n t h a t i t s tumor l o c a l i z i n g p r o p e r t i e s were r e a l l y r e l a t e d t o the i n f l ammato r y - 75 -r e a c t i o n . T h i s i s now g e n e r a l l y b e l i e v e d no t to be the c a se and i t i s w i d e l y a c c e p t e d t h a t g a l l i u m - 6 7 c o n c e n t r a t e s i n bo th m a l i g n a n t t i s s u e and i n i n f l a m m a t o r y t i s s u e . L o c a l i z a t i o n o f G a l l i u m - 6 7 The mechanism o f l o c a l i z a t i o n o f g a l l i u m - 6 7 i n i n f l a m m a t o r y l e s i o n s has been i n v e s t i g a t e d i n the p a s t d e c a d e . G e l r u d and a s s o c i a t e s (33) showed t h a t the r a d i o i s o t o p e b i n d s t o t he p o l y m o r p h o n u c l e a r l e u k o c y t e i n a r eas o f i n f l a m m a t i o n ; and Swa r t zend rube r and c o l l e a g u e s ( 3 4 ) , u s i n g l i g h t and e l e c t r o n m i c r o s c o p i c a u t o - r a d i o g r a p h y showed g a l l i u m - 6 7 t o be a s s o c i a t e d w i t h l y sosomes o r r e l a t e d p a r t i c l e s i n l i v e r , thymus, s p l e e n , and lymph nodes o f b o t h l e u k e m i c and non- leukemic m i c e . However , i n v i t r o s t u d i e s by Tsan and co-workers (35) d e m o n s t r a t e d t h a t a t l e a s t 50% o f the g a l l i u m t aken up by PMN's i s bound t o the p l asma membrane wh i ch s e r v e s as a d i f f u s i o n b a r r i e r i n no rma l c e l l s . However h e a t - k i l l e d PMN's show s i g n i f i c a n t i n c r e a s e s i n up take o f g a l l i u m - 6 7 . A d d i t i o n a l s t u d i e s by t hese same worke r s (35) i n d i c a t e d t h a t 80% o f g a l l i u m - 6 7 was f ound i n the s o l u b l e , n o n - c e l l u l a r f r a c t i o n . As w e l l , two c a se s r e p o r t e d by Dhawan and co-workers (36) have shown a c c u m u l a t i o n o f g a l l i u m i n i n f l a m m a t o r y s i t e s i n the absence o f c i r c u l a t i n g PMN 's . The a u t h o r s s u g g e s t e d t h a t l ymphocy t e s may have c o n t r i b u t e d t o the a c c u m u l a t i o n o r t h a t a n o n - c e l l u l a r - 76 -pathway was r e s p o n s i b l e . ( G a l l i u m has been shown t o b i n d t o t r a n s f e r r i n i n p l a sma and t o t i s s u e l a c t o f e r r i n ( 3 6 , 3 7 ) ) . These f i n d i n g l e a d Tsan and S c h e f f e l (38) t o h y p o t h e s i z e i n 1979 t h a t g a l l i u m - 6 7 a c c u m u l a t e d i n i n f l a m m a t o r y l e s i o n s m a i n l y due t o l e a k a g e o f t r a n s f e r r i n bound g a l l i u m t h r o u g h the more permeab le c a p i l l a r i e s i n t o the i n t e r s t i t i u m where i t c o u l d be bound by n o n - v i a b l e PMN's w i t h a l e s s e r amount a t t a c h e d t o the v i a b l e PMN 's . I n v e s t i g a t i o n by We iner and a s s o c i a t e s (39) i d e n t i f i e d PMN l a c t o f e r r i n as the major b i n d i n g p r o t e i n p r e s e n t i n t h e s e c e l l s , a l t h o u g h b i n d i n g t o t h i s m o l e c u l e o n l y a c c o u n t e d f o r 36% o f the t o t a l a c t i v i t y a b s o r b e d by PMN 's . A s e r i e s o f e x p e r i m e n t s c a r r i e d ou t by Hayes and h i s c o l l e a g u e s ( 4 0 , 4 1 , 4 2 ) p r o v i d e d a d d i t i o n a l i n f o r m a t i o n r e g a r d i n g the mechanism o f up take o f g a l l i u m , and l e a d t o a new h y p o t h e s i s as t o the mechan ism. They p r o p o s e d t h a t g a l l i u m i s p r e s e n t i n the p l asma i n two compar tments : f r e e Ga-67 , wh i ch r o u t e s t o b o n e , e x c r e t a and tumor ; and p r o t e i n - b o u n d Ga-67 wh i ch r o u t e s t o norma l s o f t t i s s u e and i n f l a m m a t o r y l e s i o n s . Suppo r t f o r t h i s h y p o t h e s i s was f o u n d i n t h e i r e x p e r i m e n t s i n wh i ch the b i n d i n g o f g a l l i u m t o p l asma p r o t e i n s was m a n i p u l a t e d by v a r i o u s a g e n t s . They f u r t h e r h y p o t h e s i z e d t h a t e n d o c y t o s i s may be r e p o n s i b l e f o r the up take o f g a l l i u m i n i n f l a m m a t o r y l e s i o n s . G a l l i u m A c c u m u l a t i o n i n Lung D i s e a s e C l i n i c a l use o f i n j e c t e d g a l l i u m - 6 7 has shown t h a t - 77 -i n f l a m m a t o r y l e s i o n s can be v i s u a l i z e d by s c i n t i l l a t i o n s c a n n i n g ( 3 1 , 3 3 , 4 2 ) and t h a t i n some c a s e s , the v i s u a l i z a t i o n c o r r e l a t e s w i t h the a c t i v i t y o f the i n f l a m m a t o r y p r o c e s s and the r e s p o n s e t o t h e r a p y ( 3 3 , 4 3 , 4 4 ) . F a l s e n e g a t i v e s and f a l s e p o s i t i v e s do o c c u r but w i t h a low f r e q u e n c y ( 4 3 , 4 4 , 4 5 ) . The use o f g a l l i u m - 6 7 i n the i n v e s t i g a t i o n o f l u n g d i s o r d e r s has been shown t o be o f p a r t i c u l a r v a l u e i n s e l e c t e d p a t i e n t s t o a i d i n p r e o p e r a t i v e e v a l u a t i o n o f pu lmonary n e o p l a s m , e v a l u a t i o n o f pu lmonary i n f i l t r a t e s , assessment o f the i n f l a m m a t o r y a c t i v i t y i n i n t e r s t i t i a l f i b r o s i s , d e t e c t i o n o f c e r t a i n d i f f u s e n e o p l a s t i c and i n f l a m m a t o r y p r o c e s s e s b e f o r e r a d i o g r a p h y i s a b n o r m a l , d e t e c t i o n and e v a l u a t i o n o f p n e u m o c o n i o s i s , and f o r f o l l o w i n g t r e a tmen t i n s a r c o i d o s i s and t u b e r c u l o s i s ( 3 1 , 3 3 - 3 8 , 4 4 , 4 6 - 5 6 ) . Whereas a c c u m u l a t i o n o f g a l l i u m - 6 7 i n norma l l u n g s a f t e r IV a d m i n i s t r a t i o n i s u s u a l l y l ow , t h e r e i s s u b s t a n t i a l a c c u m u l a t i o n i n l u n g s w i t h f o c a l o r d i f f u s e i n f l a m m a t o r y o r n e o p l a s t i c d i s e a s e , and the a c c u m u l a t i o n has been d e m o n s t r a t e d , i n some c a s e s , t o i n d i c a t e more e x t e n s i v e d i s e a e s than i s appa ren t on the c h e s t r a d i o g r a p h ( 4 7 - 5 1 , 5 6 ) , a l t h o u g h a no rma l c h e s t x- ray i s g e n e r a l l y a s s o c i a t e d w i t h a norma l g a l l i u m s c a n . S t u d i e s wh i ch have l o o k e d a t the r e l a t i o n s h i p between the c e l l u l a r i t y o f b r o n c h o - a l v e o l a r l a v a g e and g a l l i u m scans have f o u n d a p o s i t i v e c o r r e l a t i o n between the amount o f the g a l l i u m c o n c e n t r a t i o n and the % n e u t r o p h i l and % l ymphocy tes ( p a r t i c u l a r l y T - l y m p h o c y t e s ) bu t c o n f l i c t i n g e v i d e n c e f o r c o r r e l a t i o n w i t h macrophages ( 44 , 5 3 , 5 4 , 57 , 5 8 ) . A r e c e n t a b s t r a c t by Hunninghake and a s s o c i a t e s (58) - 78 -r e p o r t e d t h a t a l v e o l a r macrophages and n e u t r o p h i l s f rom norma l i n d i v i d u a l s i n c r e a s e d t h e i r i n v i t r o up take o f g a l l i u m when s t i m u l a t e d by p h a g o c y t o s i s o r exposu re t o c h e m o t a c t i c f a c t o r s . In g e n e r a l , the common f e a t u r e o f pu lmonary d i s e a s e s i n wh i ch g a l l i u m - 6 7 a c c u m u l a t i o n i s seen i s the p r e s e n c e o f an a c t i v e p r o c e s s o f c e l l u l a r p r o l i f e r a t i o n ; i n c o n t r a s t , s c a r r e d and f i b r o t i c p r o c e s s e s do no t c o n c e n t r a t e g a l l i u m . A l l s t u d i e s o f l u n g d i s e a s e t o d a t e have been done u s i n g i n j e c t i o n o f g a l l i u m - 6 7 - c i t r a t e . U s i n g t h i s method , s cans done on p a t i e n t s w i t h c h r o n i c o b s t r u c t i v e a i rways d i s e a s e a re g e n e r a l l y n e g a t i v e ( 4 6 ) . T h i s i s no t s u r p r i s i n g g i v e n the s m a l l r e l a t i v e mass o f the a i rways compared t o the whole l u n g and the f a c t t h a t t hey a r e p e r f u s e d v i a the b r o n c h i a l c i r c u l a t i o n , wh i ch n o r m a l l y a c c o u n t s f o r 1% o f the t o t a l c a r d i a c o u t p u t ( 5 9 ) . A e r o s o l a d m i n i s t r a t i o n o f t h i s i s o t o p e , however , may overcome t h e s e p rob lems and a l l o w s e l e c t i v e l a b e l l i n g o f a i rway i n f l a m m a t o r y c e l l s . The f o l l o w i n g e x p e r i m e n t s were d e s i g n e d t o t e s t the h y p o t h e s i s t h a t the a cu t e a i rway i n f l a m m a t i o n w i t h PMN e x u d a t i o n i n t o a i rway lumena seen f o l l o w i n g c i g a r e t t e smoke exposu re may be i d e n t i f i e d by the enhanced up take o f Ga-67 a d m i n i s t e r e d v i a a e r o s o l . - 79 -M e t h o d s : 1. Ga-67 r e t e n t i o n i n g u i n e a p i g s exposed t o c i g a r e t t e smoke Ten S t r a i n 13 g u i n e a p i g s (mean we igh t 436 t 36 g) were s t u d i e d . The a n i m a l s were r a i s e d i n a c o n t a m i n a t i o n - c o n t r o l l e d env i ronment w i t h f o r c e d a i r f l o w and w i r e mesh bottommed cages o v e r r o c k s a l t i n o r d e r t o r educe the i n c i d e n c e o f r e s p i r a t o r y i n f e c t i o n s . F i v e an ima l s were exposed t o 200 p u f f s o f whole c i g a r e t t e smoke o v e r a one hour p e r i o d i n the awake, r e s t r a i n e d s t a t e u s i n g the method d e s c r i b e d by S iman i and a s s o c i a t e s ( 6 0 ) . F i v e c o n t r o l g u i n e a p i g s were exposed t o sham smoking by b e i n g h e l d i n the smoking a p p a r a t u s but exposed t o room a i r . Twelve hours a f t e r the b e g i n n i n g o f t he smoke o r sham e x p o s u r e , each an ima l was exposed t o an a e r o s o l o f Ga-67 c i t r a t e (500 u C i i n 10 ml s a l i n e ) g e n e r a t e d by a d i s p o s a b l e Hudson n e b u l i z e r . The a e r o s o l was g e n e r a t e d i n t o an e n c l o s e d chamber wh i ch s u r r o u n d e d the head o f the a n i m a l . Exposu re was c o n t i n u e d f o r 15 m i n u t e s a t an a i r f l o w r a t e o f 8 1/min. The n e b u l i z e r was we ighed b e f o r e and a f t e r a e r o s o l i z a t i o n and an a l i q u o t o f the n e b u l a n t was c o u n t e d f o r g a l l i u m a c t i v i t y i n a Beckman Gamma 7000 w e l l s c i n t i l l a t i o n c o u n t e r and under a S iemens PHO/gamma s c i n t i l l a t i o n camera . From t h i s , c a l c u l a t i o n s were made o f the g a l l i u m a c t i v i t y n e b u l i z e d as seen by b o t h the camera and the c o u n t e r and l u n g a c t i v i t i e s were e x p r e s s e d i n r e l a t i o n t o t h e s e c a l c u l a t e d amounts n e b u l i z e d . - 80 -F o l l o w i n g g a l l i u m exposu re the an ima l s were c a r e f u l l y and t h o r o u g h l y washed t o remove any r a d i o a c t i v i t y on the f u r o r s k i n , t h e n a n a e s t h e t i z e d w i t h sod ium p e n t o b a r b i t o l (25 mg/kg IP) and p l a c e d p rone o v e r the gamma camera wh i ch was c o n n e c t e d t o a PDP/11 compute r . Counts were o b t a i n e d f rom an a r e a o f i n t e r e s t c o r r e s p o n d i n g ' t o t h e c h e s t o f the a n i m a l . T h i s i m a g i n i n g t ook p l a c e a p p r o x i m a t e l y 1.5 hours a f t e r the s t a r t o f the a e r o s o l e x p o s u r e . Twen t y- fou r hours a f t e r the b e g i n n i n g o f c i g a r e t t e - s m o k e o r sham exposu re (12 h r p o s t g a l l i u m a e r o s o l ) the an ima l s were a g a i n a n e s t h e t i z e d , the c h e s t was opened and two 1 ml b l o o d samples t aken f r om the h e a r t . These were c o u n t e d f o r g a l l i u m - 6 7 a c t i v i t y . The l u n g t i s s u e was f i x e d i n s i t u as f o l l o w s : t he h e a r t and l u n g s were exposed w i t h m i n i m a l d i s r u p t i o n o f the s u r r o u n d i n g v a s c u l a t u r e . An 18 guage n e e d l e was i n s e r t e d i n t o the r i g h t v e n t r i c l e and advanced toward the o u t l e t o f the pu lmonary a r t e r y . The i n f e r i o r vena c a va was c u t , then twenty m i l l i l i t r e s o f no rma l h e p a r i n i z e d s a l i n e were i n f u s e d t o c l e a r the pu lmonary v a s c u l a t u r e . T h i s was f o l l o w e d by i n f u s i o n o f 30 m l . o f 4% g l u t a r a l d e h y d e i n phospha te b u f f e r . Immed ia te l y f o l l o w i n g t h i s , the l u n g s were i n f l a t e d v i a the t r a c h e a , the t r a c h e a c l a m p e d , then the l u n g s removed i n one p i e c e and immersed f o r 2 hours i n 4% g l u t a r a l d e h y d e and h e l d a t 4 ° C . Each l u n g was d i v i d e d i n t o s i x r o u g h l y e q u a l s e c t i o n s , then each was we ighed and c o u n t e d f o r g a l l i u m a c t i v i t y . E i t h e r o f the r i g h t o r l e f t l u n g ( a s s i g n e d randomly ) was d r i e d f o r we t /d ry we igh t a n a l y s i s and the o t h e r l u n g p r o c e s s e d f o r l i g h t m i c r o s c o p y u s i n g m e t h y l m e t h a c r y l a t e r e s i n f o r embedd ing . - 81 -S e c t i o n s (3 .5 u t h i c k ) were t aken f r om each o f the s i x l u n g segments and s t a i n e d w i t h o r t h o - t o l u i d i n e . Each a i rway was a s s e s s e d f o r the deg ree o f i n f l a m m a t o r y i n f i l t r a t e i n b o t h w a l l and lumen and a s s i g n e d a g rade f rom 0 t o 3 i n d i c a t i n g the p r e s e n c e and s e v e r i t y o f t he i n f i l t r a t e . Two c o m p o s i t e s c o r e s were c a l c u l a t e d f o r each t i s s u e s e c t i o n , one f o r c a r t i l a g e o u s a i rways and one f o r n o n - c a r t i l a g e n o u s a i r w a y s , by summing the i n d i v i d u a l a i rway s c o r e s and e x p r e s s i n g the t o t a l as a p r o p o r t i o n o f the maximum p o s s i b l e s c o r e . T o t a l s c o r e s f o r each an ima l were a l s o c a l c u l a t e d i n the same f a s h i o n . G a l l i u m a c t i v i t y i n the l u n g s when removed f rom the a n i m a l was c o r r e c t e d f o r backg round and r a d i o a c t i v e decay and e x p r e s s e d p e r gram d r y we igh t o f l u n g . G a l l i u m r e t e n t i o n i n the l u n g s as c o u n t e d by the gamma camera (1 .5 h r s p o s t exposu re ) and by the w e l l c o u n t e r (12 h r s p o s t exposu re ) was compared f o r smokers and non-smokers u s i n g S t u d e n t ' s u n p a i r e d t - t e s t . S i m i l a r l y , a i rway i n f l a m m a t i o n s c o r e s f o r c a r t i l a g e n o u s and n o n - c a r t i l a g e n o u s a i rways were compared f o r the two g roups u s i n g the s c o r e s f o r each t i s s u e s e c t i o n . C o r r e l a t i o n between the g a l l i u m a c t i v i t y r e t a i n e d and the t o t a l a i rway i n f l a m m a t o r y s c o r e s ( f o r c a r t i l a g e n o u s and n o n - c a r t i l a g e n o u s a i rways s e p a r a t e l y and combined) were d e t e r m i n e d by l i n e a r r e g r e s s i o n a n a l y s i s . 2. Ga-67 r e t e n t i o n i n human s u b j e c t s N ine smokers and e i g h t non-smokers b r e a t h e d an a e r o s o l o f g a l l i u m - 6 7 g e n e r a t e d u s i n g a D e V i l b i s s 2.101 u l t r a s o n i c n e b u l i z e r - 82 -c o n t a i n i n g 2.5 mCi o f G a - c i t r a t e i n 10 m l . s a l i n e . T h i s n e b u l i z e r has a maximum o u t p u t o f 3 ml/min and g e n e r a t e s d r o p l e t s w i t h a mass mean aerodynamic d i a m e t e r o f 6 .3 m i c r o n s ( 6 1 ) . S u b j e c t s i n h a l e d f r o m a mou thp i ece w i t h nose c l i p s i n p l a c e , u s i n g t i d a l b r e a t h i n g . The exposu re l a s t e d 2 m i n u t e s . Immed ia te l y f o l l o w i n g i n h a l a t i o n , s u b j e c t s were p o s i t i o n e d s u p i n e under the gamma camera . Counts were t aken ove r a r e g i o n o f i n t e r e s t c o r r e s p o n d i n g t o the l u n g s , e x c l u d i n g the stomach and the o r o p h a r y n x , t o o b t a i n an assessment o f the dose r e c e i v e d by the l u n g s . Repeat c o u n t s were o b t a i n e d i n a s i m i l a r f a s h i o n a t 24 and 96 hours a f t e r Ga-67 e x p o s u r e . Venous b l o o d samples were t aken a t 15 m inu te i n t e r v a l s o v e r the f i r s t hour and then a g a i n a t 24 and 96 hours i n s e v e r a l s u b j e c t s . G a l l i u m a c t i v i t y r e c o r d e d ove r the l u n g s was c o r r e c t e d f o r backg round and r a d i o a c t i v e decay and the 24 and 96 h r r e a d i n g s were e x p r e s s e d as a p e r c e n t a g e o f the i n i t i a l r e a d i n g . 3. Ga-67 a u t o r a d i o g r a p h y i n g u i n e a p i g s and man S i x g u i n e a p i g s were exposed t o c i g a r e t t e smoke as d e s c r i b e d above and t h r e e were s u b s e q u e n t l y exposed t o the g a l l i u m a e r o s o l . The r e m a i n i n g t h r e e s e r v e d as c o n t r o l s f o r backg round r a d i o a c t i v i t y . T i s s u e f i x a t i o n was c a r r i e d o u t , as i n the f i r s t s e r i e s , w i t h i n one hour a f t e r g a l l i u m exposu re i n two p a i r s o f a n i m a l s . In the t h i r d p a i r (one exposed t o g a l l i u m , one c o n t r o l ) t i s s u e f i x a t i o n was done 23 - 83 -hou r s p o s t g a l l i u m e x p o u r e . The l u n g s were d i v i d e d s a g i t a l l y i n t o t h r e e segments and l u n g s and t r a c h e a c o u n t e d f o r 6 7 G a a c t i v i t y b e f o r e and a f t e r d e h y d r a t i o n f o r embedding p u r p o s e s . S e c t i o n s were t aken f rom each l u n g a r e a ( i n n e r , m i d d l e and o u t e r s l i c e ) and f rom the t r a c h e a , embedded i n m e t h y l m e t h a c r y l a t e r e s i n and c u t 3 . 5 , 5 and 7.5 m i c r o n s t h i c k . The s l i d e s were d i p p e d i n Kodak NTB 2 n u c l e a r - t y p e e m u l s i o n , and d e v e l o p e d a f t e r one and two weeks . One c o n t r o l and one g a l l i u m exposed a n i m a l were p r o c e s s e d on each o c c a s i o n and a d d i t i o n a l b l a n k s l i d e s were a l s o p r o c e s s e d as backg round c o n t r o l s . One human s u b j e c t (age 6 6 , smoking h i s t o r y : 2000 c i g a r e t t e y e a r s ) about t o undergo l u n g r e s e c t i o n f o r a p e r i p h e r a l c o i n l e s i o n , was exposed t o g a l l i u m - 6 7 a e r o s o l as d e s c r i b e d i n s e r i e s 2. Two t i s s u e b l o c k s were t aken randomly f rom the r e s e c t e d spec imen a f t e r f o r m a l i n i n f l a t i o n and f i x a t i o n (24 hours a f t e r g a l l i u m i n h a l a t i o n ) , and p r o c e s s e d f o r a u t o r a d i o g r a p h y as d e s c r i b e d above . A l l e x p e r i m e n t a l p r o c e d u r e s u s i n g human s u b j e c t s were app roved by the human e x p e r i m e n t a t i o n commit tee a t S t . P a u l ' s H o s p i t a l and i n f o r m e d , w r i t t e n c o n s e n t was o b t a i n e d f r om a l l s u b j e c t s . - 84 -R e s u l t s 1. Ga-67 r e t e n t i o n i n g u i n e a p i g s exposed t o c i g a r e t t e smoke G a l l i u m a c t i v i t y r e t a i n e d i n the l u n g s o f the smoke-exposed and c o n t r o l an ima l s as measured by the gamma camera a t 1.5 h r . p o s t exposu re and by w e l l c o u n t i n g 12 h r s p o s t exposu re ( e x p r e s s e d as a f r a c t i o n o f the a c t i v i t y n e b u l i z e d ) i s shown i n F i g u r e 1 (p 1 0 3 ) . The smoke-exposed a n i m a l s r e t a i n e d s i g n i f i c a n t l y more o f the i s o t o p e a t b o t h t ime p e r i o d s ( P < .01 a t 1.5 h r s and p < .02 a t 12 h r s ) . However the r a t i o o f the a c t i v i t y i n c o n t r o l t o t h a t i n smoke-exposed a n i m a l s i s the same a t 12 hours (mean a c t i v i t y i n c o n t r o l s / m e a n a c t i v i t y i n smoke-exposed = .38) as a t 1.5 hours ( . 3 3 ) . Tha t i s , t h e r e i s no d i f f e r e n c e i n t he d i s a p p e a r a n c e r a t e between the two g roups f rom 1.5 t o 12 hou r s p o s t e x p o s u r e . B l o o d g a l l i u m a c t i v i t y a t 12 hours p o s t exposu re was a l s o s i g n i f i c a n t l y h i g h e r i n smoke-exposed a n i m a l s (385 + 413 CPM/g) than c o n t r o l s (36 + 33 CPM/g) ( p < 0 . 0 5 ) a l t h o u g h i t was h i g h l y v a r i a b l e i n t he smoke-exposed g roup ( T a b l e I - p 1 0 2 ) . A i rway i n f l a m m a t i o n s c o r e s f o r c a r t i l a g e n o u s and n o n - c a r t i l a g e n o u s a i rways f o r bo th a n i m a l g roups a re shown i n F i g u r e 2 (p 1 0 4 ) . The v a l u e s shown r e p r e s e n t the mean + SD f o r the s c o r e s f o r each t i s s u e s e c t i o n , thus t a k i n g i n t o a c coun t v a r i a t i o n w i t h i n each a n i m a l as w e l l as between a n i m a l s . C a r t i l a g e n o u s a i rways i n smoke-exposed a n i m a l s had s i g n i f i c a n t l y more i n f l a m m a t i o n than c o n t r o l s ( p ^ 0 . 0 5 ) . N o n - c a r t i l a g e n o u s a i rways were r e m a r k a b l y f r e e o f i n f l a m m a t i o n i n bo th g roups and showed no d i f f e r e n c e between - 85 -smoke-exposed and c o n t r o l a n i m a l s . F i g u r e 3 (p 105) i n d i c a t e s t he t y p e o f i n f l a m m a t i o n seen i n the smoke-exposed a n i m a l s , showing the e x t e n s i v e PMN i n f i l t r a t e b o t h i n the a i rway w a l l and lumen . L i n e a r r e g r e s s i o n a n a l y s i s o f the r e l a t i o n s h i p between g a l l i u m a c t i v i t y r e t a i n e d i n the l u n g s ( a t b o t h t ime p e r i o d s ) and i n f l a m m a t i o n s c o r e s r e v e a l e d no s i g n i f i c a n t p o s i t i v e c o r r e l a t i o n s . Tha t i s , r e t a i n e d g a l l i u m a c t i v i t y was no t i n c r e a s e d i n a n i m a l s w i t h the h i g h e r i n f l a m m a t i o n s c o r e . When the l u n g a c t i v i t y r e m a i n i n g a t 12 hours was e x p r e s s e d as a f r a c t i o n o f the a c t i v i t y p r e s e n t a t 1.5 hou r s ( t o a s s e s s the r e l a t i v e r a t e s o f c l e a r a n c e o f the i s o t o p e d u r i n g t h a t t ime p e r i o d ) , a g a i n , i n c r e a s e d r e t e n t i o n o f the t r a c e r d i d no t c o r r e s p o n d t o a h i g h e r i n f l a m m a t i o n s c o r e . 2. Ga-67 r e t e n t i o n i n human s u b j e c t s I n d i v i d u a l and mean r e s u l t s f o r the d i s a p p e a r a n c e o f g a l l i u m a c t i v i t y f r om the l u n g f i e l d s a re shown i n F i g u r e 4 f o r non-smokers and F i g u r e 5 f o r smokers (p 1 0 7 ) . No d i f f e r e n c e was seen between the two g r o u p s . G a l l i u m a c t i v i t y measured i n the b l o o d i n s i x s u b j e c t s was v e r y l ow , r a n g i n g f rom 0 t o 170 CPM i n the f i r s t hour and a v e r a g i n g 40 CPM a t 24 hours and 10 CPM a t 96 h o u r s . The re was no d i f f e r e n c e i n b l o o d l e v e l s between smokers and non-smokers . F i g u r e s 4 and 5 show t h a t the g a l l i u m a c t i v i t y r e m a i n i n g i n the l u n g s a t 96 hours was not s i g n i f i c a n t l y d i f f e r e n t than t h a t p r e s e n t a t 24 hours p o s t e x p o s u r e . - 86 -3. Ga-67 a u t o r a d i o g r a p h y The t h r e e a n i m a l s exposed t o g a l l i u m a f t e r smoke exposu re a l l showed s i g n i f i c a n t a c t i v i t y i n the l u n g s and l e s s e r amounts i n t he t r a c h e a wh i ch was o n l y p a r t i a l l y removed d u r i n g the d e h y d r a t i o n p r o c e s s ( see T a b l e I I - p 1 0 8 ) . C o n t r o l an ima l s showed no Ga-67 a c t i v i t y o v e r b a c k g r o u n d . L i g h t m i c r o s c o p y on s e c t i o n s f rom Ga-67 exposed a n i m a l s d e v e l o p e d a f t e r 2 weeks , showed o c c a s i o n a l a c c u m u l a t i o n s o f s i l v e r g r a i n s d e p o s i t e d p r e f e r e n t i a l l y o v e r c e l l s on the s u r f a c e o f the s m a l l a i rways wh i ch appear t o be macrophages ( F i g u r e 6 - p 1 0 9 ) . These g r a i n a c c u m u l a t i o n s can be seen o v e r the same c e l l s i n s e r i a l s e c t i o n s o f the t i s s u e . No a c c u m u l a t i o n o f g r a i n s were seen o v e r p o l y m o r p h o n u c l e a r l e u k o c y t e s o r any o t h e r s p e c i f i c c e l l t y p e . 2 The mean r a t i o o f s i l v e r g r a i n s o v e r t h e s e c e l l s pe r mm t o 2 s i l v e r g r a i n s o v e r backg round p e r mm was 67 + 19 (n=30) . The t i s s u e f rom the two an ima l s p r o c e s s e d w i t h i n one hour o f a e r o s o l exposu re a l s o showed some a c c u m u l a t i o n s o f s i l v e r g r a i n s s p r e a d ove r a i rway e p i t h e l i a l c e l l s and mucous w i t h o u t a p p a r e n t c e l l u l a r s p e c i f i c i t y . T h i s was no t seen i n the one an ima l p r o c e s s e d a f t e r 23 h o u r s . T h i s a n i m a l , however , showed more a c t i v i t y i n c e l l s s i t u a t e d on the s u r f a c e o f s m a l l a i r w a y s . No s p e c i f i c a r eas o f a c t i v i t y were appa ren t i n any c a r t i l a g e n o u s a i rways o r i n the t r a c h e a . S i m i l a r r e s u l t s were seen i n the t i s s u e f rom the one human - 87 -p a t i e n t s t u d i e d ( F i g u r e 7 - p 1 1 0 ) . S i l v e r g r a i n a c c u m u l a t i o n s were seen o v e r some c e l l s wh i ch appea red t o be macrophages a d j a c e n t t o s m a l l a i rways and i n the a l v e o l a r s p a c e s . No o t h e r c e l l t y p e s i n d i c a t e d a c c u m u l a t i o n o f the i s o t o p e . The number o f macrophages wh i ch showed s i l v e r g r a i n a c c u m u l a t i o n s compared t o the t o t a l number o f macrophages p r e s e n t i n the t i s s u e was v e r y s m a l l . The r a t i o o f c e l l c oun t s t o backg round i n t h i s case was 95 + 20 (n = 1 0 ) . - 88 -D i s c u s s i o n The r e s u l t s o f t h i s s e r i e s o f expe r imen t s i n d i c a t e t h a t l a b e l l i n g o f a i rway p o l y m o r p h o n u c l e a r l e u k o c y t e s does no t o c c u r w i t h the i n h a l a t i o n o f a e r o s o l i z e d g a l l i u m - 6 7 and t h a t c i g a r e t t e smoke exposu re does no t i n c r e a s e the r e t e n t i o n t ime o f t h i s i s o t o p e i n the l u n g s . The g u i n e a p i g e x p e r i m e n t s compar ing g a l l i u m r e t e n t i o n i n smoke-exposed v e r s u s c o n t r o l an ima l s had s e v e r a l p o t e n t i a l m e t h o d o l o g i c a l s o u r c e s o f e r r o r wh i ch make i n t e r p r e t a t i o n o f t he r e s u l t s d i f f i c u l t . A l t h o u g h t h e r e appea red t o be a g r e a t e r amount o f i s o t o p e r e t a i n e d by the smoke-exposed a n i m a l s , the f a c t t h a t the r a t i o between smoke-exposed and c o n t r o l s d i d no t change f r om 1.5 t o 12 h o u r s , shows t h a t the o n l y p o s s i b l e d i f f e r e n c e i n r e t e n t i o n between the g roups must have been r e l a t e d t o e v e n t s o c c u r r i n g b e f o r e the f i r s t imag ing a t 1.5 h o u r s . T h i s c o u l d o c c u r i n one o r more o f t h r e e ways : f i r s t l y , the c o n t r o l a n i m a l s c o u l d have c l e a r e d more o f the i s o t o p e by m u c o c i l i a r y a c t i o n d u r i n g t h i s t ime p e r i o d ; s e c o n d l y , t h e r e c o u l d have been i n c r e a s e d t r a n s f e r o f the i s o t o p e i n t o the b l o o d i n c o n t r o l s , e i t h e r as a r e s u l t o f more p e r i p h e r a l d e p o s i t i o n o r l e s s t i s s u e b i n d i n g ; o r t h i r d l y , the smoke-exposed an ima l s c o u l d have had g r e a t e r d e p o s i t i o n o f the i s o t o p e i n the f i r s t p l a c e . However when the r e t e n t i o n a t 1.5 hours was r e c a l c u l a t e d based on the whole body image i n s t e a d o f the c h e s t o n l y , the a c t i v i t y was a p p r o x i m a t e l y d o u b l e i n - 89 -b o t h smoke-exposed and c o n t r o l s bu t the r a t i o o f the two was i d e n t i c a l t o t he r a t i o based on c o u n t i n g o v e r the c h e s t o n l y . T h i s s u g g e s t s t h a t f a s t e r c l e a r a n c e i n the c o n t r o l s ( e i t h e r t o the b l o o d o r t o t he gu t ) was no t r e s p o n s i b l e f o r the h i g h e r a c t i v i t y i n the smoke-exposed a n i m a l s . I t i s a l s o u n l i k e l y t h a t g r e a t e r c l e a r a n c e c o u l d have o c c u r r e d i n c o n t r o l s v i a u r i n a r y e x c r e t i o n as t h i s does no t o c c u r r a p i d l y enough t o a c c o u n t f o r the d i f f e r e n c e seen ( 3 2 ) . I n c r e a s e d d e p o s i t i o n i n the smoke-exposed a n i m a l s appea rs t o be the o n l y e x p l a n a t i o n f o r the i n c r e a s e d a c t i v i t y seen i n t h i s g roup a t b o t h t ime p e r i o d s . T h i s c o u l d o c c u r as a r e s u l t o f a i rway n a r r o w i n g e i t h e r by c o n s t r i c t i o n o f b r o n c h i a l smooth musc l e o r by i n c r e a s e d mucous p r o d u c t i o n . The i n f l a m m a t i o n seen i n the l u n g s o f t he smoke-exposed an ima l s was c o n f i n e d t o t he c a r t i l a g e n o u s a i r w a y s . T h i s i n d i c a t e s t h a t the c i g a r e t t e smoke a c t s a t t h i s l e v e l i n t h e s e a n i m a l s and c o u l d w e l l r e s u l t i n s i g n i f i c a n t na r r ow i n g o f t h e s e a i r w a y s . A n o t h e r p o s s i b l e mechanism f o r i n c r e a s e d d e p o s i t i o n i s an i n c r e a s e i n m inu te v e n t i l a t i o n i n the smoke-exposed a n i m a l s , pe rhaps r e l a t e d t o t h e i r p r e v i o u s u n c o m f o r t a b l e e x p e r i e n c e i n the exposu re chamber . T h i s was no t s u b j e c t i v e l y appa ren t t o o b s e r v a t i o n d u r i n g the e x p e r i m e n t , as b o t h g roups o f a n i m a l s appea red t o t o l e r a t e t he g a l l i u m a e r o s o l w e l l . However , no measurements were made o f t i d a l vo lume o r r e s p i r a t o r y f r e q u e n c y , t o c o n f i r m o r deny t h i s p o s s i b i l i t y . However , the i n c r e a s e d l e v e l o f g a l l i u m seen i n the smoke-exposed an ima l s i s c l e a r l y no t r e l a t e d t o the degree o f - 90 -i n f l a m m a t i o n i n the a i r w a y s . T h i s i s borne ou t by the f a i l u r e t o f i n d a s i g n i f i c a n t c o r r e l a t i o n between g a l l i u m a c t i v i t y a t e i t h e r t ime p e r i o d and a i rway i n f l a m m a t i o n s c o r e s . Even i f the g a l l i u m a c t i v i t y p r e s e n t a t 1.5 hours i s assumed t o r e f l e c t the dose r e c e i v e d by the a n i m a l , t hen the r a t i o o f the a c t i v i t y a t 12 hours t o t h a t a t 1.5 hours wou ld r e p r e s e n t the c l e a r a n c e p r o f i l e d u r i n g t h a t t ime p e r i o d . I f the o r i g i n a l h y p o t h e s i s was c o r r e c t , t hen a h i g h r a t i o ( o r s low c l e a r a n c e ) wou ld c o r r e s p o n d t o a h i g h i n f l a m m a t i o n s c o r e . Such a r e l a t i o n s h i p was not f o u n d i n t h e s e a n i m a l s . The r e s u l t s show c l e a r l y , t h e n , t h a t the p r e s e n c e o f i n f l a m m a t o r y c e l l s i n the a i rways as a r e s u l t o f c i g a r e t t e smoke exposu re does no t r e s u l t i n i n c r e a s e d g a l l i u m r e t e n t i o n . T h i s i s f u r t h e r c o n f i r m e d by the human s t u d y . The i n t e r e s t i n g f i n d i n g i n t h i s e x p e r i m e n t , i n a d d i t i o n t o c o n f i r m i n g the l a c k o f i n c r e a s e d r e t e n t i o n i n smoke r s , was the r e m a r k a b l y s low c l e a r a n c e f rom 24 t o 96 hours i n a l l s u b j e c t s . T h i s i n d i c a t e s t h a t more than h a l f o f the i n h a l e d dose became bound t o t i s s u e o r c e l l s i n the l u n g s . The e x t r e m e l y low b l o o d l e v e l s a t a l l t ime p e r i o d s seen i n t h e s e s u b j e c t s , b o t h smokers and non-smokers , i s f u r t h e r e v i d e n c e t h a t the g a l l i u m a c t i v i t y i s r e s i d e n t i n the l u n g t i s s u e . The s t u d i e s u s i n g l i g h t m i c r o s c o p i c a u t o r a d i o g r a p h y p r o v i d e the i n f o r m a t i o n wh i ch a l l o w s f u r t h e r i n t e r p r e t a t i o n o f t h e s e e x p e r i m e n t a l r e s u l t s . The g u i n e a p i g s exposed t o c i g a r e t t e smoke had a p o l y m o r p h o n u c l e a r i n f i l t r a t e i n the c a r t i l a g e n o u s a i rways but t h e s e c e l l s showed no up take o f the g a l l i u m . On l y macrophages p r e s e n t on - 91 -the s u r f a c e o f p e r i p h e r a l a i rways showed e v i d e n c e o f g a l l i u m a c c u m u l a t i o n . T h i s and the s i m i l a r f i n d i n g i n the human t i s s u e s u g g e s t t h a t the g a l l i u m p e n e t r a t e s t o the s m a l l a i rways and a l v e o l i where i t becomes a t t a c h e d t o o r i n g e s t e d by mac rophages . T h i s wou ld a c coun t f o r the v e r y s low c l e a r a n c e i n the human s u b j e c t s , a f t e r the i n i t i a l d r o p i n the f i r s t 24 h o u r s . T h i s i n i t i a l d e c r e a s e i s l i k e l y due t o m u c o c i l i a r y c l e a r a n c e o f the i s o t o p e wh i ch may be d e p o s i t e d i n mucous and pe rhaps b i n d s t o l a c t o f e r r i n p r e s e n t i n the mucous ( 6 4 ) . C i g a r e t t e smokers have been shown t o have an e x c e s s o f macrophages i n r e s p i r a t o r y b r o n c h i o l e s ( 1 8 ) . I f t h i s i s the c a s e , and the g a l l i u m accumu la t e s i n t h e s e c e l l s , why was t h e r e not any i n c r e a s e i n r e t e n t i o n i n the smokers? The answer t o t h i s may a g a i n l i e i n t he a u t o r a d i o g r a p h i c s t u d i e s . The dose o f i s o t o p e g i v e n t o the human s u b j e c t s was e x t r e m e l y l ow , i n k e e p i n g w i t h the e x p e r i m e n t a l n a t u r e o f the s t u d y . The t i s s u e f r om the one human s u b j e c t wh i ch was p r o c e s s e d f o r a u t o r a d i o g r a p h y shows t h a t o n l y a v e r y s m a l l p r o p o r t i o n o f the macrophages p r e s e n t had a c cumu la t ed any s i g n i f i c a n t q u a n t i t y o f the i s o t o p e . In o r d e r t o see any d i f f e r e n c e between smokers and non-smokers a much h i g h e r dose wou ld have t o be g i v e n . T h i s i s , i n f a c t , the case w i t h i n j e c t e d g a l l i u m s t u d i e s . The dose i n j e c t e d i s a p p r o x i m a t e l y e q u a l t o the a c t i v i t y p r e s e n t i n the n e b u l i z e r i n t h i s s t u d y ( o f wh i ch l e s s than 5% i s d e p o s i t e d ) , and the r e s u l t s o f t h e s e scans do c o r r e l a t e p o s i t i v e l y w i t h the p r e s e n c e o f a l v e o l i t i s . On l y v e r y few s t u d i e s have been r e p o r t e d i n the l i t e r a t u r e wh i ch s p e c i f i c a l l y i m p l i c a t e macrophages i n g a l l i u m a c c u m u l a t i o n . - 92 -Hayes and h i s c o l l e a g u e s (42) have r e c e n t l y h y p o t h e s i z e d t h a t p h a g o c y t o s i s o f p r o t e i n - b o u n d g a l l i u m - 6 7 by macrophages was r e s p o n s i b l e f o r i n f l a m m a t o r y a c c u m u l a t i o n and he p o i n t e d f o r e v i d e n c e t o an e a r l i e r a u t o r a d i o g r a p h i c s t udy by Swa r t zend rube r and Idoyaga-Vargas (65) i n wh i ch g a l l i u m was seen t o a c cumu la t e p r e f e r e n t i a l l y i n macrophages ove r g r a n u l o c y t e s , d e s p i t e e q u a l p h a g o c y t o s i s o f l a t e x p a r t i c l e s by bo th c e l l t y p e s . In a p r e v i o u s s t udy on m i c e , Swa r t zend rube r and a s s o c i a t e s (34) had d e m o n s t r a t e d g a l l i u m a c c u m u l a t i o n n o t a b l y i n macrophages o f the l y m p h o r e t i c u l a r s y s t e m , i n thymic e p i t h e l i a l r e t i c u l a r c e l l s , K u p f f e r c e l l s , h e p a t i c c e l l s , and k i d n e y c e l l s o f the p r o x i m a l c o n v o l u t e d t u b u l e s . In an a b s t r a c t , i n 1981 , Hunninghake and h i s c o l l e a g u e s (58) r e p o r t e d c o r r e l a t i o n between b r o n c h o a l v e o l a r l a v a g e c e l l u l a r i t y and p o s i t i v e g a l l i u m scans i n p a t i e n t s w i t h i n t e r s t i t i a l l u n g d i s e a s e . In e i g h t p a t i e n t s w i t h i d i o p a t h i c pu lmonary f i b r o s i s , 66% o f the a c t i v i t y i n t he l a v a g e was a s s o c i a t e d w i t h macrophages and 34% w i t h n e u t r o p h i l s . In 10 s a r c o i d p a t i e n t s , 95% was a s s o c i a t e d w i t h macrophages and 5% w i t h T - l y m p h o c y t e s . C l e a r l y , the p r e v i o u s l y h e l d n o t i o n t h a t g a l l i u m a c c u m u l a t i o n i n a r ea s o f i n f l a m m a t i o n i s due t o a t t achment t o p o l y m o r p h o n u c l e a r l e u k o c y t e s needs r e - e v a l u a t i o n i n l i g h t o f t he se r e p o r t s and the r e s u l t s o f t h i s s t u d y . A c c u m u l a t i o n by a c t i v a t e d i n f l a m m a t o r y and immune e f f e c t o r c e l l s , p a r t i c u l a r l y macrophages as p o s t u l a t e d by Hayes ( 4 2 ) , appea r s t o be the most l i k e l y mechan ism. In summary, t h i s s e r i e s o f e x p e r i m e n t s s u p p o r t s the - 93 -h y p o t h e s i s t h a t g a l l i u m - 6 7 accumu la t e s i n mac rophages . However , t he p o t e n t i a l f o r u s i n g a e r o s o l i z e d g a l l i u m i n h a l a t i o n t o mark the a cu t e p o l y m o r p h o n u c l e a r l e u k o c y t e r e s p o n s e t o c i g a r e t t e smoke has been shown t o be m i n i m a l , as the g a l l i u m does not appear t o b i n d t o PMN 's . However , t he b i n d i n g t o macrophages may have p o t e n t i a l v a l u e i n s t u d y i n g the a c t i v i t y o f t h i s c e l l i n o t h e r l u n g d i s o r d e r s . - 94 -REFERENCES - CHAPTER V 1. Hogg J C , Macklem PT , T h u r l b e c k WM: S i t e and n a t u r e o f a i rway o b s t r u c t i o n i n c h r o n i c o b s t r u c t i v e l u n g d i s e a s e . New E n g l J Med 1968 ; 278 :1355-1360 2. Macklem PT , Mead J : R e s i s t a n c e o f c e n t r a l and p e r i p h e r a l a i rways measured by a r e t r o g r a d e c a t h e t e r . J A p p l P h y s i o l 1967 ; 22 :395-401 3. R e i d LM: C o r r e l a t i o n s o f c e r t a i n b r o n c h o g r a p h i c a b n o r m a l i t i e s seen i n c h r o n i c b r o n c h i t i s w i t h the p a t h o l o g i c a l c h a n g e s . Tho rax 1955 ; 10 :199-205 4 . McLean KH: The p a t h o l o g y o f emphysema. Am Rev R e s p i r D i s 1959 ; 80 :58-64 5. Ande r son A E , F o r a k e r AG : R e l a t i v e d i m e n s i o n s o f b r o n c h i o l e s and pa renchyma l spaces i n l u n g s f rom norma l s u b j e c t s and emphysematous p a t i e n t s . Am J Med 1962 ; 32 :218-226 6. S p a i n DM, Kaufman G: The b a s i c l e s i o n i n c h r o n i c pu lmonary emphysema. Am Rev T u b e r c 1953 ; 68 :24-30 7. B ignon J , Khoury F, Even P, Andre J , B r oue t G: Mo rphomet r i c s t udy i n c h r o n i c o b s t r u c t i v e b ronchopu lmonary d i s e a s e . Am Rev R e s p i r D i s 1969 ; 99 :669-695 8. 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Ba ton Rouge: C l a i t o r ' s P u b l i s h i n g D i v i s i o n , 1973:404-405 - 102 -TABLE I Ga-67 B l o o d L e v e l s @ 12 Hours Pos t Exposu re (CPM/G. Wet Wt. ) C o n t r o l Smoke Exposed 38 30 6 440 64 1076 0 208 74 172 36 .4 + 3 3 . 3 385 + 413 .3 P < 0 . 0 5 - 103 -A I R W A Y I N F L A M A T I O N . 6 . 2 1 C A R T I L A G E N O U S A I R W A Y S ( P < . 0 5 ) N O N - C A R T I L A G E N O U S A I R W A Y S Figure 1 Gamma camera measurement of 'Gallium a c t i v i t y i n lungs of c o n t r o l (C) and smoke-exposed (S) animals at 1.5 and 12 hours a f t e r i n h a l a t i o n , expressed as a f r a c t i o n of the a c t i v i t y i n the amount of gallium nebulized, showing much greater retention i n the smoke-exposed animals, (n = 5 for each group) - 104 -GA RETENTION IN GUINEA P I G LUNGS 5 HR. (P< 01) ,003 .002 • .001 • 12 HR. (P<.02) I n f l a m m a t i o n s c o r e s f o r c a r t i l a g e n o u s and n o n - c a r t i l a g e n o u s a i rways ( see t e x t f o r d e s c r i p t i o n ) f o r c o n t r o l (C) and smoke-exposed (S) a n i m a l s , n=35 s e c t i o n s , c o n t r o l s ; n=33 s e c t i o n s , smoke-exposed . O n l y c a r t i l a g e n o u s a i r w a y s i n the smoke-exposed g roup had s i g n i f i c a n t l y more i n f l a m m a t o r y i n f i l t r a t e . - 105 -s u r e 3 P h o t o m i c r o g r a p h o f a p o r t i o n o f a c a r t i l a g e n o u s a i rway f r om a smoke-exposed g u i n e a p i g 12 hours a f t e r smoke-exposure , showing e x t e n s i v e p o l y m o r p h o n u c l e a r l e u k o c y t e (PMN) i n f i l t r a t i o n bo th i n the w a l l and lumen . ( O r i g i n a l m a g n i f i c a t i o n : 160x) - 106 -F i g u r e s A and 5 G a l l i u m a c t i v i t y i n human s u b j e c t s as a p e r c e n t a g e o f the i n i t i a l a c t i v i t y i n h a l e d , showing i n i t i a l d e c r e a s e i n a c t i v i t y between 0 and 24 hou r s and no f u r t h e r change 96 hours a f t e r e x p o s u r e . Note no d i f f e r e n c e i n r e t e n t i o n between (a) non-smokers and (b) smokers . - 107 -Figure 4 NON-SMOKERS < 24 96 T I M E (HOURS) Figure 5 SMOKERS 24 96 T I M E (HOURS) - 108 -TABLE I I Ga-67 A c t i v i t y o f Lungs and T r a c h e a o f Ga-67-exposed G u i n e a P i g s A n i m a l 1 A n i m a l 2 A n i m a l 3 b e f o r e a f t e r % b e f o r e a f t e r % (CPM/g.wet w t . ) d e h y d r . d e h y d r . d e h y d r . d e h y d r . T r a c h e a 4448 10 ,028 7401 74 2599 1223 47 I nne r segment l u n g 24 ,084 53,107 35 ,572 67 35 ,926 31 ,227 87 M i l d segment l u n g 21 ,227 26 ,247 16 ,625 63 51,213 44 ,694 87 O u t e r segment l u n g 21 ,244 69 ,498 40 ,609 58 43 ,572 37 ,715 87 - 109 -Figure 6 Autoradiographs from lung sections taken from three guinea pigs exposed to c i g a r e t t e smoke. (a,b,c): S i l v e r grain accumulations ( ) over c e l l s on the surface of small airways which appear to be macrophages ( o r i g i n a l magnification 160x). (d): Higher power view of c e l l indicated i n ( c ) . (O r i g i n a l magnification: 400x) - 110 -A u t o r a d i o g r a p h s o f l u n g s e c t i o n s t aken f rom the one human s u b j e c t , showing s i l v e r g r a i n a c c u m u l a t i o n s ( ) o v e r a l v e o l a r mac rophages . N o t i c e r e l a t i v e absence o f g r a i n s e l s ewhe re ove r t i s s u e o r b a c k g r o u n d . ( O r i g i n a l m a g n i f i c a t i o n : 400x) - I l l -V I . A i rway M u c o s a l P e r m a b i l i t y and R e a c t i v i t y I n t r o d u c t i o n : A r e l a t i o n s h i p between a i rway mucosa l damage and the i n c r e a s e d a i rway r e a c t i v i t y commonly seen among i n d i v i d u a l s a f t e r upper r e s p i r a t o r y t r a c t v i r a l i n f e c t i o n o r exposu re t o p o l l u t a n t s was f i r s t p r o p o s e d by Nade l and h i s c o l l e a g u e s ( 1 , 2 , 3 ) . They s t u d i e d norma l n o n - a t o p i c i n d i v i d u a l s a f t e r i n f e c t i o n (1) and a f t e r exposu re t o low l e v e l s o f ozone ( 1 , 3 , 4 ) and f o u n d a t r a n s i e n t h y p e r - r e a c t i v i t y t o b o t h h i s t a m i n e , c i t r i c a c i d , and m e t h a c h o l i n e . Repea ted ozone exposu re (3) r e s u l t e d i n a d a p t a t i o n such t h a t the h y p e r - r e a c t i v i t y t o h i s t a m i n e d i s a p p e a r e d even when ozone exposu re was c o n t i n u e d . A t r o p i n e p r e t r e a t m e n t b l o c k e d the r e a c t i v i t y i n c r e a s e ( 1 ) , s u g g e s t i n g i n v o l v e m e n t o f c h o l i n e r g i c i r r i t a n t r e c e p t o r s . The f a c t t h a t the s u b j e c t s were p r e v i o u s l y h e a l t h y and had norma l s p i r o m e t r y , even a f t e r the i n f e c t i o n o r e x p o s u r e , r u l e d ou t a l t e r a t i o n s i n b a s e l i n e a i rway c a l i b r e , h y p e r t r o p h y o r h y p e r p l a s i a o f a i rway smooth m u s c l e , and c h r o n i c a l l e r g i c d i s e a s e as i m p l i c a t e d i n the r e s p o n s e . These i n v e s t i g a t o r s p r o p o s e d t h a t t he e p i t h e l i a l damage (desquamat ion and d e g e n e r a t i o n ) wh i ch has been i d e n t i f i e d a f t e r v i r a l i n f e c t i o n o r exposu re t o a i r b o r n e i r r i t a n t s r e s u l t s i n \" s e n s i t i z a t i o n \" o r i n c r e a s e d a c c e s s i b i l i t y o f the r a p i d l y a d a p t i n g e p i t h e l i a l r e c e p t o r s . The f a c t t h a t r e a c t i v i t y i n c r e a s e d i n r e s p o n s e t o - 112 -m e t h a c h o l i n e c h a l l e n g e i n the s u b j e c t s exposed t o ozone (2) s u g g e s t e d i n c r e a s e d p o s t - g a n g l i o n i c c h o l i n e r g i c s e n s i t i v i t y as w e l l as s e n s i t i z a t i o n o f i r r i t a n t r e c e p t o r s . The a u t h o r s h y p o t h e s i z e d t h a t t h i s c o u l d r e s u l t f r om an i n c r e a s e i n the p e r m e a b i l i t y o f the a i rway e p i t h e l i u m , a l l o w i n g more a g o n i s t to r e a c h bo th i r r i t a n t r e c e p t o r s and the b r o n c h i a l smooth m u s c l e . S i m i l a r i n c r e a s e s i n n o n - s p e c i f i c r e a c t i v i t y t o i n h a l e d p h a r m a c o l o g i c agen ts a re a l s o seen i n a t o p i c s u b j e c t s f o l l o w i n g s p e c i f i c a n t i g e n c h a l l e n g e ( 5 , 6 ) , c h r o n i c a n t i g e n exposu re ( 7 , 8 ) , and exposu re t o o t h e r e n v i r o n m e n t a l agents ( 9 ) ; and i n some n o n - a t o p i c s u b j e c t s f o l l o w i n g the deve lopment o f o c c u p a t i o n a l asthma ( 8 , 1 0 , 1 1 ) . In a d d i t i o n t o the h y p o t h e s i s t h a t t h i s i n c r e a s e d r e a c t i v i t y i s a s s o c i a t e d w i t h a l t e r e d e p i t h e l i a l p e r m e a b i l i t y , o t h e r mechanisms have been p r o p o s e d . Some i n v e s t i g a t o r s have p o s t u l a t e d t h a t a r e d u c t i o n i n t he s t a r t i n g c a l i b r e o f the a i rways c o u l d a c coun t f o r the h y p e r - r e a c t i v i t y as r e s i s t a n c e t o a i r f l o w v a r i e s i n v e r s e l y w i t h the f o u r t h power o f the a i rway r a d i u s ( 1 2 , 1 3 ) , thus a s i m i l a r deg ree o f n a r r o w i n g may cause d i f f e r i n g d e c r e a s e s i n a i r f l o w i f the s t a r t i n g r a d i u s i s d i f f e r e n t . However s t u d i e s i n norma l s u b j e c t s such as t h o s e d e s c r i b e d above ( 3 ,4 ) have demons t r a t ed t h a t h y p e r - r e a c t i v i t y d e v e l o p s i n s u b j e c t s i n wh i ch t h e r e i s no appa ren t change i n a i rway c a l i b r e . A b n o r m a l i t i e s o r a l t e r a t i o n s i n the a i rway smooth musc l e have a l s o been p r o p o s e d t o a c c o u n t f o r enhanced n o n - s p e c i f i c r e a c t i v i t y . I n c r e a s e d \" s e n s i t i v i t y \" o f the musc l e as a r e s u l t o f exposu re t o t o x i n s has been h y p o t h e s i z e d as has c o n v e r s i o n o f a i rway smooth musc l e - 113 -f rom a m u l t i - u n i t t o a s i n g l e u n i t o r s c y n c y t i u m ; however , no r e a l e v i d e n c e has been p r e s e n t e d t o s u p p o r t t h e s e c o n c e p t s ( 1 4 ) . A l t e r a t i o n s i n the c o n t r o l o f a i rway smooth musc l e may a l s o a c c o u n t f o r the h y p e r - r e a c t i v i t y . S z e n t i v a n y i (15) f o r m u l a t e d the b e t a - a d r e n e r g i c b l o c k a d e t h e o r y o f asthma i n wh i ch he p o s t u l a t e d t h a t d e c r e a s e d r e s p o n s i v e n e s s o f b e t a - a d r e n e r g i c r e c e p t o r s r e s p o n s i b l e f o r a i rway r e l a x a t i o n a l l o w e d unopposed a l p h a - a d r e n e r g i c s t i m u l a t i o n o f a i rway smooth m u s c l e . S e v e r a l worke rs have i n v e s t i g a t e d the e f f e c t s o f b e t a - a d r e n e r g i c a n t a g o n i s t s and found t h a t w h i l e a s t h m a t i c s r e s p o n d s i g n i f i c a n t l y t o p r o p r a n o l o l w i t h b r o n c h o c o n s t r i c t i o n ( 1 6 ) , no rma l s u b j e c t s r e s p o n d o n l y s l i g h t l y (17) o r no t a t a l l ( 18 , 1 9 ) . In c e r t a i n s t u d i e s however , o f smokers (17 ,20 ) o r worke rs exposed t o o c c u p a t i o n a l a n t i g e n s ( 2 1 ) , p r o p r a n o l o l t r e a t m e n t has r e s u l t e d i n s i g n i f i c a n t l y enchanced r e a c t i v i t y . A n o n - a d r e n e r g i c i n h i b i t o r y ne rvous sys tem has been d e m o n s t r a t e d i n v i t r o (22) and p r o p o s e d t o be the major sys tem f o r i n h i b i t i o n o f b r o n c h i a l smooth musc l e c o n s t r i c t i o n . A d e f e c t o r a l t e r a t i o n i n t h i s s ys tem c o u l d a ccoun t f o r a i rway h y p e r - r e a c t i v i t y . C o n v e r s e l y , an a b n o r m a l i t y i n the p a r a s y m p a t h e t i c ne rvous sys tem c o u l d r e s u l t i n i n c r e a s e d s t i m u l a t i o n o f b r o n c h i a l smooth m u s c l e . V a g a l m e d i a t i o n o f the e f f e c t s o f v a r i o u s s t i m u l i wh ich i n d u c e h y p e r - r e a c t i v i t y has been d e m o n s t r a t e d by the r e d u c t i o n i n r e a c t i v i t y a f t e r a t r o p i n e a d m i n i s t r a t i o n ( 1 , 2 3 , 2 4 ) . However i n the s t u d y o f ozone exposu re d e s c r i b e d above ( 4 ) , Ho l tzman and c o l l e a g u e s f ound t h a t the r e s p o n s e t o m e t h a c h o l i n e was not a l t e r e d i n the p r e s e n c e o f the - 114 -g a n g l i o n i c b l o c k i n g agent hexamethonium, s u g g e s t i n g a d i r e c t r a t h e r than r e f l e x a c t i o n on b r o n c h i a l smooth m u s c l e . In a d d i t i o n , a l t h o u g h ozone exposu re r e s u l t s i n enhanced r e a c t i v i t y i n v i v o , i n v i t r o i n v e s t i g a t i o n o f dog v a g a l a f f e r e n t f i b r e s a f t e r ozone e x p o s u r e i n d i c a t e d d e c r e a s e d s e n s i t i v i t y t o h i s t a m i n e ( 2 5 ) . These c o n t r a d i c t o r y r e s u l t s have s u g g e s t e d t h a t i n c r e a s e d a c c e s s t o , r a t h e r than i n c r e a s e d s e n s i t i v i t y o f , i r r i t a n t r e c e p t o r s may be the p a t h o g e n e t i c e ven t i n h y p e r - r e a c t i v i t y . T h u s , mucosa l i n f l a m m a t i o n o r damage wh i ch r e s u l t s i n such an i n c r e a s e i n a c c e s s i b i l i t y emerges a g a i n as p o t e n t i a l l y i m p o r t a n t i n the deve lopment o f n o n - s p e c i f i c b r o n c h i a l r e a c t i v i t y . M u c o s a l i n f l a m m a t i o n has a l s o been p r o p o s e d to a ccoun t f o r the d e l a y e d a s t h m a t i c r e s p o n s e as w e l l as t he i n c r e a s e d n o n - s p e c i f i c r e a c t i v i t y seen i n many i n d i v i d u a l s a f t e r exposu re t o c e r t a i n a i r b o r n e d u s t , v a p o u r s , o r fumes i n the w o r k p l a c e ( 5 , 6 , 8 , 1 0 , 1 1 ) . T h i s o c c u p a t i o n a l asthma g e n e r a l l y d e v e l o p s o v e r t ime w i t h a symptom-free p e r i o d f o l l o w e d by s e n s i t i z a t i o n . The p r o v o k i n g agents a re c h e m i c a l l y he t e rogeneous and o f t e n , no t a l l e r g e n s ( 2 6 ) . L a b o r a t o r y c h a l l e n g e w i t h the p r o v o k i n g agent i nduces e i t h e r an immediate a s t h m a t i c r e s p o n s e and/or a d e l a y e d r e s p o n s e . A s s o c i a t e d w i t h the a s t h m a t i c o b s t r u c t i o n , bu t p e r s i s t i n g even when the a i rway o b s t r u c t i o n has d i s a p p e a r e d ( 6 , 1 0 , 1 1 ) i s the i n c r e a s e i n n o n - s p e c i f i c a i rway r e s p o n s i v e n e s s . Lam and co-workers (8) r e p o r t e d t h i s i n c r e a s e i n a l l p a t i e n t s exposed t o Wes te rn Red Ceda r r e g a r d l e s s o f whether o r no t t hey had an immediate o r a d e l a y e d r e a c t i o n , whereas C o c k c r o f t and - 115 -c o l l e a g u e s (5) f o u n d i t o n l y i n a s s o c i a t i o n w i t h the d e l a y e d a s t h m a t i c r e s p o n s e . The h y p e r - r e a c t i v i t y e v e n t u a l l y r e t u r n s t o norma l a f t e r c e s s a t i o n o f exposu re i n some s u b j e c t s but p e r s i s t s i n o t h e r s ( 8 ) . C a r t i e r and c o l l e a g u e s (6) have p r o v i d e d a d d i t i o n a l e v i d e n c e o f a r e l a t i o n s h i p between the h y p e r - r e a c t i v i t y and the d e l a y e d a s t h m a t i c r e s p o n s e , showing t h a t the magn i tude o f the a s t h m a t i c r e s p o n s e c o r r e l a t e s p o s i t i v e l y w i t h the magn i tude and d u r a t i o n o f the i n c r e a s e i n r e a c t i v i t y t o h i s t a m i n e , s u g g e s t i n g t h a t the h y p e r - r e a c t i v i t y may be i n d u c e d by the same mechanisms wh i ch cause the d e l a y e d r e s p o n s e , name l y , m u c o s a l i n f l a m m a t i o n w i t h i n c r e a s e d e p i t h e l i a l p e r m e a b i l i t y . The c o n c e p t t h a t a l t e r e d mucosa l p e r m e a b i l i t y may be r e l a t e d t o the p a t h o g e n e s i s o f asthma was f i r s t p r o p o s e d i n 1929 by Cohen and co-workers (27) who measured the t ime r e q u i r e d a f t e r a n t i g e n i n h a l a t i o n f o r r e a c t i o n w i t h s p e c i f i c a n t i b o d y i n j e c t e d i n t o t he s k i n . A s t h m a t i c s showed a d e l a y e d r e a c t i o n , i n d i c a t i n g d e c r e a s e d r a t e o f t r a n s f e r f rom l u n g s t o b l o o d . S i m i l a r r e s u l t s have been r e p o r t e d more r e c e n t l y by B r a l e y and a s s o c i a t e s (28) who found r e d u c e d a n t i g e n a b s o r p t i o n i n the i s o l a t e d l u n g s o f immunized r a b b i t s compared t o non- immun ized . However , S a l v a g g i o and L e s k o w i t z and t h e i r c o l l e a g u e s (29 ,30 ) have s u g g e s t e d t h a t p a t i e n t s w i t h a t o p i c r h i n i t i s may have a d e f e c t i n the n a s a l mucosa wh i ch a l l o w s i n h a l e d a n t i g e n s g r e a t e r a c c e s s t o immunocompetent c e l l s . B u c k l e and co-workers (31) d e m o n s t r a t e d more r a p i d a b s o r p t i o n o f l a b e l l e d a lbumin f rom the n a s a l mucosa i n p a t i e n t s w i t h a l l e r g i c r h i n i t i s , a l t h o u g h t h i s d i d no t o c c u r i n p a t i e n t s w i t h - 116 -e x t r i n s i c as thma. They s u g g e s t e d t h a t pe r sons w i t h a t o p i c r h i n i t i s may have enhanced p e r m e a b i l i t y i n the n a s a l mucosa w h i l e a s t h m a t i c s may have enhanced b r o n c h i a l p e r m e a b i l i t y . E v i d e n c e t h a t enchanced p e r m e a b i l i t y may p l a y a r o l e i n a c q u i r e d n o n - s p e c i f i c r e a c t i v i t y was p r o v i d e d by Matsumura and c o l l e a g u e s (32) who f o u n d i n c r e a s e d r a t e o f a b s o r p t i o n o f a l bumin i n g u i n e a p i g l u n g s a f t e r exposu re t o o z o n e . These an ima l s were a l s o shown t o have enhanced r e a c t i v i t y t o i n h a l e d a n t i g e n a f t e r the ozone exposu re ( 3 3 ) . More r e c e n t i n v e s t i g a t i o n o f the e f f e c t s o f ozone i n g u i n e a p i g l u n g s by D a v i s and co-workers (34) has demons t r a t ed i n c r e a s e d a i rway e p i t h e l i a l p e r m e a b i l i t y t o h o r s e r a d i s h p e r o x i d a s e (HRP) . S p e c i f i c i n v e s t i g a t i o n o f the r e l a t i o n s h i p between e p i t h e l i a l p e r m e a b i l i t y and h y p e r - r e a c t i v i t y was c a r r i e d ou t by Boucher and h i s c o l l e a g u e s (35) who s t u d i e d n a t u r a l l y a s c a r i s - s e n s i t i v e monkeys . They f o u n d no d i f f e r e n c e i n b a s e l i n e p e r m e a b i l i t y between the a l l e r g i c and n o n - a l l e r g i c monkeys ; however , a n t i g e n c h a l l e n g e l e a d t o i n c r e a s e d p e r m e a b i l i t y t o a lbumin i n the a l l e r g i c a n i m a l s wh i ch p e r s i s t e d w e l l a f t e r the r e s p i r a t o r y mechan i c s had r e t u r n e d t o n o r m a l . F u r t h e r s t u d y (36) i n d i c a t e d t h a t a n t i g e n c h a l l e n g e i n the monkeys was f o l l o w e d by enhanced r e a c t i v i t y t o h i s t a m i n e and i n c r e a s e d p e r m e a b i l i t y t o t r i t i u m - l a b e l l e d h i s t a m i n e . S i m i l a r l y , i n the g u i n e a p i g , h i s t a m i n e and m e t h a c h o l i n e c h a l l e n g e r e s u l t e d i n i n c r e a s e d e p i t h e l i a l p e r m e a b i l i t y t o h o r s e r a d i s h p e r o x i d a s e (HRP) ( 3 7 ) . C i g a r e t t e smoke exposu re was e a r l i e r i d e n t i f i e d by S iman i and - 117 -h i s c o l l e a g u e s (38) as c a u s i n g i n c r e a s e d t r a c h e a l e p i t h e l i a l p e r m e a b i l i t y t o HRP and Boucher and co-workers (39) p r o v i d e d a d d i t i o n a l f r e e z e f r a c t u r e e v i d e n c e t o s u p p o r t t h i s and t o sugges t t h a t l o s s o f i n t e g r i t y o f the e p i t h e l i a l t i g h t j u n c t i o n s may be the mechanism f o r the i n c r e a s e d p e r m e a b i l i t y . H u l b e r t and a s s o c i a t e s (40) showed t h a t t h i s i n c r e a s e i n p e r m e a b i l i t y i n the g u i n e a p i g i s c o i n c i d e n t w i t h the e x u d a t i v e phase o f the a cu t e i n f l a m m a t o r y r e a c t i o n t h a t f o l l o w s smoke e x p o s u r e . R e a c t i v i t y i n t h e s e a n i m a l s has a l s o been shown t o be i n c r e a s e d f o l l o w i n g c i g a r e t t e smoke e x p o s u r e , b u t o n l y i n the p r e s e n c e o f b e t a - s y m p a t h e t i c and p a r a s y m p a t h e t i c b l o c k a d e ( 4 1 ) . T h i s i n c r e a s e i n r e a c t i v i t y o c c u r s a t the same t ime as does t he p e r m e a b i l i t y i n c r e a s e . Human s t u d i e s o f e p i t h e l i a l p e r m e a b i l i t y and r e a c t i v i t y have a l s o i n d i c a t e d no d i f f e r e n c e i n p e r m e a b i l i t y between s t a b l e a s t h m a t i c s and n o n - a s t h m a t i c s (42) d e s p i t e w i d e l y d i f f e r i n g r e a c t i v i t i e s , a l t h o u g h p e r m e a b i l i t y was enhanced i n n o n - a s t h m a t i c s f o l l o w i n g the i n h a l a t i o n o f h i s t a m i n e . E p i t h e l i a l p e r m e a b i l i t y has been i n v e s t i g a t e d i n c i g a r e t t e smokers by Jones and h i s c o l l e a g u e s (43) and shown t o be e l e v a t e d i n c u r r e n t smokers but r e t u r n i n g toward no rma l w i t h the c e s s a t i o n o f smoking ( 4 4 , 4 5 ) . However , s t u d i e s o f r e a c t i v i t y d i f f e r e n c e s between smokers and non-smokers r e p o r t c o n f l i c t i n g r e s u l t s ( 4 6 , 4 7 , 4 8 , 4 9 , 5 0 ) . Whereas G e r r a r d and a s s o c i a t e s f o u n d symptomat i c smokers t o be more r e a c t i v e than non-smokers ( 4 7 ) , C o c k c r o f t and c o l l e a g u e s (46) have r e c e n t l y r e p o r t e d asymptomat i c young smokers t o be l e s s r e a c t i v e than non-smokers . They s u g g e s t e d t h a t t h i s may be - 118 -due t o a n i c o t i n e - i n d u c e d i n c r e a s e i n c i r c u l a t i n g c a t e c h o l a m i n e s i n the smokers wh i ch r e s u l t s i n a g r e a t e r deg ree o f b e t a - a d r e n e r g i c r e l a x a t i o n o f the a i r w a y s , thus c o u n t e r a c t i n g a p o s s i b l e i n c r e a s e i n r e a c t i v i t y v i a o t h e r mechan isms . I n t r o d u c t i o n t o e x p e r i m e n t s The s t u d i e s r e p o r t e d i n t h i s s e c t i o n were d e s i g n e d t o i n v e s t i g a t e f u r t h e r the h y p o t h e s i s t h a t a i rway h y p e r - r e a c t i v i t y may be r e l a t e d t o enchanced mucosa l p e r m e a b i l i t y . F i r s t , p e r m e a b i l i t y was s t u d i e d i n a g roup o f smokers and non-smokers and compared t o r e a c t i v i t y t o a e r o s o l i z e d h i s t a m i n e w i t h and w i t h o u t p r i o r b e t a - b l o c k a d e t o e l i m i n a t e a p o s s i b l e n i c o t i n e - a s s o c i a t e d e f f e c t on b e t a - a d r e n e r g i c a i rway r e l a x t i o n . S e c o n d , p e r m e a b i l i t y was s t u d i e d i n a g roup o f p a t i e n t s s u s p e c t e d o f h a v i n g o c c u p a t i o n a l l y i n d u c e d asthma as a r e s u l t o f Wes te rn Red Cedar e x p o s u r e . In t h i s g r o u p , p e r m e a b i l i t y was a s s e s s e d b e f o r e and a f t e r c h a l l e n g e w i t h p l i c a t i c a c i d , the a n t i g e n i d e n t i f i e d as r e s p o n s i b l e f o r t h i s fo rm o f a s t h m a t i c r e s p o n s e ( 5 1 ) , and t h i s was r e l a t e d t o r e a c t i v i t y t o i n h a l e d m e t h a c h o l i n e b e f o r e and a f t e r a n t i g e n c h a l l e n g e . The t e c h n i q u e used to measure e p i t h e l i a l p e r m e a b i l i t y i n t h e s e s t u d i e s was t o f o l l o w the d i s a p p e a r a n c e f rom the l u n g and the appea rance i n the b l o o d o f the i n h a l e d t r a c e r , 99m-Technet ium 99m_ D i e t h y l e n t r i a m i n e p e n t a c e t i c a c i d ( T c - D T P A ) . T h i s t r a c e r has been used e x t e n s i v e l y i n r e c e n t y e a r s t o s t udy l u n g e p i t h e l i a l p e r m e a b i l i t y - 119 -i n humans and an ima l s ( 4 2 , 4 3 , 4 4 , 4 5 , 5 2 - 5 6 ) . B e i n g s o l u b l e and o f low m o l e c u l a r w e i g h t , i t i s b e l i e v e d t o be c l e a r e d f rom the l u n g s m a i n l y by d i f f u s i o n a c r o s s the e p i t h e l i u m i n t o the b l o o d s t r e a m ( 5 3 , 5 4 ) . Once i n the b l o o d , i t r a p i d l y d i f f u s e s i n t o the e x t r a v a s c u l a r e x t r a c e l l u l a r f l u i d space and i t s c h i e f r o u t e o f e l i m i n a t i o n i s v i a the k i d n e y s ( 5 7 ) . S i x t y - n i n e p e r c e n t o f an i n j e c t e d dose was r e p o r t e d by McAfee and c o l l e a g u e s (57) t o be e x c r e t e d by the k i d n e y s w i t h a h a l f - l i f e o f 1.73 hours and a f u r t h e r 27% w i t h a t l / 2 o f 9 .23 h o u r s , w i t h o n l y 4% r e m a i n i n g a t 24 h o u r s . Chopra and co-workers (53) s t u d i e d the c l e a r a n c e o f s o l u b l e a e r o s o l s o f d i f f e r e n t m o l e c u l a r we igh t s i n p a t i e n t s w i t h s y s t e m i c s c l e r o s i s and f o u n d i n c r e a s e d p e r m e a b i l i t y compared t o norma l s u b j e c t s f o r b o t h TcO.(MW-163) and Tc-DTPA (MW - 4 9 2 ) . The f a s t e r c l e a r a n c e 4 i n t h e s e p a t i e n t s o f the s m a l l e r m o l e c u l a r we igh t a e r o s o l was b e l i e v e d t o be c o n s i s t e n t w i t h the h y p o t h e s i s t h a t the c l e a r a n c e o f aqueous s o l u t e s t h r o u g h the e p i t h e l i u m i s dependent on m o l e c u l a r s i z e i n r e l a t i o n t o the s i z e o f po res between the e p i t h e l i a l c e l l s . Tc-DTPA p e r m e a b i l i t y i n p a t i e n t s w i t h i n t e r s t i t i a l l u n g d i s e a s e was s t u d i e d by R i n d e r k n e c h t and a s s o c i a t e s (54) and found t o be i n c r e a s e d , bu t t hey f ound no change i n f i v e p a t i e n t s w i t h c h r o n i c o b s t r u c t i v e l u n g d i s e a s e . As d i s c u s s e d above , s e v e r a l s t u d i e s have now been r e p o r t e d i n wh i ch Tc-DTPA has been used t o a s s e s s i n c r e a s e d p e r m e a b i l i t y i n smokers ( 4 3 , 4 4 , 4 5 ) . M o r p h o l o g i c a l and f u n c t i o n a l e v i d e n c e t h a t the p r i n c i p l e b a r r i e r t o c l e a r a n c e o f aqueous s o l u t e s t h r o u g h the a l v e o l a r / c a p i l l a r y - 120 -membrane i s the a l v e o l a r e p i t h e l i u m , has been p r o v i d e d by s t u d i e s (58-62) i n wh i ch the i n t e r e p i t h e l i a l j u n c t i o n s have been shown t o be c o n t i n u o u s z o n u l a e o c c l u d e n t e s . composed o f s e v e r a l s t r a n d s , whereas the e n d o t h e l i a l j u n c t i o n s u s u a l l y c o n t a i n o n l y a s i n g l e s t r a n d w i t h i n t e r m i t t e n t b r e a k s . S chneebe rge r (62) has e s t i m a t e d the e n d o t h e l i a l po re r a d i i t o be 40-58 A and t h a t o f the e p i t h e l i u m , 6-10 A , and c o n c l u d e d t h a t f o r wa te r s o l u b l e m o l e c u l e s up t o a m o l e c u l a r we igh t o f 4 0 , 0 0 0 , the e p i t h e l i u m r e p r e s e n t s the c h i e f d i f f u s i o n b a r r i e r . The i n v e s t i g a t i o n s o f Chop ra ( 5 3 ) , R i n d e r k n e c h t ( 5 4 ) , and Mason (45) have a l l r e p o r t e d i n c r e a s e d c l e a r a n c e f r om the upper zones o f the l u n g i n norma l s u b j e c t s and i n smokers . They have p r o p o s e d t h a t t h i s i s due t o the i n c r e a s e d a l v e o l a r i n f l a t i o n i n the upper l o b e s r e s u l t i n g e i t h e r i n more permeab le i n t e r e p i t h e l i a l j u n c t i o n s , due t o s t r e t c h , o r an i n c r e a s e i n the r a t i o o f s u r f a c e a r e a t o the volume o f f l u i d c o n t a i n i n g the t r a c e r . S i m i l a r i n c r e a s e s i n s o l u t e p e r m e a b i l i t y i n e x p e r i m e n t a l an ima l s have been seen when the l u n g i s i n f l a t e d w i t h f l u i d (63) o r w i t h a i r ( 6 4 ) . These f i n d i n g s , t o g e t h e r w i t h the o b s e r v a t i o n t h a t r e g i o n a l p e r m e a b i l i t y d i f f e r e n c e s a re l o s t when p o s i t i v e e n d - e x p i r a t o r y p r e s s u r e (PEEP) i s a p p l i e d a f t e r the i n h a l a t i o n o f the t r a c e r ( t o e l i m i n a t e r e g i o n a l d i f f e r e n c e s i n a l v e o l a r i n f l a t i o n ) (54) l e n d s u p p o r t to t he c o n c e p t t h a t the g r e a t e r i n f l a t i o n i n the upper l o b e s i s r e s p o n s i b l e f o r the i n c r e a s e d c l e a r a n c e . In summary, i t i s g e n e r a l l y b e l i e v e d t h a t the d i s a p p e a r a n c e 99M_ o f T c - D T P A f r om the l u n g a f t e r i n h a l a t i o n i s an i n d i c a t o r o f the - 121 -p e r m e a b i l i t y o f the pu lmonary e p i t h e l i u m . A l t h o u g h most s t u d i e s have f o c u s s e d on a l v e o l a r c l e a r a n c e , E lwood and c o l l e a g u e s (42) and O b e r d o r s t e r and co-workers (55) have used i t s u c c e s s f u l l y t o s t u d y a i rway e p i t h e l i a l p e r m e a b i l i t y as w e l l . M e t h o d s : S tudy 1: P e r m e a b i l i t y and R e a c t i v i t y i n Smokers and Non-Smokers S u b j e c t s Ten asymptomat i c smokers , (mean age 3 2 . 4 + 6 .4 y e a r s ) who smoked a t l e a s t 20 c i g a r e t t e s / d a y (mean pack y e a r s 17 .2 + 7.6) were s t u d i e d . One s u b j e c t was a t o p i c . E i g h t a s ymptoma t i c , non-smok ing , n o n - a t o p i c m e d i c a l and l a b o r a t o r y p e r s o n n e l s e r v e d as c o n t r o l s (mean age 31 .1 + 7.3 y e a r s ) . A l l s u b j e c t s d e n i e d r e c e n t upper r e s p i r a t o r y t r a c t i n f e c t i o n and p r o v i d e d w r i t t e n c o n s e n t a f t e r the aims and p r o c e d u r e s o f the s t udy had been e x p l a i n e d t o them. Pu lmonary F u n c t i o n T e s t s Pu lmonary f u n c t i o n t e s t i n g was pe r f o rmed on each s u b j e c t u s i n g a volume d i s p l a c e m e n t body p l e t h y s i n o g r a p h . Volume was measured w i t h a Krogh s p i r o m e t e r e q u i p p e d w i t h a S h a e v i t z l i n e a r d i s p l a c e m e n t t r a n s d u c e r ; f l o w was measured w i t h a F l e i s c h No .3 pneumotachograph c o u p l e d t o a Sanborn 270 p r e s s u r e t r a n s d u c e r , and p r e s s u r e was measured w i t h a V a l i d y n e 45-MP d i f f e r e n t i a l p r e s s u r e t r a n s d u c e r . i - 122 -F u n c t i o n a l r e s i d u a l c a p a c i t y ( F R O was measured by B o y l e ' s Law t e c h n i q u e (65) and r e s i d u a l volume (RV) and t o t a l l u n g c a p a c i t y (TLC) were c a l c u l a t e d . Maximum e x p i r a t o r y maneuvers were p e r f o r m e d and f l o w and vo lume s i g n a l s were d i g i t i z e d t o an a c c u r a c y o f 0 . 4% and f e d t o an A p p l e I I c ompu te r , programmed t o c a l c u l a t e volume i n the f i r s t s e cond o f f o r c e d e x p i r a t i o n (FEV^) and maximum f l o w a t 50% f o r c e d v i t a l c a p a c i t y ( v JQ ) • N i t r o g e n c o n c e n t r a t i o n o f e x p i r e d a i r , f o l l o w i n g a s i n g l e maximal i n s p i r a t i o n o f 0^, was measured by a N^ a n a l y z e r and the s i g n a l was d i g i t i z e d and d i s p l a y e d a g a i n s t volume on the A p p l e computer f o r c a l c u l a t i o n o f the s l o p e o f phase I I I o f the n i t r o g e n washout c u r v e ( a ^ / l ) , c l o s i n g volume (CV) and c l o s i n g c a p a c i t y (CC) . FEV^ and were e x p r e s s e d as p e r c e n t p r e d i c t e d based on the p r e d i c t i o n f o r m u l a s o f M o r r i s e t a l ( 6 6 ) . A N^/l and CC/TLC were e x p r e s s e d as p e r c e n t p r e d i c t e d based on the p r e d i c t i o n f o r m u l a s o f B u i s t and Ross ( 6 7 , 6 8 ) . D e t e r m i n a t i o n o f P e r m e a b i l i t y A i rway e p i t h e l i a l p e r m e a b i l i t y was a s s e s s e d u s i n g an a e r o s o l o f t e c h n e t i u m - l a b e l l e d d i e t h y l e n e t r i a m i n e p e n t a c e t i c a c i d 99nv_ ( i c-DTPA ) as a t r a c e r . The a e r o s o l was g e n e r a t e d u s i n g a D e V i l b i s s 2.101 u l t r a s o n i c n e b u l i z e r c o n t a i n i n g 2.5 mCi ^ \" \" T c - D T P A i n 10 ml no rma l s a l i n e . T h i s n e b u l i z e r has a maximum o u t p u t o f 3 ml/min and g e n e r a t e s d r o p l e t s w i t h a mean mass ae rodynamic d i a m e t e r o f 6.3 m i c r o n s ( 6 9 ) . S u b j e c t s i n h a l e d f rom a mou thp i e ce w i t h nose c l i p s i n p l a c e . - 123 -Immed ia te l y a f t e r a 2 m inu te i n h a l a t i o n o f the t r a c e r , s u b j e c t s were p o s i t i o n e d under a Siemens PHO/gamma LFOV s c i n t i l l a t i o n camera l i n k e d t o a PDP/11 compute r . C o n t i n u o u s coun t s were t aken o v e r the c h e s t and r e c o r d e d e v e r y 30 seconds f o r t h i r t y m inu tes and a r e g i o n o f i n t e r e s t c o r r e s p o n d i n g to the l u n g s and t r a c h e a was s u b s e q u e n t l y a n a l y s e d . C o r r e c t i o n s were made f o r d e c a y , backg round r a d i o a c t i v i t y , and r a d i o a c t i v i t y i n the h e a r t and pu lmonary v a s c u l a t u r e by the method d e s c r i b e d by E lwood and a s s o c i a t e s ( 4 2 ) . The d i s a p p e a r a n c e o f t r a c e r f rom the l u n g f i e l d s f i t the e x p o n e n t i a l —Bx e q u a t i o n y = Ae (mean r = . 9 6 , non smoke rs ; . 9 8 , smokers) i n wh i ch y = c o u n t s / m i n . i n the l u n g , x = t i m e , A = CPM a t t ime 0 , and B i s a c o n s t a n t wh i ch d e s c r i b e s the shape o f the c u r v e and i s used to c a l c u l a t e the r a t e o f d e c r e a s e o f l u n g a c t i v i t y o ve r t i m e . Fo r each s u b j e c t , a l u n g h a l f - l i f e was d e t e r m i n e d by e x t r a p o l a t i o n f r om the d i s a p p e a r a n c e c u r v e as the p o i n t a t wh i ch 50% o f i n i t i a l a c t i v i t y wou ld rema in i n the l u n g s ( i . e . y = . 5 A ) , and the d e c r e a s e i n l u n g a c t i v i t y pe r m inu te was c a l c u l a t e d a c c o r d i n g t o the f o r m u l a l - e B . S e r i a l 2 m l . venous b l o o d samples were t aken v i a a h e p a r i n i z e d i n d w e l l i n g #21 b u t t e r f l y a t 7, 1 0 , 1 5 , 2 0 , 2 5 , 3 0 , 4 0 , 50 and 60 m inu tes a f t e r the s t a r t o f a e r o s o l d e l i v e r y . These were c o u n t e d i n a Beckman Gamma 7000 gamma c o u n t e r . A p e r m e a b i l i t y i ndex was c a l c u l a t e d f o r each t ime p e r i o d i n wh i ch b l o o d was drawn, a c c o r d i n g t o the f o l l o w i n g f o r m u l a : CPM i n 1 m l . b l o o d X body wt . ( kg . ) P e r m e a b i l i t y Index = camera CPM o v e r l u n g f i e l d s a t t ime z e r o - 124 -To a s s e s s the r e l a t i v e d i s t r i b u t i o n o f the l a b e l f o r each s u b j e c t , ave rage gamma camera c o u n t s f o r the f i r s t 2 m inu tes f o l l o w i n g a e r o s o l d e l i v e r y were c a l c u l a t e d f o r e q u a l s i z e d r e g i o n s o f i n t e r e s t c o r r e s p o n d i n g t o c e n t r a l a i rways and l u n g p e r i p h e r y and the r a t i o o f c e n t r a l t o p e r i p h e r a l d e p o s i t i o n was d e t e r m i n e d . Assessment o f B r o n c h i a l R e a c t i v i t y B r o n c h i a l r e a c t i v i t y was d e t e r m i n e d i n 17 o f the 18 s u b j e c t s u s i n g a m o d i f i c a t i o n o f t he method o f C o c k c r o f t and a s s o c i a t e s ( 8 , 7 0 ) . H i s t a m i n e d i h y d r o c h l o r i d e a t d o u b l i n g doses f rom 4 mg/ml ( o f the s a l t ) t o a maximum o f 64 mg/ml was d e l i v e r e d u s i n g a Benne t t -Tw in n e b u l i z e r ( o u t p u t 0 .25 ml/min) a t an oxygen f l o w r a t e o f 5 l . / m i n . f o r 2 m i n . On a s e p a r a t e o c c a s i o n , a second assessment o f r e a c t i v i t y was o b t a i n e d f o r 16 o f the 17 s u b j e c t s . On t h i s o c c a s i o n h i s t a m i n e exposu re was p r e c e d e d by a e r o s o l a d m i n i s t r a t i o n o f p r o p r a n o l o l a t a c o n c e n t r a t i o n o f 15 mg/ml n e b u l i z e d f o r 4 m i n u t e s . H i s t a m i n e d o s e - r e s p o n s e c u r v e s were c o n s t r u c t e d f o r each i n d i v i d u a l by p l o t t i n g the p e r c e n t a g e d e c r e a s e i n FEV^ f r om p r e - h i s t a m i n e l e v e l s a g a i n s t the l o g o f the h i s t a m i n e d o s e . F o r the FEV^ r e s p o n s e a f t e r b e t a - b l o c k a d e , the c o n t r o l FEV^ u s e d was t h a t o b t a i n e d a f t e r the p r o p r a n o l o l a e r o s o l bu t b e f o r e h i s t a m i n e . F o l l o w i n g b o t h h i s t a m i n e c h a l l e n g e s e s s i o n s , e l e v e n s u b j e c t s were g i v e n a e r o s o l s a l b u t a m o l ( a l b u t e r o l ) and FEV^ was r e c o r d e d a t 10 m inu te s p o s t b r o n c h o d i l a t o r . By 10 m inu te s a l l s u b j e c t s were a t o r v e r y nea r p r e - h i s t a m i n e l e v e l s f o r FEV^ when no p r o p r a n o l o l was g i v e n . However , when h i s t a m i n e was p r e c e d e d by p r o p r a n o l o l , the FEV^, r e c o r d e d a t 10 m i n u t e s p o s t b r o n c h o d i l a t o r , showed o n l y s l i g h t o r modera te improvement , i n d i c a t i n g - 125 -p e r s i s t a n t b e t a - a d r e n e r g i c b l o c k a d e . F o r b o t h h i s t a m i n e c h a l l e n g e s , the dose r e q u i r e d t o cause a 20% d e c r e a s e i n FEV^ (PC^Q) was c a l c u l a t e d by l i n e a r i n t e r p o l a t i o n between the l a s t two p o i n t s on the h i s t a m i n e dose r e s p o n s e c u r v e . T h i s c a l c u l a t i o n was no t p o s s i b l e f o r a l l s u b j e c t s s i n c e s e v e r a l f a i l e d t o show a 20% d e c r e a s e i n FEV^. T h e r e f o r e , i n a d d i t i o n t o the c a l c u l a t i o n o f P C 2 Q » a r e a c t i v i t y i ndex (RI) was a l s o c a l c u l a t e d as f o l l o w s : maximum p e r c e n t a g e d e c r e a s e i n FEV^ l o g [ h i s t a m i n e ] a s s o c i a t e d w i t h t h i s FEV^ d e c r e a s e T h i s c a l c u l a t i o n p r o v i d e d a n u m e r i c a l assessment o f the h i g h end o f the h i s t a m i n e d o s e - r e s p o n s e cu r ve and made i t p o s s i b l e t o compare smokers t o non-smokers , and t o compare i n d i v i d u a l s u b j e c t s b e f o r e and a f t e r b e t a -b l o c k a d e . The d i f f e r e n c e between the RI w i t h o u t p r o p r a n o l o l and t h a t w i t h p r o p r a n o l o l , we te rmed the A RI• Da ta A n a l y s i s Mean v a l u e s f o r pu lmonary f u n c t i o n v a r i a b l e s , l u n g h a l f - l i f e o f 99nv_ Tc-DTPA , and the r e a c t i v i t y index (w i th and w i t h o u t b e t a - b l o c k a d e ) , were compared f o r smokers and non-smokers u s i n g S t u d e n t s u n p a i r e d t - t e s t . P e r m e a b i l i t y i n d i c e s f o r a l l t ime p e r i o d s were compared f o r smokers and non-smokers u s i n g 2-way a n a l y s i s o f v a r i a n c e . P a i r e d t - t e s t s were used t o compare the r e a c t i v i t y i ndex w i t h o u t b e t a - b l o c k a d e t o t h a t a f t e r b e t a - b l o c k a d e w i t h i n the two s u b j e c t s g r o u p s . P o s s i b l e r e l a t i o n s h i p s between p e r m e a b i l i t y , r e a c t i v i t y and pu lmonary f u n c t i o n v a r i a b l e s i n the two groups t o g e t h e r and s e p a r a t e l y were d e t e r m i n e d by l i n e a r r e g r e s s i o n a n a l y s i s . - 126 -S tudy 2: P e r m e a b i l i t y and R e a c t i v i t y b e f o r e and a f t e r p l i c a t i c a c i d c h a l l e n g e . S u b j e c t s N ine p a t i e n t s r e f e r r e d t o the Vancouve r G e n e r a l H o s p i t a l O c c u p a t i o n a l R e s p i r a t o r y D i s e a s e U n i t f o r assessment o f p o s s i b l e Weste rn Red Ceda r asthma were s t u d i e d . T h e i r ages r anged f r om 22 t o 63 y e a r s (mean 4 7 . 0 + 1 5 . 6 ) . F i v e were l i f e t i m e non-smokers and the o t h e r f o u r were ex-smoke r s . I n f o r m e d , w r i t t e n c o n s e n t was o b t a i n e d f rom a l l p a t i e n t s . P e r m e a b i l i t y P e r m e a b i l i t y was a s s e s s e d , as d e s c r i b e d above f o r the smoking s t u d y , on the morn ing o f day 1, and then r e p e a t e d on the morn ing o f day 3, a p p r o x i m a t e l y 24 hours a f t e r p l i c a t i c a c i d c h a l l e n g e . P r i o r t o the second p e r m e a b i l i t y s t udy on day 3, c o n t r o l b l o o d samples were t aken and s c a n n i n g 99m_ p e r f o r m e d ove r the l u n g f i e l d s t o i n s u r e t h a t t h e r e was no r e s i d u a l T C a c t i v i t y i n the l u n g s o r b l o o d . Pu lmonary F u n c t i o n , M e t h a c h o l i n e C h a l l e n g e , A n t i g e n C h a l l e n g e On the a f t e r n o o n o f day 1, pu lmonary f u n c t i o n t e s t i n g and m e t h a c h o l i n e c h a l l e n g e f o r assessment o f n o n - s p e c i f i c a i rways r e a c t i v i t y were c a r r i e d ou t by the s t a f f o f the O c c u p a t i o n a l R e s p i r a t o r y D i s e a s e U n i t a t VGH. A P C 2 Q f o r m e t h a c h o l i n e was d e t e r m i n e d i n a s i m i l a r manner t o t h a t o f C o c k c r o f t and co-workers ( 7 0 ) . B r i e f l y t h i s i n v o l v e d a e r o s o l i n h a l a t i o n o f g r a d e d doses o f m e t h a c h o l i n e (up t o a maximum o f 16 mg/ml) and measurement o f the subsequen t change i n FEV^ i n the same f a s h i o n as d e s c r i b e d above f o r the h i s t a m i n e c h a l l e n g e . - 127 -P l i c a t i c a c i d i n h a l a t i o n c h a l l e n g e was p e r f o r m e d by the VGH g roup on the morn ing o f day 2 and the r e s p o n s e was m o n i t o r e d t h r o u g h o u t the day and d u r i n g the e v e n i n g by means o f s p i r o g r a p h i c measurements o f FEV^ and measurement o f peak f l o w w i t h a W r i g h t ' s peak f l o w m e t e r . The d e t a i l s o f t h e s e p r o c e d u r e s have been d e s c r i b e d p r e v i o u s l y ( 8 ) . F o l l o w i n g the second p e r m e a b i l i t y assessment on day 3, a r e p e a t m e t h a c h o l i n e c h a l l e n g e was p e r f o r m e d . Da t a A n a l y s i s S t u d e n t ' s t - t e s t was used t o compare FEV^ and t l / 2 v a l u e s between S tudy 1 and S tudy 2 s u b j e c t s , and t l / 2 b e f o r e and a f t e r a n t i g e n c h a l l e n g e . Two-way a n a l y s i s o f v a r i a n c e was used t o a s s e s s p o s s i b l e d i f f e r e n c e s i n the p e r m e a b i l i t y i n d i c e s a t a l l t ime p o i n t s , b e f o r e and a f t e r c h a l l e n g e . - 128 -R e s u l t s S tudy 1: Smokers vs Non-smokers I n d i v i d u a l s u b j e c t d a t a and pu lmonary f u n c t i o n t e s t r e s u l t s a r e shown i n T a b l e I I I ( p . 1 6 1 ) . The FEV^/FVC r a t i o was the same f o r smokers and non-smokers bu t t h e r e were s i g n i f i c a n t d i f f e r e n c e s between the two g roups f o r A N ^ / l , c l o s i n g c a p a c i t y , and the maximum f l o w r a t e a t 50% v i t a l c a p a c i t y ( v^Q) ( p < . 0 . 0 5 ) , w i t h the smokers h a v i n g compromised l u n g f u n c t i o n . P e r m e a b i l i t y The p a t t e r n o f a e r o s o l d e p o s i t i o n i s shown i n F i g u r e 8 ( p . 1 5 6 ) . The mean r a t i o o f CPM i n c e n t r a l t o p e r i p h e r a l r e g i o n s was i d e n t i c a l f o r the two groups (non-smokers : 1.18 + 0 . 1 7 ; smokers : 1.19 + 0 . 1 5 ) . F i g u r e 9 (p .157 ) 99m_ shows the d i s a p p e a r a n c e o f the Tc-DTPA t r a c e r f rom the l u n g f i e l d s o v e r t i m e . The l u n g h a l f - l i f e and d i s a p p e a r a n c e r a t e f o r each s u b j e c t i s shown i n T a b l e IV ( p . 1 6 2 ) . The non-smoking g roup had a mean h a l f - l i f e i n the l u n g o f 110 .0 + 6 2 . 7 min and a mean d i s a p p e a r a n c e r a t e o f 0 .90 + 0 .54 p e r c e n t p e r m i n u t e . The smoking g roup had a s i g n i f i c a n t l y l ower mean h a l f - l i f e o f 4 2 . 4 + 1 6 . 8 min and a f a s t e r mean d i s a p p e a r a n c e r a t e o f 2.12 + 0 .84 p e r c e n t p e r m inu te ( p < 0 . 0 0 5 ) . F i g u r e 10 (p .158 ) shows the appearance o f the t r a c e r i n the b l o o d o v e r t i m e . The appearance r a t e i s i n c r e a s e d i n smokers compared t o non-smokers . I n d i v i d u a l p e r m e a b i l i t y i n d i c e s a t 1 0 , 25 and 60 m inu tes a re shown i n T a b l e IV ( p . 1 6 2 ) . Mean v a l u e s a t a l l t ime p e r i o d s were s i g n i f i c a n t l y h i g h e r f o r smokers than f o r non-smokers ( p<0 .001 ) . - 129 -R e a c t i v i t y H i s t a m i n e dose r e s p o n s e c u r v e s f o r each s u b j e c t , w i t h and w i t h o u t p r i o r p r o p r a n o l o l t r e a t m e n t , a r e shown i n F i g u r e 11 (p .159) : . I n d i v i d u a l r e s u l t s f o r P C 2 Q and f o r the r e a c t i v i t y i ndex (w i th and w i t h o u t p r o p r a n o l o l ) a r e shown i n T a b l e IV ( p . 1 6 2 ) . The mean r e a c t i v i t y i ndex w i t h o u t b e t a - b l o c k a d e , was 1 1 . 8 + 5.3 f o r non-smokers and 1 2 . 0 + 8 .0 f o r smokers . A f t e r b e t a - b l o c k a d e , r e a c t i v i t y was a g a i n s i m i l a r between the two g r o u p s , bu t had i n c r e a s e d , r e s u l t i n g i n a r e a c t i v i t y i ndex o f 17 .6 + 7.0% f o r non-smokers and 19 .4 + 1 3 . 9 % f o r smokers . Ten s u b j e c t s (5 non-smokers and 5 smokers) showed a c l e a r i n c r e a s e i n r e a c t i v i t y and a d e c r e a s e o c c u r r e d i n o n l y one c a s e . T h i s i n c r e a s e was s i g n i f i c a n t (p<0.001) but h i g h l y v a r i a b l e , and o f the same magn i tude i n b o t h g r o u p s . The re was no s i g n i f i c a n t c o r r e l a t i o n between the r e a c t i v i t y i n d e x , 99m_ w i t h o r w i t h o u t b e t a - b l o c k a d e , and l u n g h a l f - l i f e o f T c-DTPA , p e r m e a b i l i t y i n d i c e s , o r any o f the pu lmonary f u n c t i o n t e s t s p e r f o r m e d . - 130 -S tudy 2: B e f o r e and a f t e r a n t i g e n c h a l l e n g e T a b l e V (p .163 ) shows the mean v a l u e s f o r age , b a s e l i n e FEV^, and PC^Q t o m e t h a c h o l i n e b e f o r e and a f t e r a n t i g e n c h a l l e n g e , i n the f o u r s u b j e c t s who r e s p o n d e d t o p l i c a t i c a c i d c h a l l e n g e and i n the f i v e who d i d no t r e s p o n d . (A p o s i t i v e r e s p o n s e t o p l i c a t i c a c i d was d e t e r m i n e d f rom the measurements o f FEV^ and peak f l o w a f t e r c h a l l e n g e ) . The mean p r e - c h a l l e n g e FEV^ f o r the n i n e s u b j e c t s was 7 9 . 9 % p r e d i c t e d wh i ch was s i g n i f i c a n t l y l ower than t h a t o f the s u b j e c t s i n the f i r s t s t u d y . In t h r e e o f the f o u r s u b j e c t s who r e sponded to the p l i c a t i c a c i d c h a l l e n g e the r e s p o n s e was b o t h immediate and l a t e , and i n the f o u r t h , o n l y a l a t e r e s p o n s e was s e e n . The P C 2 Q t o m e t h a c h o l i n e f o l l o w i n g a n t i g e n c h a l l e n g e d e c r e a s e d i n t h r e e o f the f o u r p l i c a t i c a c i d r e s p o n d e r s and i n one o f the n o n - r e s p o n d e r s . P e r m e a b i l i t y d a t a b e f o r e and a f t e r a n t i g e n c h a l l e n g e i s shown i n T a b l e V I (p 1 6 3 ) . Compar i son o f a n t i g e n r e s p o n d e r s t o n o n - r e s p o n d e r s r e v e a l e d no s i g n i f i c a n t d i f f e r e n c e between t h o s e g roups f o r the p e r m e a b i l i t y v a r i a b l e s e i t h e r b e f o r e o r a f t e r p l i c a t i c a c i d c h a l l e n g e . The t l / 2 and P I ^ f ° r r e s p o n d e r s b e f o r e a n t i g e n c h a l l e n g e were 59 .4 min and 10 .6 r e s p e c t i v e l y , compared t o 55 .1 min and 1 4 . 3 f o r n o n - r e s p o n d e r s . The c o r r e s p o n d i n g f i g u r e s a f t e r c h a l l e n g e were 7 1 . 0 min and 8.4 f o r r e s p o n d e r s and 72 .0 min and 1 1 . 8 f o r n o n - r e s p o n d e r s . These d a t a d o , however , r e v e a l a s i g n i f i c a n t i n c r e a s e i n t l / 2 f r om the b e f o r e c h a l l e n g e t o a f t e r c h a l l e n g e p e r m e a b i l i t y s t u d i e s f o r the n o n - r e s p o n d e r s and f o r the g roup as a whole ( 56 .9 m i n . b e f o r e c h a l l e n g e compared t o 71 .5 min a f t e r c h a l l e n g e ) ( p < . 0 1 ) and a t r e n d toward the same i n - 131 -the r e s p o n d e r s . No concommitant d e c r e a s e i n the p e r m e a b i l i t y i n d i c e s was seen i n e i t h e r g r o u p , however . F i n a l l y the t l / 2 f o r the whole g roup b e f o r e c h a l l e n g e ( 56 .9 + 1 8 . 6 min) was s i g n i f i c a n t l y l ower than t h a t o f the non-smokers i n S tudy 1 ( 110 .0 + 62 .7 min) and h i g h e r than t h a t o f the smokers (42 .4 + 1 6 . 8 min) ( p < 0 . 5 ) , a l t h o u g h t h e r e was no d i f f e r e n c e i n p e r m e a b i l i t y i n d i c e s between t h o s e n i n e s u b j e c t s and the non-smokers i n the f i r s t s t u d y . S u b j e c t i v e assessment o f the gamma camera images a f t e r ^ \" T C - D T P A i n h a l a t i o n r e v e a l e d more v a r i a b i l i t y i n the d e p o s i t i o n p a t t e r n i n t h e s e s u b j e c t s compared t o t h o s e i n S tudy 1, w i t h d e p o s i t i o n b e i n g more c e n t r a l i n a l l bu t one o f t h e s e s u b j e c t s . Compar i son o f p r e - and p o s t - c h a l l e n g e d e p o s i t i o n o f the t r a c e r r e v e a l e d no change i n any o f the non- re sponde r s and s l i g h t l y more p e r i p h e r a l p e n e t r a t i o n o f the t r a c e r a f t e r c h a l l e n g e i n t h r e e o f the f o u r r e s p o n d e r s w i t h the o p p o s i t e p a t t e r n i n the r e m a i n i n g r e s p o n d e r ( see F i g u r e 12 p . 1 6 0 ) . - 132 -DISCUSSION T h i s s t udy was d e s i g n e d t o t e s t the h y p o t h e s i s t h a t h y p e r r e a c t i v i t y o f the a i rways may be r e l a t e d t o an i n c r e a s e i n a i rways p e r m e a b i l i t y as a r e s u l t o f mucosa l damage e i t h e r by c i g a r e t t e smoke o r a n t i g e n c h a l l e n g e . A l t h o u g h a s i g n i f i c a n t d i f f e r e n c e i n p e r m e a b i l i t y between smokers and non-smokers was f o u n d , t h e r e was no c o r r e l a t i o n between t h i s and r e a c t i v i t y . F u r t h e r m o r e , d e s p i t e e l e v a t e d r e a c t i v i t y i n b o t h smokers and non-smokers f o l l o w i n g p r o p r a n o l o l a e r o s o l , t h e s e g roups were s t i l l i d e n t i c a l w i t h r e s p e c t t o r e a c t i v i t y and t h i s i n c r e a s e d r e a c t i v i t y bo re no r e l a t i o n t o p e r m e a b i l i t y . F i n a l l y , p e r m e a b i l i t y i n the t h r e e p a t i e n t s who r e s p o n d e d t o p l i c a t i c a c i d c h a l l e n g e d i d no t i n c r e a s e a f t e r a n t i g e n c h a l l e n g e , d e s p i t e the f a c t t h a t n o n - s p e c i f i c r e a c t i v i t y was e l e v a t e d i n the p a t i e n t s a f t e r the a n t i g e n e x p o s u r e . Smokers v e r s u s Non-smokers The o b s e r v e d p e r m e a b i l i t y d i f f e r e n c e between the smokers and non-smokers i n the f i r s t p a r t o f t h i s s t udy most l i k e l y r e f l e c t s an a l t e r a t i o n i n the e p i t h e l i u m o f the smokers such t h a t the t r a c e r can d i f f u s e more r e a d i l y f rom the l u n g s i n t o the b l o o d ( 3 9 , 4 0 ) . These r e s u l t s c o r r e s p o n d w i t h t h o s e o f Jones and h i s c o l l e a g u e s (43) who have r e p o r t e d i n c r e a s e d a l v e o l a r p e r m e a b i l i t y t o T c ^ m - D T P A i n smokers compared t o non-smokers . T h e r e a r e , however , o t h e r f a c t o r s i n t h i s s t udy wh i ch c o u l d a f f e c t the d i s a p p e a r a n c e o f the t r a c e r f rom the l u n g s o r i t s appearance i n the b l o o d , and c o u l d c o n c e i v a b l y a c coun t f o r the d i f f e r e n c e seen between smokers and non-smokers . These a r e : 1) d i f f e r i n g m u c o - c i l i a r y c l e a r a n c e r a t e s ; 2) - 133 -v a r i a t i o n s i n the a r e a o f i n i t i a l d e p o s i t i o n o f the t r a c e r ; 3) a l t e r e d p e r f u s i o n o f the l u n g s ; and 4) d i f f e r e n c e s i n the volume o f d i s t r i b u t i o n o r r a t e o f r emova l o f the t r a c e r once i t r e a c h e s the b l o o d s t r e a m . M u c o - c i l i a r y c l e a r a n c e o f the t r a c e r s o l u t i o n wou ld r e s u l t i n a measu r ab l e d i s a p p e a r a n c e o f the t r a c e r f rom the l u n g and c o n f o u n d the d i s a p p e a r a n c e d i r e c t l y i n t o the b l o o d s t r e a m . However , the r a t e o f d i s a p p e a r a n c e seen i n t h i s s t udy i s much f a s t e r than c o u l d be a c c o u n t e d f o r by m u c o - c i l i a r y c l e a r a n c e a l o n e . S a n c h i s and a s s o c i a t e s (71) s t u d i e d the c l e a r a n c e o f an a e r o s o l o f human serum a lbumin w i t h d r o p l e t s o f mass median ae rodynamic d i a m e t e r (MMAD) o f 3u and f o u n d the h a l f - l i f e f o r the whole l u n g t o be 2 3 . 0 h r . The a e r o s o l u sed i n t h i s s t udy had a MMAD o f 6 . 3 u , however , t h i s d i f f e r e n c e i n MMAD w o u l d , a c c o r d i n g to the Task. Group on Lung Dynamics o f the ICRP ( 7 2 ) , r e s u l t i n a g r e a t e r degree o f n a s o p h a r y n g e a l d e p o s i t i o n but no t a g r e a t e r d i f f e r e n c e i n the r e l a t i v e d e p o s i t i o n i n pu lmonary t r a c h e o - b r o n c h i a l r e g i o n s o f the l u n g . In a d d i t i o n the l o n g l e n g t h and a n g l e d shape o f the t u b i n g used i n the a e r o s o l d e l i v e r y s ys tem wou ld t end t o r educe the number o f l a r g e r p a r t i c l e s i n the a e r o s o l s t r eam by i m p a c t i o n on the w a l l s o f the t u b i n g and by e v a p o r a t i o n . T h i s c o u l d a c coun t f o r the o b s e r v e d d e p o s i t i o n p a t t e r n i n the f i r s t s t udy ( F i g u r e 8) wh i ch appea rs t o be t h r o u g h o u t the t r a c h e o - b r o n c h i a l t r e e and i n the l u n g p e r i p h e r y . T r a c e r d e p o s i t e d a t t h i s l e v e l i n the l u n g s wou ld no t be s o l e l y c l e a r e d by the m u c o - c i l i a r y e s c a l a t o r w i t h the h a l f - l i f e o b s e r v e d i n t h i s s t u d y . D i f f u s i o n i n t o the b l o o d s t r e a m must be the main r o u t e f o r the d i s a p p e a r a n c e o f the t r a c e r f rom the l u n g s . T h i s i s f u r t h e r borne ou t by the p o s i t i v e c o r r e l a t i o n seen between the l u n g h a l f - l i f e and the b l o o d l e v e l s o f the t r a c e r as measured by the p e r m e a b i l i t y - 134 -i n d i c e s (R = . 5 7 ) . M u c o - c i l i a r y c l e a r a n c e f rom the l a r g e r a i rways d o e s , however , o c c u r r a p i d l y and c o u l d c o n c e i v a b l y a c coun t f o r the a l t e r e d d i s a p p e a r a n c e seen i n the smokers i f m u c o - c i l i a r y c l e a r a n c e was i n c r e a s e d i n the smoking g r o u p . S t u d i e s i n wh i ch m u c o - c i l i a r y t r a n s p o r t r a t e s have been compared between smokers and non-smokers , however , show e i t h e r no e f f e c t (73) o r i m p a i r e d c l e a r a n c e (74) i n smokers , and the d a t a shows no i n c r e a s e i n c e n t r a l d e p o s i t i o n i n the smoke r s . More p e r i p h e r a l d e p o s i t i o n o f the t r a c e r i n the smokers , and t h e r e f o r e a g r e a t e r s u r f a c e a r e a a v a i l a b l e f o r d i f f u s i o n , c o u l d a l s o r e s u l t i n i n c r e a s e d t r a n s f e r a c r o s s the e p i t h e l i u m . Jones and c o l l e a g u e s ( 4 3 ) , who used t e c h n i q u e s t o a c h i e v e s m a l l e r p a r t i c l e s i z e and c o n s e q u e n t l y d e p o s i t e d the a e r o s o l m a i n l y i n a l v e o l i , f ound a mean h a l f - l i f e o f the t r a c e r i n non-smokers o f 50 min and i n smokers o f 20 m i n . T h i s i s a p p r o x i m a t e l y t w i c e the r a t e seen i n t h i s s t u d y . S i m i l a r l y , R i n d e r k n e c h t and a s s o c i a t e s (54) who a l s o had p r e d o m i n a n t l y p e r i p h e r a l d e p o s i t i o n , f ound a h i g h e r r a t e o f d i s a p p e a r a n c e i n t h e i r norma l s u b j e c t s (mean 1.56%/min compared t o 0 . 9 % / m i n ) , and O b e r d o r s t e r and h i s c o l l e a g u e s (55) showed a h a l f - l i f e o f 72 m inu te s when t e c h n i q u e s were used t o d e p o s i t the a e r o s o l m a i n l y i n c o n d u c t i n g a i rways and 43 m inu te s when d e p o s i t i o n was m a i n l y a l v e o l a r . However, i t has been s u g g e s t e d t h a t smokers w o u l d , i f a n y t h i n g , t e n d to have more c e n t r a l d e p o s i t i o n than non-smokers (75) a nd , i n t h i s s t u d y , the r e l a t i v e r a t i o s o f c e n t r a l t o p e r i p h e r a l d e p o s i t i o n i n smokers and non-smokers were i d e n t i c a l . T h u s , i t i s u n l i k e l y t h a t d i f f e r e n c e s i n s u r f a c e a r e a o f d e p o s i t i o n a re r e s p o n s i b l e f o r the e l e v a t e d r a t e o f t r a n s f e r o f the t r a c e r i n t o the b l o o d i n smoke r s . - 135 -G r e a t e r p e r f u s i o n i n the l u n g s o f the smokers i s an u n l i k e l y cause o f an e l e v a t e d d i s a p p e a r a n c e r a t e because i t has been shown t h a t p e r f u s i o n -l i m i t a t i o n i s o n l y s i g n i f i c a n t f o r gases t h a t a r e h i g h l y s o l u b l e i n the b l o o d ( 7 6 ) . T h i s has r e c e n t l y been c o n f i r m e d by R i z k and h i s c o l l e a g u e s ( 7 7 ) , s t u d y i n g p e r m e a b i l i t y t o Tc-DTPA i n d o g s , who d i v e r t e d the whole o f the c a r d i a c o u t p u t t h r o u g h one l u n g , and found no i n c r e a s e i n p e r m e a b i l i t y . F i n a l l y , i t i s p o s s i b l e t h a t the measured appearance o f the Tc-DTPA i n the b l o o d i s e l e v a t e d i n the smokers as a r e s u l t o f a l t e r a t i o n s i n the volume o f d i s t r i b u t i o n o r d e l a y e d remova l o f the t r a c e r f rom the b l o o d . The a c t u a l volume o f d i s t r i b u t i o n c o u l d have been measured i n each c a se by i n j e c t i n g DTPA t agged w i t h a d i f f e r e n t l a b e l , as d i d Huchon e t a l ( 5 2 ) , bu t t h i s was no t done because o f the i n c r e a s e d r a d i a t i o n i n v o l v e d . I n s t e a d , i t was d e c i d e d t o p a r t l y c o n t r o l f o r v a r i a t i o n s i n i n d i v i d u a l vo lume o f d i s t r i b u t i o n by i n c l u d i n g body we igh t i n the c a l c u l a t i o n o f the p e r m e a b i l i t y i ndex ( a l t h o u g h i d e a l body we igh t may t h e o r e t i c a l l y be more p r o p o r t i o n a l t o body wa te r than i s a c t u a l body w e i g h t , no s i g n i f i c a n t d i f f e r e n c e was f ound when the p e r m e a b i l i t y i ndex was c a l c u l a t e d u s i n g i d e a l w e i g h t ) . However , t he c l e a r a n c e o f the t r a c e r f rom the b l o o d was no t c o n t r o l l e d . Tc-DTPA i s c l e a r e d f rom the b l o o d m a i n l y by the k i d n e y s ( 5 7 ) ; t h e r e f o r e , i t i s c o n c e i v a b l e t h a t i f r e n a l c l e a r a n c e were i m p a i r e d i n the smokers , e l e v a t e d b l o o d coun t s would be s e e n . The p o s i t i v e c o r r e l a t i o n f o u n d between the l u n g h a l f - l i f e and the b l o o d l e v e l s as measured by the p e r m e a b i l i t y i ndex s u g g e s t s , t h o u g h , t h a t t h i s i ndex i s a r e a s o n a b l e r e f l e c t i o n o f the t r a n s f e r o f the t r a c e r i n t o the b l o o d , a l t h o u g h c l e a r l y o t h e r f a c t o r s must be i n v o l v e d o r the c o r r e l a t i o n wou ld be s t r o n g e r . These f a c t o r s may w e l l be r e l a t e d t o the b e h a v i o u r o f the t r a c e r i n - 136 -e q u i l i b r a t i o n w i t h body wa te r and i t s e l i m i n a t i o n f rom the b l o o d . The e v i d e n c e s u p p o r t s the c o n c e p t o f a d e c r e a s e i n the e f f e c t i v e n e s s o f the d i f f u s i o n b a r r i e r p r e s e n t e d by the e p i t h e l i u m , as a r e s u l t o f c i g a r e t t e smoke e x p o s u r e . T h i s c o u l d r e s u l t f rom a reas o f denuded e p i t h e l i u m , an i n c r e a s e i n the e f f e c t i v e pore s i z e between c e l l s , o r m e t a b o l i c damage to the e p i t h e l i u m c e l l membranes such t h a t they a re no l o n g e r a b a r r i e r t o d i f f u s i o n o f the t r a c e r . S e v e r a l i n v e s t i g a t o r s u s i n g a n i m a l models have s u g g e s t e d t h a t changes i n the i n t e r e p i t h e l i a l j u n c t i o n s a re a l i k e l y cause o f i n c r e a s e d e f f e c t i v e po re s i z e . Damage t o j u n c t i o n a l complexes was s u g g e s t e d by S iman i and h i s a s s o c i a t e s (38) and Boucher and co-workers (39) were a b l e t o show q u a l i t a t i v e changes i n the j u n c t i o n a l s t r a n d s u s i n g f r e e z e f r a c t u r e t e c h n i q u e s . S i m i l a r l y , D a v i s and c o l l e a g u e s (34) showed j u n c t i o n a l complex d i s c o n t i n u i t i e s a f t e r ozone exposu re u s i n g f r e e z e f r a c t u r e . However , Wa lke r and h i s a s s o c i a t e s ( 7 8 ) , u s i n g q u a n t i t a t i v e t e c h n i q u e s , c o u l d f i n d no changes i n j u n c t i o n a l complexes a l o n g l a t e r a l c e l l s u r f a c e s i n g u i n e a p i g s exposed t o c i g a r e t t e smoke. E v i d e n c e f r om t h e i r s t udy s u g g e s t e d t h a t changes i n the t r i c e l l u l a r j u n c t i o n s a t the c o r n e r s o f the e p i t h e l i a l c e l l s may be the s i t e o f the i n c r e a s e d p e r m e a b i l i t y . Boucher (14) has p r o p o s e d t h r e e p o t e n t i a l mechanisms whereby j u n c t i o n a l damage may o c c u r . These i n c l u d e damage by r e a c t i v e o x i d a n t s p e c i e s e i t h e r d i r e c t ( e g : f rom c i g a r e t t e smoke) o r f rom PMN's r e c r u i t e d t o the a r e a , e n z y m a t i c c l e a v a g e o f the j u n c t i o n s as a r e s u l t o f the i n c r e a s e d e f f e c t i v e p r o t e o l y t i c a c t i v i t y , and m e t a b o l i c changes to the c e l l s t h e m s e l v e s . I t i s p o s s i b l e t h a t t h e s e mechanisms o r o t h e r s c o u l d r e s u l t i n damage no t o n l y t o the j u n c t i o n a l complexes but a l s o t o the c e l l membranes. - 137 -I t i s o f i n t e r e s t t h a t i n b o t h a n i m a l and human s t u d i e s , the e p i t h e l i a l p e r m e a b i l i t y r e t u r n s t o norma l d u r i n g the r e p a i r phase o f the i n j u r y ( 4 0 , 4 4 , 4 5 ) . The an ima l d a t a show t h a t the norma l e p i t h e l i u m i s p a r t i a l l y r e p l a c e d by a r e p a r a t i v e b a s a l c e l l l a y e r d u r i n g the r e p a i r p h a s e . T h i s s u g g e s t s t h a t the r e t u r n t o norma l may be based on t h e s e p r o l i f e r a t i n g b a s a l c e l l s wh i ch a re l a r g e and f l a t w i t h fewer c o r n e r s p e r u n i t o f s u r f a c e a r e a t han no rma l e p i t h e l i u m . In a s t u d y o f r a t t r a c h e a l e p i t h e l i a l r e g e n e r a t i o n , Gordon and co-workers (79) f ound t h a t i n t e r c e l l u l a r j u n c t i o n s were p r e s e n t between t h e s e b a s a l c e l l s s i x hours a f t e r i n j u r y . T h i s c o u l d be an i m p o r t a n t method o f r e s t o r i n g the b a r r i e r . Whether the a p p a r e n t l y norma l p e r m e a b i l i t y seen i n the p a t i e n t s i n the second s t udy as w e l l as i n p a t i e n t s w i t h s t a b l e asthma (42) i s ba sed on a r e p a i r i n g e p i t h e l i u m i s an i n t e r e s t i n g p o s s i b i l i t y . Such a mechanism might a l s o e x p l a i n the d a t a o f R i n d e r k n e c h t and a s s o c i a t e s (54) who a c c o u n t e d f o r the o b s e r v e d i n c r e a s e i n a l v e o l a r p e r m e a b i l i t y seen i n p a t i e n t s w i t h i n t e r s t i t i a l l u n g d i s e a s e by the i n c r e a s e d numbers o f Type I I a l v e o l a r e p i t h e l i a l c e l l s . These s m a l l c u b o i d a l c e l l s wou ld a l s o have i n c r e a s e d numbers o f po res pe r u n i t s u r f a c e a r e a when compared t o the no rma l Type I c e l l . Smokers , however , a re s u b j e c t t o r e p e a t e d a cu te i n j u r y w i t h c o n t i n u a l e p i t h e l i a l damage and i n c r e a s e d p e r m e a b i l i t y . Mason and h i s c o l l e a g u e s (56) have p r o v i d e d e v i d e n c e t h a t the i n c r e a s e i n e f f e c t i v e pore s i z e i n smokers i s r e l a t e d t o an i n c r e a s e i n \" p o r e d i m e n s i o n s \" r a t h e r than r i s e i n the number o f a c c e s s i b l e pa thways . He s t u d i e d the p r o p o r t i o n a t e c l e a r a n c e o f two i n d i c a t o r s o f d i f f e r e n t m o l e c u l a r s i z e and f o u n d t h a t c l e a r a n c e o f the l a r g e r i n d i c a t o r , -DTPA, i n c r e a s e d s i g n i f i c a n t l y more i n smokers than t h a t o f the s m a l l e r i n d i c a t o r , - 138 -TcO^,, s u g g e s t i n g a w i d e n i n g o f the pathway f o r d i f f u s i o n . I t was h y p o t h e s i z e d t h a t such an i n c r e a s e i n the p e r m e a b i l i t y o f the pu lmonary e p i t h e l i u m may l e a v e the u n d e r l y i n g s t r u c t u r e s more a c c e s s i b l e t o a g o n i s t s and thus r e s u l t i n h y p e r r e a c t i v i t y o f the a i rways ( 2 , 8 0 ) . However, a l t h o u g h t h i s d a t a and o t h e r s (43 ,45 ) show a c l e a r d i f f e r e n c e between smokers and non-smokers w i t h r e s p e c t to p e r m e a b i l i t y , no p a r a l l e l r e a c t i v i t y d i f f e r e n c e s between t h e s e g roups were seen i n t h i s s t u d y . T h i s i s c o n s i s t e n t w i t h the r e s u l t s o f Brown and a s s o c i a t e s (48) who s t u d i e d y o u n g , l i g h t smokers and f o u n d no r e a c t i v i t y d i f f e r e n c e between t h e s e s u b j e c t s and non-smokers . O t h e r s have f o u n d smokers t o be l e s s r e a c t i v e (46) o r more r e a c t i v e (10 ,47 ) t han c o n t r o l s w i t h no s i g n i f i c a n t change i n r e a c t i v i t y on c e s s a t o n o f smoking ( 4 9 ) . Baboons t a u g h t t o smoke (and i n whom s e l f - s e l e c t i o n can have no r o l e ) , were l e s s r e a c t i v e than baboons no t exposed t o c i g a r e t t e smoke ( 8 1 ) . I t has been s u g g e s t e d (46 ,81 ) t h a t one r e a s o n f o r the d e c r e a s e d r e a c t i v i t y i n smokers i n some s t u d i e s may be an a t t e n u a t i o n o f the a i rway r e s p o n s e t o h i s t a m i n e by b e t a - a d r e n e r g i c r e l a x a t i o n o f a i rway smooth musc l e as a r e s u l t o f n i c o t i n e - i n d u c e d e l e v a t i o n i n c i r c u l a t i n g c a t e c h o l a m i n e s ( 8 2 ) . B e t a - b l o c k a d e has been used by s e v e r a l worke rs p r i o r t o s t u d y i n g r e a c t i v i t y , a g a i n w i t h v a r i e d r e s u l t s . Hab ib and c o l l e a g u e s (19) f o u n d t h a t i n j e c t e d p r o p r a n a l o l had no e f f e c t on r e a c t i v i t y i n norma l s u b j e c t s . On the o t h e r h a n d , b e t a - b l o c k a d e does r e s u l t i n i n c r e a s e d r e a c t i v i t y i n a s t h m a t i c s (16) and i n n o n - a s t h m a t i c s s u f f e r i n g f rom hay f e v e r ( 1 8 ) . S i m i l a r i n c r e a s e d r e a c t i v i t y has a l s o been shown i n modera te t o heavy smokers by Z u s k i n and c o l l e a g u e s (20) who f o u n d no d e c r e a s e i n f l o w r a t e s i m m e d i a t e l y a f t e r smoking two c i g a r e t t e s - 139 -but s i g n i f i c a n t r e d u c t i o n i n f l o w r a t e s when the c i g a r e t t e s were p r e c e d e d by b e t a - b l o c k a d e . P loy-Song-Sang and co-workers (17) f ound t h a t norma l s u b j e c t s g i v e n IV h i s t a m i n e a l o n e o r IV p r o p r a n a l o l a l o n e showed no change i n pu lmonary f u n c t i o n but when the two agents were g i v e n t o g e t h e r an i n c r e a s e i n r e s i s t a n c e , a d e c r e a s e i n maximum f l o w r a t e s a t 50% l u n g c a p a c i t y and a d e c r e a s e i n d e n s i t y dependence d u r i n g p a r t i a l f l o w volume t e s t s o c c u r r e d . S t u d i e s o f norma l s u b j e c t s and o f worke rs exposed t o hemp, by Bouhuys e t a l ( 2 1 , 8 3 ) , a l s o showed i n c r e a s e d r e s p o n s i v e n e s s t o h i s t a m i n e and t o hemp f i b r e w i t h p r o p r a n a l o l p r e - t r e a t m e n t . In t h i s s t u d y b o t h smokers and non-smokers showed i n c r e a s e d r e a c t i v i t y t o h i s t a m i n e f o l l o w i n g b e t a - b l o c k a d e v i a p r o p r a n o l o l a e r o s o l . T h i s s u g g e s t s t h a t b e t a - a d r e n e r g i c mechanisms do p l a y a r o l e i n r e a c t i v i t y t o h i s t a m i n e bu t t h a t t h i s r o l e i s s i m i l a r i n b o t h g roups and no t s p e c i f i c t o a p o s s i b l e n i c o t i n e - i n d u c e d e f f e c t i n smokers o n l y . An a l t e r n a t e h y p o t h e s i s i s t h a t the h i s t a m i n e exposu re o f the t e s t i t s e l f r e s u l t s i n an i n c r e a s e i n c i r c u l a t i n g c a t e c h o l a m i n e s (84) wh i ch t e n d t o c o u n t e r a c t the e f f e c t o f h i s t a m i n e on a i rway c a l i b r e . W i th b e t a - b l o c k a d e , t h i s c o u n t e r b a l a n c i n g e f f e c t may be r e d u c e d thus r e s u l t i n g i n an appa ren t i n c r e a s e i n r e a c t i v i t y . The l a c k o f c o r r e l a t i o n between p e r m e a b i l i t y and r e a c t i v i t y i n t h i s s t udy may r e l a t e t o a d i f f e r i n g p h y s i c a l l o c u s f o r t h e s e r e s p o n s e s . The smokers i n t h i s s t u d y have p h y s i o l o g i c a l e v i d e n c e o f a b n o r m a l i t i e s i n the p e r i p h e r a l a i rways ( T a b l e I I I ) and t h i s has been shown by o t h e r s (85 ,86 ) t o be a s s o c i a t e d w i t h i n f l a m m a t o r y c h a n g e s . Thus the s i t e o f a l t e r e d p e r m e a b i l i t y , i f i t i s a s s o c i a t e d w i t h i n f l a m m a t i o n , may be i n the p e r i p h e r a l a i r w a y s , whereas a l t e r e d r e a c t i v i t y i s most l i k e l y a c e n t r a l a i rways phenomenon, g i v e n - 140 -the p r e d o m i n a n t l y c e n t r a l d i s t r i b u t i o n o f the i r r i t a n t r e c e p t o r s ( 8 7 ) . P re-and p o s t - a n t i g e n c h a l l e n g e The r e s u l t s o f the second p a r t o f t h i s s t udy p r o v i d e f u r t h e r e v i d e n c e t h a t i n c r e a s e d r e a c t i v i t y i s not the d i r e c t r e s u l t o f i n c r e a s e d e p i t h e l i a l p e r m e a b i l i t y . A l t h o u g h o n l y f o u r o f the s u b j e c t s s t u d i e d r e s p o n d e d t o the a n t i g e n c h a l l e n g e , t h e r e was an i n c r e a s e i n n o n - s p e c i f i c r e a c t i v i t y f o l l o w i n g the c h a l l e n g e i n t h r e e o f t h e s e f o u r s u b j e c t s . However , t h e r e was no concommitant r i s e i n p e r m e a b i l i t y a f t e r the p l i c a t i c a c i d c h a l l e n g e by wh i ch t o e x p l a i n t h i s i n c r e a s e d r e a c t i v i t y . The low PC^Q'S t o m e t h a c h o l i n e b e f o r e c h a l l e n g e and the low b a s e l i n e F EV^ ' s i n a l l bu t one s u b j e c t ( the same s u b j e c t who showed a d e p o s i t i o n p a t t e r n o f the t r a c e r i d e n t i c a l t o t hose i n S tudy 1) s ugges t t h a t even the n o n - r e s p o n d e r s i n t h i s s t udy cannot be c o n s i d e r e d \" n o r m a l \" s u b j e c t s and t h a t d i f f e r e n c e s seen i n the g roup as a whole compared t o the s u b j e c t s i n S tudy 1 may be i n d i c a t i v e o f changes due t o an a s t h m a - l i k e c o n d i t i o n . As i n the f i r s t p a r t o f the s t u d y , f a c t o r s r e l a t i n g t o d e p o s i t i o n o f the a e r o s o l , i f d i f f e r e n t f rom one assessment o f p e r m e a b i l i t y t o a n o t h e r , c o u l d c o n f o u n d the r e s u l t s . In t h e s e n i n e s u b j e c t s , t h e r e was, on the a v e r a g e , g r e a t e r c e n t r a l d e p o s i t i o n than i n the f i r s t s t u d y . T h i s p r o b a b l y r e f l e c t s the f a c t t h a t t h e r e was g r e a t e r b a s e l i n e a i rway o b s t r u c t i o n i n t h e s e p a t i e n t s , as e v i d e n c e d by the l ower mean FEV^, wh ich i s not s u r p r i s i n g g i v e n t h e i r r e f e r r a l t o t he c l i n i c f o r o c c u p a t i o n a l asthma i n v e s t i g a t i o n . The d i s a p p e a r a n c e h a l f - l i f e o f the t r a c e r i n a l l t h e s e p a t i e n t s was s h o r t e r t han t h a t o f the non-smokers i n the f i r s t s t u d y , s u g g e s t i n g an i n c r e a s e i n p e r m e a b i l i t y . The b l o o d l e v e l s o f the t r a c e r , however , were no t e l e v a t e d . - 141 -T h i s s u g g e s t s t h a t c l e a r a n c e f rom the l u n g s i s enhanced due t o i n c r e a s e d m u c o - c i l i a r y a c t i v i t y r a t h e r than i n c r e a s e d t r a n s f e r d i r e c t l y i n t o the b l o o d a c r o s s the l u n g mucosa l e p i t h e l i u m . T h i s i s c o n s i s t e n t w i t h the more c e n t r a l d e p o s i t i o n p a t t e r n and may a l s o r e f l e c t an i n c r e a s e i n mucous p r o d u c t i o n i n t h e s e s u b j e c t s . However , as d i s c u s s e d above , d i s a p p e a r a n c e o f the t r a c e r i n o t h e r s t u d i e s i s enhanced by more p e r i p h e r a l , a l v e o l a r d e p o s i t i o n r a t h e r than v i c e v e r s a . I t may be t h a t a peak i n l u n g r e t e n t i o n t ime i s r e a c h e d when d e p o s i t i o n i s p r i m a r i l y i n s m a l l a i rways where m u c o c i l i a r y and a l v e o l a r c l e a r a n c e s a re l i m i t e d and r e t e n t i o n t ime d e c r e a s e s when d e p o s i t i o n becomes p r e d o m i n a n t l y a l v e o l a r o r p r e d o m i n a n t l y i n l a r g e a i rways o r i f mucous p r o d u c t i o n i s i n c r e a s e d . The p r i m a r y q u e s t i o n b e i n g i n v e s t i g a t e d i n t h e s e p a t i e n t s was the d i f f e r e n c e i n p e r m e a b i l i t y b e f o r e and a f t e r c h a l l e n g e ; thus a change i n the p a t t e r n o f d e p o s i t i o n a f t e r a n t i g e n exposu re c o u l d a l t e r the a p p a r e n t p e r m e a b i l i t y and mask an i n c r e a s e i n a c t u a l p e r m e a b i l i t y o f the e p i t h e l i u m . A l t h o u g h no measurements were made o f the d i s t r i b u t i o n o f v e n t i l a t i o n b e f o r e and a f t e r c h a l l e n g e , the s u b j e c t i v e assessment o f the gamma camera images i n d i c a t e d no o b v i o u s changes i n the a e r o s o l d e p o s i t i o n p a t t e r n a f t e r the p l i c a t i c a c i d exposu re i n the non- re sponde r s and o n l y s l i g h t and i n c o n s i s t e n t changes i n the r e s p o n d e r s . I t i s no t p o s s i b l e t o a s s e s s the a f f e c t o f a l t e r e d d i s t r i b u t i o n i n t h e s e s u b j e c t s as i t i s no t appa ren t whether the changes seen wou ld l e a d t o enhanced c l e a r a n c e due t o more a l v e o l a r d e p o s i t i o n o r r e t a r d e d c l e a r a n c e due t o d e p o s i t i o n i n p e r i p h e r a l a i rways w i t h s l owe r m u c o - c i l i a r y c l e a r a n c e . The t l / 2 r e s u l t s i n d i c a t e t h a t c l e a r a n c e o f - 142 -the t r a c e r was p r o l o n g e d i n a l l s u b j e c t s ( r e s p o n d e r s and n o n - r e s p o n d e r s ) a f t e r a n t i g e n c h a l l e n g e , bu t the l a c k o f p a r a l l e l change i n the b l o o d appearance l e v e l s s u g g e s t s t h a t t h i s may a l s o be r e l a t e d t o m u c o - c i l i a r y a c t i v i t y . I t can be s p e c u l a t e d t h a t t h e r e i s a n o n - s p e c i f i c a l t e r a t i o n i n mucous p r o d u c t i o n o r c l e a r a n c e dynamics i n a l l t h e s e s u b j e c t s r e l a t i n g t o exposu re t o p l i c a t i c a c i d as an i r r i t a n t , w i t h b r o n c h o c o n s t r i c t i o n o c c u r r i n g o n l y i n the f o u r \" r e s p o n d e r s \" . The i n c r e a s e i n r e a c t i v i t y t h a t o c c u r r e d i n f o u r s u b j e c t s (3 r e s p o n d e r s and one non- responde r ) was no t r e f l e c t e d by any c o n s i s t e n t change i n p e r m e a b i l i t y , a g a i n s u g g e s t i n g , as i n the f i r s t s t u d y , no cause and e f f e c t r e l a t i o n s h i p between t h e s e two p a r a m e t e r s . These r e s u l t s c o r r e s p o n d w i t h those o f E lwood and c o l l e a g u e s (42) who f o u n d no d i f f e r e n c e i n mucosa l p e r m e a b i l i t y between s t a b l e a s t h m a t i c s and n o n - a s t h m a t i c s when p e r m e a b i l i t y was a s s e s s e d w i t h the Tc-DTPA t r a c e r d e p o s i t e d more c e n t r a l l y . In f a c t the t l / 2 f o r the norma l s u b j e c t s i n t h a t s t udy was 66 + 19 m i n . , v e r y s i m i l a r t o t h a t seen i n t h i s s t u d y . However , Boucher and h i s a s s o c i a t e s (35) d i d f i n d i n c r e a s e d p e r m e a b i l i t y i n a l l e r g i c 99m_ monkeys a f t e r a n t i g e n c h a l l e n g e t o x c - a l b u m i n and enhanced r e a c t i v i t y t o h i s t a m i n e and i n c r e a s e d p e r m e a b i l i t y t o t r i t i u m - l a b e l l e d h i s t a m i n e (36) a f t e r a n t i g e n c h a l l e n g e . S i m i l a r l y , E lwood and h i s c o l l e a g u e s (42) showed enhanced p e r m e a b i l i t y i n norma l human s u b j e c t s i m m e d i a t e l y f o l l o w i n g i n h a l a t i o n o f h i s t a m i n e . They p r o p o s e d t h a t h i s t a m i n e r e l e a s e by mast c e l l s as a r e s u l t o f a n t i g e n - a n t i b o d y i n t e r a c t i o n may a l t e r b r o n c h i a l - m u c o s a l p e r m e a b i l i t y thus a m p l i f y i n g the a l l e r g i c r e s p o n s e . T h i s s t u d y d i f f e r s f r om t h e s e p r e v i o u s i n v e s t i g a t i o n s i n t h a t the second - 143 -measurement o f p e r m e a b i l i t y was p e r f o r m e d s e v e r a l hours a f t e r a n t i g e n c h a l l e n g e . I t i s p o s s i b l e t h a t a t r a n s i e n t i n c r e a s e i n p e r m e a b i l i t y may have o c c u r r e d i m m e d i a t e l y a f t e r the c h a l l e n g e , pe rhaps r e l a t e d t o h i s t a m i n e r e l e a s e f rom mast c e l l s , bu t no p r o l o n g e d a l t e r a t i o n i n p e r m e a b i l i t y was s e e n , d e s p i t e the c o n t i n u e d i n c r e a s e i n n o n - s p e c i f i c r e a c t i v i t y f o l l o w i n g the a n t i g e n c h a l l e n g e . In summary, t h e s e s t u d i e s show t h a t a l t h o u g h b r o n c h i a l e p i t h e l i a l p e r m e a b i l i t y i s e l e v a t e d by c i g a r e t t e smoke, t h i s i s not f o l l o w e d by an i n c r e a s e i n a i rway r e a c t i v i t y r e g a r d l e s s o f the p r e s e n c e o r absence o f b e t a - b l o c k a d e ; and t h a t a l t h o u g h a n t i g e n c h a l l e n g e can r e s u l t i n an enhancement o f n o n - a l l e r g e n i c r e a c t i v i t y , no p a r a l l e l i n c r e a s e i n mucosa l p e r m e a b i l i t y o c c u r s . C l e a r l y , t h e r e i s no s p e c i f i c cause and e f f e c t r e l a t i o n s h i p between p e r m e a b i l i t y and r e a c t i v i t y . More l i k e l y t h e s e a re b o t h a s s o c i a t e d w i t h the i n f l a m m a t o r y r e a c t i o n but r e s u l t f rom the a c t i v a t i o n o f d i f f e r e n t p h y s i o l o g i c a l pa thways . Recent i n v e s t i g a t i o n by Ho l tzman and h i s c o l l e a g u e s (88) has p r o v i d e d a d d i t i o n a l e v i d e n c e f o r the a s s o c i a t i o n between i n f l a m m a t i o n and h y p e r - r e a c t i v i t y . They showed t h a t enhanced r e a c t i v i t y t o a c e t y l c h o l i n e i n dogs f o l l o w i n g ozone exposu re c o r r e l a t e s p o s i t i v e l y w i t h the number o f e p i t h e l i a l and s u b e p i t h e l i a l n e u t r o p h i l s i n the t r a c h e a . P a r t i c u l a r l y i n t e r e s t i n g i n t h e i r s t udy i s the f a c t t h a t f o u r o f the t e n dogs d i d no t show enhanced r e a c t i v i t y and t h e r e was no i n c r e a s e i n n e u t r o p h i l number i n t h e s e a n i m a l s . They a l s o f ound a p o s i t i v e c o r r e l a t i o n between the l e v e l o f r e a c t i v i t y and the i n c r e a s e i n n e u t r o p h i l number. These a u t h o r s - 144 -sugges t t h a t t h i s r e l a t i o n s h i p may be due t o the r e l e a s e of: i n f l a m m a t o r y m e d i a t o r s f rom the PMN's wh i ch a l t e r the b r o n c h i a l smooth musc l e d i r e c t l y o r a f f e c t i t s i n n e r v a t i o n such t h a t the musc l e i s more r e s p o n s i v e . They a l s o sugges t t h a t s u b t l e changes i n e p i t h e l i a l c e l l s d u r i n g the i n f l a m m a t i o n , wh i ch i n c r e a s e p e r m e a b i l i t y , may p l a y a r o l e i n enhanced r e a c t i v i t y by a l l o w i n g more e f f e c t i v e chemotax i s o f n e u t r o p h i l s . 0 ' B y r n e and h i s a s s o c i a t e s (89) have a l s o r e p o r t e d r e c e n t l y t h a t ozone i n d u c e d h y p e r - r e s p o n s i v e n e s s i n dogs i s e l i m i n a t e d by n e u t r o p h i l d e p l e t i o n . The s t u d i e s i n g u i n e a p i g s by H u l b e r t and co-workers ( 4 1 ) , however , i n d i c a t e t h a t r e a c t i v i t y i s i n c r e a s e d i m m e d i a t e l y f o l l o w i n g smoke-exposure and r e t u r n s toward norma l by the t ime the PMN numbers peak . C l e a r l y , t h i s q u e s t i o n rema ins u n r e s o l v e d a t t h i s t i m e . - 145 -REFERENCES - CHAPTER V I 1. Empey DW, L a i t i n e r L A , J a cobs L, G o l d WM, Nade l JA : Mechanisms o f b r o n c h i a l h y p e r r e a c t i v i t y i n norma l s u b j e c t s a f t e r upper r e s p i r a t o r y t r a c t i n f e c t i o n . Am Rev R e s p i r D i s 1976 ; 113 :131-139 2. Dimeo MJ , G l e n n MG, Ho l tzman MJ , S h e l l e r JR, N a d e l JA , Boushey HA: T h r e s h o l d c o n c e n t r a t i o n o f ozone c a u s i n g an i n c r e a s e i n b r o n c h i a l r e a c t i v i t y i n humans and a d a p t a t i o n w i t h r e p e a t e d e x p o s u r e s . Am Rev R e s p i r D i s 1981 ; 124:245-248 3. Go lden JA , N a d e l JA , Bouchey HA: B r o n c h i a l h y p e r i r r i t a b i l i t y i n h e a l t h s u b j e c t s a f t e r exposu re t o o z o n e . Am Rev R e s p i r D i s 1978 ; 118:287-294 4. Hotzman MJ , Cunningham JH , S h e l l e r JH , I r s i g l e r GB, Nade l JA , Boushey HA: E f f e c t o f ozone on b r o n c h i a l r e a c t i v i t y i n a t o p i c and n o n - a t o p i c s u b j e c t s . Am Rev R e s p i r D i s 1979 ; 120:1059-1067 5. C o c k c r o f t DW, R u f f i n RE , D o l o v i c h J , Ha rg reave F E : A l l e r g e n - i n d u c e d i n c r e a s e i n n o n - a l l e r g i c b r o n c h i a l r e a c t i v i t y . C l i n A l l e r g y 1977 ; 7:503-513 6. 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The impor t ance o f s t a r t i n g a i rway c a l i b e r . Am Rev R e s p i r D i s 1982 ; 126:849-854 14 . Boucher RC: Mechanisms o f p o l l u t a n t - i n d u c e d a i rways t o x i c i t y . C l i n C h e s t Med 1981 ; 2 :377-392 1 5 . S z e n t i v a n y i A : The b e t a - a d r e n e r g i c t h e o r y o f the a t o p i c a b n o r m a l i t y i n b r o n c h i a l as thma. J A l l e r g y 1968 ; 42 :202-232 16 . G r i e c o MH, P i e r s o n RN: Mechanism o f b r o n c h o c o n s t r i c t i o n due t o B e t a a d r e n e r g i c b l o c k a d e . J A l l e r g y C l i n Immunol 1971 ; 48 :143-152 1 7 . P loy-Song-Sang Y , C o r b i n RP, E n g e l L A : E f f e c t s o f i n t r a v e n o u s h i s t a m i n e on l u n g mechan i c s i n man a f t e r B e t a - b l o c k a d e . J A p p l P h y s i o l 1978 ; 44 :690-695 - 147 -18 . Townley RG, McGready S, Bewtra A : The e f f e c t o f b e t a a d r e n e r g i c b l o c k a d e on b r o n c h i a l s e n s i t i v i t y t o a c e t y l - b e t a - m e t h a c h o l i n e i n no rma l and a l l e r g i c r h i n i t i s s u b j e c t s . J A l l e r g y C l i n Immunol 1976 ; 57 :358-366 19 . Hab ib MP, Pare PD, E n g e l LA : V a r i a b i l i t y o f a i rway r e s p o n s e s t o i n h a l e d h i s t a m i n e i n norma l s u b j e c t s . J A p p l P h y s i o l 1979 ; 47 :51-58 2 0 . Z u s k i n E, M i t c h e l l CA , Bouhuys A : I n t e r a c t i o n between e f f e c t s o f B e t a b l o c k a d e and c i g a r e t t e smoke on a i r w a y s . J A p p l P h y s i o l 1974 ; 36 :449-452 21 . Bouhuys A : B y o s i n o s i s . A r c h E n v i r o n H e a l t h 1971 ; 23 :405-407 22 . R i c h a r d s o n J , B e l a n d J : N o n a d r e n e r g i c i n h i b i t o r y ne rvous s y s t em i n human a i r w a y s . 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S chneebe rge r E E , Ka rnovsky MJ: The i n f l u e n c e o f i n t r a v a s c u l a r f l u i d volume on the p e r m e a b i l i t y o f newborn and a d u l t mouse l u n g s t o u l t a s t r u c t u r a l p r o t e i n t r a c e r s . J C e l l B i o l 1971 ; 49 :319-334 62 . S chneebe rge r E E : The p e r m e a b i l i t y o f the a l v e o l a r c a p i l l a r y membrane t o u l t r a s t r u c t u r a l p r o t e i n t r a c e r s . Ann NY Acad S c i 1974 ; 221 :238-243 6 3 . Egan EA, N e l s o n RM, O l v e r RE: Lung i n f l a t i o n and a l v e o l a r p e r m e a b i l i t y t o n o n - e l e c t r o l y t e s i n the a d u l t sheep i n v i v o . J P h y s i o l 1976 ; 260:409-424 64 . Egan EA: Lung i n f l a t i o n , l u n g s o l u t e p e r m e a b i l i t y , and a l v e o l a r edema. J A p p l P h y s i o l 1982 ; 53:121-125 6 5 . Mead J : Volume d i s p l a c e m e n t body p l e t h y smograph f o r r e s p i r a t o r y measurements i n human s u b j e c t s . J A p p l P h y s i o l 1960 ; 15 :736-740 66 . M o r r i s J F , K o s k i A , Johnson L C : S p i r o m e t r i c s t a n d a r d s f o r h e a l t h y non-smoking a d u l t s . Am Rev R e s p i r D i s 1971 ; 103 :57-67 - 153 -6 7 . B u i s t AS , Ross BB: P r e d i c t e d v a l u e s f o r c l o s i n g volume u s i n g a m o d i f i e d s i n g l e b r e a t h n i t r o g e n t e s t . Am Rev R e p i r D i s 1973 ; 107:744-752 68 . B u i s t AS , Ross BB: Q u a n t i t a t i v e a n a l y s i s o f the a l v e o l a r p l a t e a u i n the d i a g n o s i s o f e a r l y a i rway o b s t r u c t i o n . Am Rev R e s p i r D i s 1973 ; 108:1078-1087 6 9 . C h r i s t o f o r i d i s A J , T o m a s h e f s k i J F , M i t c h e l l R I : Use o f an u l t r a s o n i c n e b u l i z e r f o r the a p p l i c a t i o n o f o r o p h a r y n g e a l , l a r y n g e a l and t r a c h e o b r o n c h i a l a n e s t h e s i a . C h e s t 1971 ; 59 :629-633 70. C o c k c r o f t DW, K i l l i a n DN, M e l l o n JA , Ha rg reaves F E : B r o n c h i a l r e a c t i v i t y t o i n h a l e d h i s t a m i n e : Method and c l i n i c a l s u r v e y . C l i n A l l e r g y 1977 ; 7:235-243 71 . S a n c h i s J , D o l o v i c h M, Cha lmers R, Newhouse M: Q u a n t i t a t i o n o f r e g i o n a l a e r o s o l c l e a r a n c e i n the norma l human l u n g . J A p p l P h y s i o l 1972 ; 33 :757-762 72 . T a s k Group on Lung Dynamics : D e p o s i t i o n and r e t e n t i o n models f o r i n t e r n a l d o s i m e t r y o f the human r e s p i r a t o r y t r a c t . H e a l t h P h y s i c s 1966 ; 12 :173-207 73 . Y e a t e s DB, A s p i n N, L e v i s o n H, Jones MT, B ryan A C : M u c o c i l i a r y t r a n s p o r t r a t e s i n man. J A p p l P h y s i o l 1975 ; 39 :487-495 74. L o u r e n c o RV, K l imek MF, Borowsk i C J : D e p o s i t i o n and c l e a r a n c e o f 2u p a r t i c l e s i n the t r a c h e o - b r o n c h i a l t r e e o f norma l s u b j e c t s -smokers and non-smokers . J C l i n I n v e s t 1971 ; 50:1411-1420 75 . D o l o v i c h MB, S a n c h i s J , Rossman C , Newhouse MT: A e r o s o l p e n e t r a n c e : a s e n s i t i v e i ndex o f p e r i p h e r a l a i rways o b s t r u c t i o n . J A p p l P h y s i o l 1976 ; 40 :468-471 - 154 -76 . Comroe JH , F o r s t e r RE , Dubo i s AB , B r i c o e WA, C a r l s e n E: The Lung C l i n i c a l P h y s i o l o g y and Pu lmonary F u n c t i o n T e s t s . C h i c a g o : Y e a r Book M e d i c a l P u b l i s h e r s , 1962 77 . R i z k NW, Luce JM, P r i c e DC, H o e f f e l J , Mur ray J F : F a c t o r s 99 i n f l u e n c i n g c l e a r a n c e o f a e r o s o l i z e d T c - d i e t h y l e n e - t r i a m i n e 99 p e n t a a c e t a t e ( Tc-DTPA) f rom c a n i n e l u n g s . P h y s i o l o g i s t 1982 ; 2 5 : 3 1 3 a 78 . Wa lke r DC, MacKenz ie A , H u l b e r t WC, Hogg J C : C i g a r e t t e smoke exposu re and t i g h t j u n c t i o n s o f the e p i t h e l i a l c e l l s o f g u i n e a p i g t r a c h e a . Am Rev R e s p i r D i s 1982 ; 125:264 79 . Gordon RE , Lane BP: R e g e n e r a t i o n o f r a t t r a c h e a l e p i t h e l i u m a f t e r m e c h a n i c a l i n j u r y . Am Rev R e s p i r D i s 1976 ; 113:799-807 80 . Hogg JC : B r o n c h i a l mucosa l p e r m e a b i l i t y and i t s r e l a t i o n s h i p t o a i rways h y p e r r e a c t i v i t y . J A l l e r g y C l i n Immunol 1981 ; 67 :421-425 8 1 . Roehrs JD , Rogers WR, Johanson WG: B r o n c h i a l r e a c t i v i t y t o i n h a l e d m e t h a c h o l i n e i n c i g a r e t t e smoking baboons . J A p p l P h y s i o l 1981 ; 50 :754-760 82 . C r y e r PE , Haymond MW, S a n t i a g o JV , Shah SD: Smok ing , c a t e c h o l a m i n e s and c o r o n a r y h e a r t d i s e a s e . C a r d i o v a s c Med 1977 ; 2 :471-476 8 3 . Bouhuys A , Doug las J S , Guya t t AR: P h a r m a c o l o g i c a l m o d i f i c a t i o n o f h i s t a m i n e - m e d i a t e d a i rway r e s p o n s e s . J C l i n I n v e s t 1971 ; 50 :9 ( a b s t r a c t ) 84 . S t a s z e w s k a - B a r c z a k J , Vane JR: The r e l e a s e o f c a t e c h o l a m i n e s f r o m the a d r e n a l m e d u l l a by h i s t a m i n e . B r i t J Pha rmaco l 1965 ; 25 :728-742 - 155 -8 5 . C o s i o M, Ghezzo H, Hogg J C , C o r b i n R, L o v e l a n d M, Dosman J , Macklem PT: The r e l a t i o n s h i p between s t r u c t u r a l changes i n s m a l l a i rways and pu lmonary f u n c t i o n t e s t s . New E n g l J Med 1978 ; 298:1277-1281 86 . Be rend N, T h u r l b e c k WM: C o r r e l a t i o n s o f maximum e x p i r a t o r y f l o w w i t h s m a l l a i rway d i m e n s i o n s and p a t h o l o g y . J A p p l P h y s i o l 1982 ; 52 :346-351 8 7 . Widdicombe JG : R e f l e x c o n t r o l o f t r a c h e o b r o n c h i a l smooth musc l e i n e x p e r i m e n t a l and human as thma. I n : A u s t e n KF , L i c h e n s t e i n EM, e d s , As thma : P h y s i o l o g y , Immunopharmacology and T r e a t m e n t . Second I n t e r n a t i o n a l Symposium. New Y o r k : Academic P r e s s , 1977 88 . Ho l tzman MJ , F a b b r i LM, O ' B y rne PM, G o l d BD, A i zawa H, W a l t e r s EH , A l p e r t SE , Nade l JA : Impor tance o f a i rway i n f l a m m a t i o n f o r h y p e r r e s p o n s i v e n e s s i n d u c e d by o z o n e . Am Rev R e s p i r D i s 1 9 8 3 ; 127 :686-690 8 9 . O ' B y rne P, W a l t e r s E, G o l d B, A i zawa H, F a b b r i L, A l p e r t S, N a d e l J , Ho l tzman M: N e u t r o p h i l d e p l e t i o n i n h i b i t s a i rway h y p e r r e s p o n s i v e n e s s i n d u c e d by o z o n e . P h y s i o l o g i s t 1983 ; 26 :35 - 156 -F i g u r e 8 D e p o s i t i o n p a t t e r n o f a e r o s o l i z e d Tc-DTPA i n l u n g s -gamma camera image o f two t y p i c a l s u b j e c t s , 1 non-smoker and 1 smoker showing d i f f u s e d e p o s i t i o n o f the t r a c e r i n bo th c a s e s . - 157 -c o 0 fX 100 • 87 74 S, 61 48 35 •smokers Inon-smokers 14 23 Time (min.) 32 F i g u r e 9 / / D i s a p p e a r a n c e o f Tc-DTPA f r om l u n g s - gamma camera coun t s pe r m inu te (CPM) r e m a i n i n g i n l u n g s as % o f CPM a t t ime z e r o (7 m inu tes a f t e r b e g i n n i n g o f a e r o s l i z a t i o n o f t r a c e r ) v s . t i m e ; mean + S.D - 158 -50-40 ^ 1 1 i i i i 12 24 36 48 Time (min.) F i g u r e 10 Appearance o f Tc-DTPA i n b l o o d - p e r m e a b i l i t y index v s . t i m e ; mean + S .D . ( see t e x t f o r d e f i n i t i o n o f p e r m e a b i l i t y i n d e x ) . - 159 -! [HISTAMINE] mg/ml | •—. histamine only j .—* histamine + propranolol i . i F i g u r e 11 I n d i v i d u a l h i s t a m i n e d o s e - r e s p o n s e c u r v e s - % d e c r e a s e i n FEV^ f r om p r e - h i s t a m i n e l e v e l s f o l l o w i n g h i s t a m i n e dose g i v e n ; m . r e sponse f o l l o w i n g a e r o s o l i z e d h i s t a m i n e a l o n e , r e sponse f o l l o w i n g a e r o s o l i z e d p r o p r a n o l o l p l u s h i s t a m i n e ; s u b j e c t number i n d i c a t e d i n upper l e f t o f each g r a p h . - 160 -DAY 1 DAY 3 NON RESPONDER • • 1 RESPONDER Figure 12 Deposition pattern of aerosolized Tc-DTPA in patients before (Day 1) and a f t e r (Day 3) antigen challenge -gamma camera image of two t y p i c a l subjects, 1 responder and 1 non-responder to p l i c a t i c acid, showing more cent r a l deposition in both cases, compared to Study 1 subjects (see Figure 8). Deposition i s not changed a f t e r antigen challenge i n the non-responder but i s s l i g h t l y more peripheral a f t e r challenge in the responder. - 161 -TABLE I I I S u b j e c t C h a r a c e t e r i s t i . e s and Pu lmonary F u n c t i o n - S tudy 1 <- % P r e d i c t e d -f S u b j e c t Age Sex Pack Y r s . F E V l A N 2 / 1 C C _ V 5 0 Smoked FVC TLC Non-Smokers 1 30 F 0 80 119 99 87 97 2 28 M 0 76 102 70 98 102 3 23 F 0 85 106 61 60 74 4 28 M 0 77 114 130 105 98 5 35 M 0 84 131 64 75 141 6 25 M 0 84 121 82 97 123 7 46 M 0 83 108 82 127 114 8 34 M 0 83 124 79 95 106 X 31 82 116 83 93 107 SD 7 3 10 22 20 20 Smokers 9 25 M 10 86 105 63 162 106 10 33 M 20 88 98 87 111 84 11 33 M 18 84 118 128 111 112 12 37 M 11 72 106 139 80 60 13 31 M 13 74 111 98 113 71 14 28 F 9 86 111 104 62 106 15 41 F 24 77 103 160 145 83 16 22 F 16 83 91 124 141 74 17 32 M 17 78 103 91 114 82 18 42 M 34 77 103 183 124 87 x\" 32 17 80 105 118 116 86 SD 6 8 6 7 36 30 17 p v a l u e N.S N.S . N.S . <.05 <.05 <.05 - 162 -TABLE IV 3 Permeability and R e a c t i v i t y Data - Study 1 Subj, Tl/2 U/min. P I 1 0 PI 25 PI60 p c 2 0 R I p c 2 0 R I A RI (min) (mg/ml) (mg/ml) (no B-block) (with B-block) Non-Smokers 1 52.7 1.50 10.4 18.7 29.4 64 7.8 47.9 15.0 7.2 2 157.0 0.45 5.9 8.0 25.9 25.1 15.3 18.8 17.3 2.0 3 53.0 1.56 5.1 11.1 18.4 64 6.1 20.0 17.3 11.2 4 217.6 0.15 3.0 5.4 13.9 11.6 21.7 4.0 33.3 11.6 5 166.0 0.42 21.2 30.6 39.2 26.9 14.7 16.0 18.3 3.6 6 57.0 1.38 12.5 21.0 23.8 53.7 12.2 41.7 16.1 3.9 7 75.6 1.00 9.2 15.2 22.0 64 9.4 26.9 14.7 7.3 8 101.0 0.72 7.4 10.2 11.4 64 7.2 64 8.9 1.7 x 110.0 0.90 9.3 15.0 23-0 11.8 17.6 6.1 SD 62.7 0.54 5.7 8.2 8.9 5.3 7.0 3.9 Smokers 9 42.9 1.79 16.5 ,23.7 27.0 64 7.8 47.8 . 12.8 5.0 10 29.6 2.45 58.0 48.2 34.7 - - - - -11 34.4 2.47 25.0 30.0 32.4 64 2.8 64 5.0 2.2 12 48.3 1.59 18.6 21.4 19.9 14. 7 18.3 26.0 16.0 -2.3 13 77.4 0.90 20.7 24.9 26.9 25. 6 16.0 - - -14 28.7 3.01 27.1 37.0 39.3 56. 2 8.9 42.7 13.3 4.4 15 32.0 2.52 38.7 49.2 52.6 5. 4 27.8 2.4 38.3 10.5 16 61.0 1.24 20.3 30.0 44.0 21. 3 14.7 3.0 43.3 28.6 17 47.0 1.62 20.8 28.1 32.5 64 7.9 64 8.3 0.4 18 22.8 3.59 47.9 41.6 33.5 64 3.9 36.3 17.8 13.9 X 42.4 2.12 29.4 33-4 34.5 12.0* 19.4* 7.8 SD 16.8 0.84 14.1 10.1 9.3 8.0 13.9 . 9.9 p value 4.005 <..005 7 1 . 5 * 6 .0 1 0 . 3 1 3 . 6 12 .2 3.2 4.1 5.0 a f t e r c h a l l e n g e ^ b e f o r e c h a l l e n g e ( p < . 0 1 ) S tudy 1 non-smokers S tudy 1 smokers - 164 -V I I S m a l l A i rway S t r u c t u r e and F u n c t i o n i n Pe r sons Exposed t o M i n e r a l Dust and Fume - Compared t o C i g a r e t t e Smokers I n t r o d u c t i o n S t u d i e s c a r r i e d ou t by C o s i o and h i s c o l l e a g u e s (1) and o t h e r i n v e s t i g a t o r s ( 2 ,3 ) have i n d i c a t e d t h a t i n f l a m m a t i o n i n the p e r i p h e r a l a i rways i s an e a r l y e ven t i n the p a t h o g e n e s i s o f c h r o n i c o b s t r u c t i v e pu lmonary d i s e a s e i n c i g a r e t t e smokers . These i n v e s t i g a t i o n s have been d i s c u s s e d i n p r e c e d i n g c h a p t e r s . A i rway p a t h o l o g i c a l a b n o r m a l i t i e s have a l s o been r e p o r t e d i n pe r sons exposed t o i n d u s t r i a l d u s t s and fumes (4-7) a l t h o u g h i n most c a se s t h e s e p e o p l e a re a l s o c i g a r e t t e smokers and the p a r t i c u l a r e f f e c t s o f the e n v i r o n m e n t a l p o l l u t a n t s a re d i f f i c u l t t o s e p a r a t e f rom the e f f e c t s o f the c i g a r e t t e smoke. The r e s p o n s e o f the l u n g i n t e r s t i t i u m t o c e r t a i n o c c u p a t i o n a l p o l l u t a n t s such as c o a l , s i l i c a , a s b e s t o s , and o t h e r d u s t s wh ich cause pu lmonary f i b r o s i s have been w e l l d e s c r i b e d (8) a l t h o u g h the s p e c i f i c c e l l u l a r e v e n t s r e s p o n s i b l e f o r the f i b r o t i c r e s p o n s e t o t h e s e agen ts a re no t c o m p l e t e l y u n d e r s t o o d . Many e a r l i e r a c c o u n t s o f the p a t h o l o g y o f t hese pneumocon ioses d e s c r i b e d the i n t e r s t i t i a l f i b r o t i c r e s p o n s e wh ich r e s u l t s i n a r e s t r i c t i v e f u n c t i o n a l impa i rment bu t h e l d the a i rways t o be m a i n l y u n t o u c h e d . O t h e r s t u d i e s have d e m o n s t r a t e d a i rway o b s t r u c t i o n and p a t h o l o g i c a l changes i n the s m a l l a i rways w i t h exposu re t o v a r i o u s i n d u s t r i a l d u s t s wh i ch may o r may no t a l s o r e s u l t i n p n e u m o c o n i o s i s . - 165 -As e a r l y as 1935 S imson (4) d e s c r i b e d the p a t h o l o g y o f the e a r l y s i l i c o t i c l e s i o n u s i n g 3 - d i m e n s i o n a l r e c o n s t r u c t i o n t e c h n i q u e s . He showed t h a t the i n h a l a t i o n o f i n j u r i o u s d u s t f rom the Rand g o l d mines r e s u l t e d i n a c c u m u l a t i o n o f d u s t c e l l s and f r e e p igment i n the w a l l s o f r e s p i r a t o r y b r o n c h i o l e s and a l v e o l a r d u c t s b e f o r e any s i g n o f the w h o r l e d f i b r o s i s a p p e a r e d , and t h a t s i l i c o t i c n o d u l e s were u s u a l l y s i t u a t e d i n the ang l e fo rmed by two d i v i d i n g r e s p i r a t o r y b r o n c h i o l e s . E p i d e m i o l o g i c s t u d i e s o f s i l i c o s i s i n South A f r i c a n g o l d mines ( 9 ,10 ) have r e v e a l e d e v i d e n c e o f o b s t r u c t i v e a i rways a b n o r m a l i t i e s a l t h o u g h the r o l e p l a y e d by c i g a r e t t e smoking was f o u n d t o be g r e a t e r t han t h a t o f the mine d u s t i n the deve lopment o f t h e s e a b n o r m a l i t i e s ( 1 1 ) . C o a l d u s t exposu re a l s o r e s u l t s i n a b n o r m a l i t i e s i n t he v i c i n i t y o f p e r i p h e r a l a i r w a y s . The c o a t d u s t macu le wh i ch i s c h a r a c t e r i s t i c o f s i m p l e c o a l worke r s pneumocon io s i s c o n s i s t s m a i n l y o f c a rbonaceous d e p o s i t s a round r e s p i r a t o r y b r o n c h i o l e s wh ich may be d i l a t e d and show some c e n t r i l o b u l a r emphysema. A c l e a r r e l a t i o n s h i p has been shown between exposu re t o r e s p i r a b l e c o a l d u s t and d e c l i n e i n FEVX ( 1 2 ) . A i rway l e s i o n s i n a s b e s t o s exposu re have r e c e n t l y been s u f f i c i e n t l y w e l l c h a r a c t e r i z e d t o be i n c l u d e d i n the d e f i n i t i o n o f a s b e s t o s i s pu t f o r w a r d by the Pneumocon ios i s Committee o f the C o l l e g e o f A m e r i c a n P a t h o l o g i s t s ( 1 3 ) . T h i s commit tee s u g g e s t s t h a t f i b r o s i s o f r e s p i r a t o r y b r o n c h i o l e s a l o n g w i t h the p r e s e n c e o f a s b e s t o s b o d i e s i n d i c a t e s the e a r l y fo rm o f a s b e s t o s i s . P a t h o l o g i c e v i d e n c e o f t h i s - 166 -l e s i o n i n a s b e s t o s - e x p o s e d worke rs has been p r e s e n t e d by Wr igh t and Churg ( 5 ) . However , t h e s e i n v e s t i g a t o r s have a l s o n o t e d the same l e s i o n i n worke rs exposed t o non-asbes tos m i n e r a l d u s t and have s u g g e s t e d t h a t i t i s no t s p e c i f i c t o a s b e s t o s exposu re but r a t h e r a n o n - s p e c i f i c r e a c t i o n t o m i n e r a l d u s t ( 6 ) . S e v e r a l s t u d i e s o f f u n c t i o n a l a b n o r m a l i t i e s i n a s b e s t o s exposed i n d i v i d u a l s have i n d i c a t e d i n c r e a s i n g s m a l l a i rway a b n o r m a l i t i e s c o r r e l a t i n g w i t h i n c r e a s i n g d u s t exposu re ( 14-16 ) , a l t h o u g h t h e s e s t u d i e s a re a l s o c o m p l i c a t e d by c i g a r e t t e smoking among most o f the s u b j e c t s . E v i d e n c e o f a i rway o b s t r u c t i o n has a l s o been r e p o r t e d among worke r s exposed t o o c c u p a t i o n a l env i ronment p o l l u t a n t s wh i ch a re no t a s s o c i a t e d w i t h the deve lopment o f p n e u m o c o n i o s i s . A 12 y e a r f o l l o w u p s t u d y o f worke r s i n e l e v e n P a r i s f a c t o r i e s (17) demons t r a t ed t h a t the r a t e o f d e c l i n e i n FEV^ c o r r e l a t e d p o s i t i v e l y w i t h exposu re t o m i n e r a l d u s t (even e x c l u d i n g exposu re t o s i l i c a ) , g r a i n d u s t , gases and h e a t . However , P a rkes p o i n t s o u t , i n h i s book O c c u p a t i o n a l Lung D i s o r d e r s ( 8 ) , t h a t i t i s i m p o r t a n t t o d i s t i n g u i s h between the p r e s e n c e o f c h r o n i c cough and sputum wh ich i s c l e a r l y a s s o c i a t e d w i t h the i n h a l a t i o n o f d u s t s and fumes and a i r f l o w o b s t r u c t i o n w i t h r e s p i r a t o r y d i s a b i l i t y wh i ch he r e p o r t s as p r i n c i p a l l y a s s o c i a t e d w i t h c i g a r e t t e smoking and s o c i a l f a c t o r s , a l t h o u g h a s y n e r g i s t i c e f f e c t between d u s t and c i g a r e t t e smoke i s s u g g e s t e d . S i m i l a r l y , Morgan (18) has f ound t h a t non-smoking m ine r s have f u n c t i o n a l i n d i c a t i o n s o f l a r g e a i rway n a r r o w i n g w h i l e smoking m ine r s have s m a l l a i rway o b s t r u c t i o n as w e l l . - 167 -Sea ton (19) s u g g e s t s t h a t the m a t t e r i s no t q u i t e so c l e a r - c u t and d i s c u s s e s s e v e r a l s t u d i e s among c o a l m ine r s wh ich i n d i c a t e an a d d i t i o n a l e f f e c t o f d u s t exposu re on p e r i p h e r a l a i r w a y s . A p o s s i b l e s y n e r g i s t i c e f f e c t between smoke and i n d u s t r i a l d u s t exposu re c o u l d be r e l a t e d t o the i n c r e a s e i n e p i t h e l i a l p e r m e a b i l i t y i n c i g a r e t t e smokers wh i ch was demons t r a t ed i n the p r e c e d i n g c h a p t e r . T h i s change c o u l d r e s u l t i n enhanced a b s o r p t i o n o f d u s t p a r t i c l e s . C o n v e r s e l y , d u s t p a r t i c l e s i n i n s p i r e d a i r may a c t as c a r r i e r s f o r a d s o r b e d t o x i c gases f rom the c i g a r e t t e smoke o r o t h e r s o u r c e s . A l t h o u g h s t u d i e s such as t h o s e d e s c r i b e d above s u g g e s t t h a t i n d u s t r i a l d u s t exposu re may a f f e c t the a i r w a y s , the n a t u r e o f t h i s e f f e c t i s no t known. I t i s u n c l e a r whether the a i rway r e s p o n s e i s s i m i l a r t o t h a t p r o d u c e d by smoke o r whether the p a t h o l o g y can be d i s t i n g u i s h e d . I t i s p o s s i b l e t h a t the s m a l l a i rway i n f l a m m a t o r y r e s p o n s e d e m o n s t r a t e d i n c i g a r e t t e smokers may be a l t e r e d o r enhanced as a r e s u l t o f i n c r e a s e d e p i t h e l i a l p e r m e a b i l i t y wh i ch may r educe the e f f e c t i v e n e s s o f the e p i t h e l i a l b a r r i e r t o d u s t s o r o t h e r i r r i t a n t s . The s t udy d e s c r i b e d be low was d e s i g n e d t o t e s t t h i s h y p o t h e s i s , t o d e t e r m i n e i f the s m a l l a i rway p a t h o l o g i c a l changes seen i n c i g a r e t t e smokers were m o d i f i e d o r i n c r e a s e d by a d d i t i o n a l exposu re t o m i n e r a l d u s t o r fume. T h i s i n v o l v e d a compa r i son o f pu lmonary f u n c t i o n , s m a l l a i rway p a t h o l o g y , and c h e s t r a d i o g r a p h s i n s u b j e c t s w i t h m i n e r a l d u s t o r fume exposu re and t h o s e w i t h o u t d u s t e x p o s u r e , i n d i v i d u a l l y matched f o r age and smoking h i s t o r y . - 168 -M e t h o d s : 1. S u b j e c t s : S u b j e c t s were s e l e c t e d f rom a l l p a t i e n t s a d m i t t e d t o S t . P a u l ' s H o s p i t a l f r om O c t o b e r 1978 t o December , 1982 f o r s u r g i c a l r e s e c t i o n o f a l o b e o r l u n g due t o , i n most c a s e s , l u n g c a n c e r . Any p a t i e n t w i t h e v i d e n c e o f o b s t r u c t i v e p n e u m o n i t i s o r whose l e s i o n was f o u n d t o o b s t r u c t a segmenta l o r l a r g e r a i rway was e x c l u d e d . O c c u p a t i o n a l h i s t o r i e s were o b t a i n e d f rom a l l p a t i e n t s b e f o r e s u r g e r y . E v e r y p a t i e n t who r e p o r t e d t en o r more y e a r s as a m ine r o r w i t h exposu re t o m i n e r a l d u s t o r fume i n a non-min ing o c c u p a t i o n was s e l e c t e d f o r the s t u d y . A l t o g e t h e r t h e r e were 19 such p a t i e n t s . C o n t r o l s u b j e c t s were chosen f rom among t h o s e p a t i e n t s who r e p o r t e d no o c c u p a t i o n a l exposu re t o d u s t o r fume o f any k i n d . One c o n t r o l s u b j e c t was chosen f o r each exposed s u b j e c t , matched f o r age + 1 y e a r and smoking h i s t o r y . The smoking h i s t o r y match t o o k i n t o a c c o u n t b o t h c u r r e n t smoking s t a t u s and l i f e t i m e exposu re (based on c i g a r e t t e s p e r day x y e a r s = c i g a r e t t e y e a r s ) . 2. Pu lmonary F u n c t i o n : Pu lmonary f u n c t i o n t e s t s were p e r f o r m e d w i t h i n one week b e f o r e s u r g e r y u s i n g a volume d i s p l a c e m e n t body p l e t h y smograph as d e s c r i b e d i n - 169 -the p r e c e d i n g c h a p t e r . In a d d i t i o n t o d e t e r m i n a t i o n o f the s u b d i v i s i o n s o f l u n g vo lume , maximum e x p i r a t o r y f l o w volume c u r v e s and washout c u r v e s as d e s c r i b e d above , s t e a d y - s t a t e CO d i f f u s i n g c a p a c i t y and f r a c t i o n a l up take o f CO was c a l c u l a t e d u s i n g the p r e d i c t i o n f o r m u l a e o f Ba tes and c o l l e a g u e s ( 2 0 ) . 3. S m a l l A i rway P a t h o l o g y : S u r g i c a l l y r e s e c t e d spec imens were f i x e d by i n f l a t i o n t h r o u g h the b ronchus u s i n g 10% f o r m a l i n o r 3% g l u t a r a l d e h y d e a t 25 cmH^O p r e s s u r e and subsequen t immers ion i n f i x a t i v e f o r 24 h o u r s . H i s t o l o g i c a l spec imens were p r e p a r e d f rom 3-6 s t r a t i f i e d random b l o c k s f rom the m e d i a l and l a t e r a l s l i c e s t aken f rom a r eas away f rom any o b s t r u c t i o n . P a r a f f i n s e c t i o n s (5 u t h i c k ) were s t a i n e d w i t h h e m a t o x y l i n and e o s i n , M a s s o n ' s t r i c h o m e , and p e r i o d i c a c i d - S c h i f f s t a i n s . E v e r y n o n - c a r t i l a g e n o u s a i rway l e s s than 2mm i n t e r n a l d i a m e t e r was g r a d e d i n a s i n g l e b l i n d f a s h i o n u s i n g the p i c t o r i a l g r a d i n g s y s t em d e s c r i b e d by C o s i o and h i s c o l l e a g u e s (1) f o r membranous b r o n c h i o l e s and W r i g h t and a s s o c i a t e s (3) f o r r e s p i r a t o r y b r o n c h i o l e s . A s e p a r a t e g rade was d e t e r m i n e d f r om 0-3 f o r each a i rway d e p e n d i n g on the p r e s e n c e and s e v e r i t y o f each o f the f o l l o w i n g p a t h o l o g i c a l v a r i a b l e s : m u r a l i n f l a m m a t i o n , f i b r o s i s , smooth musc l e h y p e r t r o p h y , and p i g m e n t , and squamous and g o b l e t c e l l m e t a p l a s i a i n membranous b r o n c h i o l e s ; and m u r a l i n f l a m m a t i o n , f i b r o s i s , smooth musc l e h y p e r t r o p h y , and p igment - 170 -and i n t r a l u m e n a l macrophages i n r e s p i r a t o r y b r o n c h i o l e s . A s i n g l e s c o r e was then d e t e r m i n e d f o r each v a r i a b l e f o r each s u b j e c t by summing the i n d i v i d u a l a i rway s c o r e and e x p r e s s i n g t h i s t o t a l as a p e r c e n t a g e o f the maximum p o s s i b l e s c o r e . R e s p i r a t o r y and membranous b r o n c h i o l e s were a s s e s s e d on s e p a r a t e o c c a s i o n s so t h a t the s c o r e s f o r one were no t i n f l u e n c e d by the s c o r e s f o r the o t h e r . 4. R a d i o l o g y and p a t h o l o g i c / r a d i o R r a p h i c c o r r e l a t i o n : P r e - o p e r a t i v e c h e s t r a d i o g r a p h s were r e a d i n a s i n g l e - b l i n d f a s h i o n by a s e p a r a t e i n v e s t i g a t o r , e x p e r i e n c e d i n the assessment o f r a d i o g r a p h i c p n e u m o c o n i o s i s , and a s s i g n e d a pneumocon io s i s g rade a c c o r d i n g t o the 1971 ILO-U/C c l a s s i f i c a t i o n ( 2 1 ) . In o r d e r t o d e t e r m i n e the h i s t o l o g i c c o r r e l a t e o f the r a d i o g r a p h i c d e n s i t i e s s e e n , s l i c e s were t aken f rom the whole l u n g o r l o b e spec imen (1/4 i n c h t h i c k ) and d r i e d i n a microwave oven a t the l o w e s t v o l t a g e s e t t i n g f o r s e v e r a l d a y s . These d r i e d s l i c e s were then r a d i o g r a p h e d and the p r e c i s e l o c a t i o n o f any d e n s i t i e s seen on the f i l m were l o c a t e d on the s l i c e . T h i s a r e a o f t i s s u e was then removed f r o m the l u n g s l i c e , r e immersed i n f o r m a l i n f o r 24 h o u r s , and p r o c e s s e d f o r the p r e p a r a t i o n o f p a r a f f i n s e c t i o n s . T h i s was done because the randomly s e l e c t e d t i s s u e spec imens d i d not r e v e a l any o b v i o u s s i l i c o t i c l e s i o n s no r o t h e r e v i d e n c e o f p n e u m o c o n i o s i s . - 171 -5. Da ta a n a l y s i s : Pu lmonary f u n c t i o n t e s t v a l u e s and p a t h o l o g y v a r i a b l e s c o r e s were compared f o r exposed and non-exposed s u b j e c t s u s i n g s t u d e n t ' s p a i r e d t - t e s t . When f u n c t i o n d a t a was m i s s i n g f o r any s u b j e c t , b o t h t h a t s u b j e c t and i t s c o r r e s p o n d i n g match were e l i m i n a t e d f rom the a n a l y s i s f o r t h a t t e s t . M i n e r s exposed t o d u s t were compared to non-miners exposed t o d u s t o r fume by comput ing the d i f f e r e n c e between exposed and matched c o n t r o l s i n each g r o u p , t hen a p p l y i n g s t u d e n t ' s u n p a i r e d t - t e s t t o compare t h e s e d i f f e r e n c e s . - 172 -R e s u l t s : Exposu re h i s t o r i e s o f the 19 m i n e r a l d u s t o r fume exposed s u b j e c t s a r e shown i n T a b l e V I I (p 1 8 7 ) . Ten were m i n e r s , w i t h a l l b u t one o f t h e s e b e i n g h a r d r o c k m i n e r s . Of the n i n e n o n - m i n e r s , a m a j o r i t y were exposed m a i n l y t o fume r a t h e r than d u s t a l o n e , b e i n g w e l d e r s and s m e l t e r w o r k e r s . As i n d i c a t e d i n T a b l e V I I I (p 188) the n i n e t e e n exposed worke rs had a mean age o f 6 2 . 3 + 10 .3 y e a r s and c i g a r e t t e exposu re o f 981 .3 + 520.7 c i g a r e t t e y e a r s . Of t h e s e , f i v e were ex-smokers and the rema inde r c u r r e n t smokers o r had o n l y s t o p p e d smoking w i t h i n 6 months . The c o n t r o l s were 62 .4 + 10 .6 y e a r s o l d and had a smoke exposu re o f 1020.2 + 488 .2 c i g a r e t t e y e a r s w i t h the same p r o p o r t i o n o f ex- and c u r r e n t smoke r s . Pu lmonary F u n c t i o n : F u n c t i o n a l d i f f e r e n c e s between the d u s t and fume exposed worke r s and matched c o n t r o l s a re shown i n T a b l e V I I I (p 1 8 8 ) . These i n c l u d e s i g n i f i c a n t l y l ower f l o w r a t e s (FEV^, V 5 Q and V ^ ) and i n c r e a s e d A N ^ / I i n d i c a t i n g more a i rway o b s t r u c t i o n and p e r i p h e r a l a i rways a b n o r m a l i t i e s i n the exposed s u b j e c t s . When the exposed g roup was d i v i d e d a c c o r d i n g t o o c c u p a t i o n i n t o a m i n i n g g roup and a n o n - m i n i n g , d u s t o r fume exposed g roup and each g roup compared to t h e i r c o r r e s p o n d i n g c o n t r o l s , the r e s u l t s i n d i c a t e d f u n c t i o n a l d i f f e r e n c e s f rom c o n t r o l s i n b o t h o c c u p a t i o n a l g roups t o a p p r o x i m a t e l y the same e x t e n t ( T a b l e s IX p 189 and X p 1 9 0 ) . A l t h o u g h i n these s u b g r o u p s , - 173 -o n l y the f l o w r a t e s a t low l u n g vo lumes a re s i g n i f i c a n t l y d i f f e r e n t f rom c o n t r o l s t h e r e i s a t r e n d t o more a i rway o b s t r u c t i o n i n b o t h g r o u p s . When the h e a v i e s t smokers among the m i n e r s a re s i n g l e d ou t ( T a b l e IX p 189) t h e s e f u n c t i o n a l d i f f e r e n c e s become more p r o n o u n c e d , s u g g e s t i n g a s y n e r g i s t i c e f f e c t between smoke and d u s t . D i r e c t compa r i son o f m ine r s and non-miners exposed t o d u s t and fume c o u l d no t be c a r r i e d ou t as the m i n e r s a re s i g n i f i c a n t l y o l d e r (66 .4 y e a r s compared t o 57 .8 y e a r s ) and have smoked more (1154 vs 889 c i g a r e t t e y e a r s ) t han the n o n - m i n e r s . Compar i son o f the d i f f e r e n c e s between each s u b j e c t and the matched c o n t r o l however r e v e a l e d no s i g n i f i c a n t d i f f e r e n c e s between t h e s e two groups f o r any o f t he pu lmonary f u n c t i o n v a r i a b l e s . S m a l l A i rway P a t h o l o g y : T a b l e XI (p 191) shows the s m a l l a i rway p a t h o l o g y v a r i a b l e s f o r the exposed and c o n t r o l s u b j e c t s . The re was s i g n i f i c a n t l y more m u r a l f i b r o s i s i n b o t h membranous and r e s p i r a t o r y b r o n c h i o l e s and more g o b l e t c e l l m e t a p l a s i a o f membranous b r o n c h i o l e s i n the l u n g s o f the exposed w o r k e r s . Examples o f t h e s e l e s i o n s a re shown i n F i g u r e 13 (p 195) . T a b l e X I I (p 192) shows t h e s e v a r i a b l e s b roken down by o c c u p a t i o n a l g r o u p . The r e s u l t s i n t h i s t a b l e i n d i c a t e t h a t most o f the i n c r e a s e d s m a l l a i rway p a t h o l o g y p r e v i o u s l y n o t e d i n the exposed g roup was a t t r i b u t a b l e t o changes i n the s m a l l a i rways o f the non-miners exposed t o d u s t o r fume, and t h e r e were no d i f f e r e n c e s o b s e r v e d i n s m a l l a i rway p a t h o l o g y between m i n e r s and t h e i r matched - 174 -c o n t r o l s . A g a i n , compa r i son o f m ine r s and non-miners by i n v e s t i g a t i o n o f the d i f f e r e n c e s between the s u b j e c t s and c o n t r o l s , c o n f i r m e d t h a t the non-miners had s i g n i f i c a n t l y more f i b r o s i s i n b o t h r e s p i r a t o r y and membranous b r o n c h i o l e s (p < .05) and t h e r e were no d i f f e r e n c e s between the two exposed groups f o r any o t h e r p a t h o l o g y v a r i a b l e s . R a d i o g r a p h s : The r a d i o g r a p h i c assessments a re shown i n T a b l e X I I I (p 1 9 3 ) . Seven o f the 9 m i n e r s f o r whom r a d i o g r a p h s were a v a i l a b l e were g r a d e d as p o s i t i v e f o r p n e u m o c o n i o s i s . Th ree o f the o t h e r dus t/ fume exposed g roup had changes s u g g e s t i n g p o s s i b l e d u s t exposu re and one c o n t r o l s u b j e c t had s i m i l a r c h a n g e s . R a d i o g r a p h i c / p a t h o l o g i c c o r r e l a t i o n : D r i e d l u n g s l i c e s were o b t a i n e d f rom a l l o f the exposed s u b j e c t s and f r om t h r e e o f the c o n t r o l s , chosen r andomly . D e n s i t i e s s i m i l a r t o t hose seen on the p r e - o p e r a t i v e c h e s t r a d i o g r a p h (and c l a s s i f i e d as p n e u m o c o n i o t i c l e s i o n s ) were i d e n t i f i e d i n o n l y t h r e e c a s e s , each b e i n g one o f the m ine r s p r e v i o u s l y g r a d e d f o r p o s i t i v e p n e u m o c o n i o s i s . H i s t o l o g i c e x a m i n a t i o n o f the t i s s u e r e s p o n s i b l e f o r the d e n s i t i e s r e v e a l e d the c l a s s i c w h o r l e d f i b r o t i c n o d u l e s c h a r a c t e r i s t i c o f s i l i c o s i s (see F i g u r e 14 p 1 9 7 ) . In a d d i t i o n , s u b p l e u r a l c a l c i f i c a t i o n was i d e n t i f i e d b o t h r a d i o l o g i c a l l y and h i s t o l o g i c a l l y i n a f o u r t h c a s e . - 175 -D i s c u s s i o n : The r e s u l t s o f t h i s s t udy sugges t t h a t b o t h f u n c t i o n a l and s t r u c t u r a l changes o c c u r i n r e s p o n s e t o m i n e r a l d u s t o r fume i n e x c e s s o f t h o s e a t t r i b u t a b l e t o c i g a r e t t e smok ing . The re a re however , c e r t a i n f e a t u r e s o f t h i s s t u d y t h a t must be t aken i n t o c o n s i d e r a t i o n when e v a l u a t i n g the r e s u l t s . O c c u p a t i o n a l h i s t o r i e s o f a l l s u b j e c t s were o b t a i n e d p r e - o p e r a t i v e l y by q u e s t i o n a i r e w i t h o u t r e f e r e n c e t o any s t u d y wh i ch may make use o f t h i s i n f o r m a t i o n . T h i s has the d e s i r a b l e a s p e c t o f m i n i m i z i n g i n t e r v i e w e r b i a s but u n f o r t u n a t e l y no d e t a i l e d i n f o r m a t i o n was o b t a i n e d about a c t u a l exposu re c o n d i t i o n s f o r any o f the s u b j e c t s . C o n s e q u e n t l y , no s p e c i f i c c o n c l u s i o n s can be drawn r e l a t i n g the f i n d i n g s t o p a r t i c u l a r e x p o s u r e s . I t does seem r e a s o n a b l e , however , t o a s s e s s the worke rs exposed i n m i n i n g o c c u p a t i o n s s e p a r a t e l y f rom those exposed i n non-min ing j o b s . The d i f f e r e n c e s o b s e r v e d i n l u n g s t r u c t u r e (bo th i n h i s t o l o g y and r a d i o g r a p h y ) between t h e s e two groups s u p p o r t t h i s s e p a r a t i o n . A second i m p o r t a n t f e a t u r e o f t h i s s t udy i s the c o n c e n t r a t i o n on p a t h o l o g y i n the s m a l l a i r w a y s . No a t t empt was made t o a s s e s s a l l the h i s t o l o g i c a l changes wh i ch may have o c c u r r e d i n the l u n g t i s s u e . T h u s , f u n c t i o n a l o r r a d i o g r a p h i c changes may be f ound wh ich do no t c o r r e l a t e w i t h the p a t h o l o g y as a s s e s s e d i n t h i s s t u d y , bu t t h e r e may i n f a c t be c o r r e l a t i o n s w i t h l a r g e a i rway o r l u n g i n t e r s t i t i a l c h a n g e s . T h i r d l y , the p a t i e n t s s t u d i e d a l l had a l u n g o r l o b e removed because o f p o s s i b l e c a r c i n o m a . A l t h o u g h the s e c t i o n s s t u d i e d f o r - 176 -p a t h o l o g i c a l a n a l y s i s were t aken as f a r away as p o s s i b l e f r om the tumor o r o t h e r l e s i o n , an a s sumpt i on i s i m p l i e d t h a t the l e s i o n does no t a d v e r s e l y a f f e c t the r e s t o f the l u n g . A l s o , i t i s assumed t h a t t he l o b e o r l u n g removed i s r e p r e s e n t a t i v e o f the l u n g as a w h o l e . The f a c t t h a t b o t h the c o n t r o l g roup and the exposed g roup were drawn f r o m the same p o p u l a t i o n o f tumor p a t i e n t s u n d e r g o i n g r e s e c t i o n , m i n i m i z e s t h i s p r o b l e m as f a r as c o m p a r i s o n between t h e s e g roups i s c o n c e r n e d ; bu t the p r o b l e m rema ins i n d raw ing c o n c l u s i o n s r e l a t i n g s t r u c t u r e and f u n c t i o n i n any one g r o u p . T h i s i s p a r t i c u l a r l y e v i d e n t i n the r e s u l t s stemming f rom the a n a l y s i s o f r a d i o g r a p h s and the subsequent s e a r c h f o r the p a t h o l o g i c a l c o r r e l a t e o f the r a d i o g r a p h d e n s i t i e s i n the d r i e d l u n g s l i c e s . The d i f f e r e n c e s i n pu lmonary f u n c t i o n o b s e r v e d between the exposed and non-exposed groups i n d i c a t e s l i g h t l y more a i r f l o w o b s t r u c t i o n i n the exposed g roup r a t h e r than a r e s t r i c t i v e l u n g d i s e a s e as m igh t be e x p e c t e d i f the exposed g roup had e x t e n s i v e i n t e r s t i t i a l i n v o l v e m e n t w i t h f i b r o s i s o r f i b r o t i c n o d u l e s . T h i s absence o f r e s t r i c t i o n i s i n k e e p i n g w i t h the r a d i o g r a p h i c e v i d e n c e wh i ch i n d i c a t e d o n l y e a r l y pneumocon io s i s i n some c a s e s . The a d d i t i o n a l a i rway o b s t r u c t i o n i s c o n s i s t e n t w i t h many o t h e r r e p o r t s o f a i rway i n v o l v e m e n t i n m i n e r s and o t h e r i n d u s t r i a l worke rs exposed t o d u s t . The s i m i l a r f u n c t i o n a l dec rements i n b o t h m ine r s and dus t/ fume exposed non-miners s u g g e s t s t h a t t h e s e f u n c t i o n a l a b n o r m a l i t i e s a re no t s p e c i f i c t o any s i n g l e a g e n t . S i m i l a r r e s u l t s were r e p o r t e d r e c e n t l y by M a n f r e d a and h i s c o l l e a g u e s (22) who found the pu lmonary f u n c t i o n - 177 -pa ramete r s d e r i v e d f r om maximal e x p i r a t o r y maneuvers and the s i n g l e - b r e a t h t e s t t o be worse i n o v e r 1000 m ine r s and s m e l t e r worke rs than i n a g e n e r a l p o p u l a t i o n samp le . I n t e r e s t i n g l y , among the c u r r e n t smokers , the s m e l t e r worke rs had more f u n c t i o n a l a b n o r m a l i t i e s than d i d the unde rg round m i n e r s . The s t r i k i n g i n c r e a s e i n f u n c t i o n a l d i f f e r e n c e s between exposed and non-exposed among the h e a v i e s t smokers i n t h i s s t udy l e n d s s u p p o r t t o the c o n c e p t o f s y n e r g i s m between c i g a r e t t e smoke e x p o s u r e and m i n e r a l d u s t . U n f o r t u n a t e l y the s m a l l number o f heavy smokers among the non-min ing exposed g roup made i t i m p o s s i b l e t o d e t e r m i n e i f t h i s e f f e c t was s i m i l a r i n b o t h exposu re c a t e g o r i e s . R e l a t i n g the pu lmonary f u n c t i o n d i f f e r e n c e s seen between the exposed and non-exposed worke r s to the a i rway p a t h o l o g y i s d i f f i c u l t i n t h e s e s u b j e c t s , p a r t i c u l a r l y because the s i g n i f i c a n t changes seen i n the a i rway p a t h o l o g y were o b s e r v e d o n l y among the n o n - m i n e r s , whereas the f u n c t i o n a l d i f f e r e n c e s were f o u n d e q u a l l y i n b o t h exposed g r o u p s . The c o n s i d e r a b l e f i b r o s i s o b s e r v e d a round the p e r i p h e r a l a i rways i n the non-min ing d u s t o r fume exposed s u b j e c t s i s v e r y s i m i l a r t o t h a t r e p o r t e d r e c e n t l y by Churg and Wr i gh t (5 ,6 ) i n bo th a s b e s t o s and n o n - a s b e s t o s m i n e r a l d u s t e x p o s u r e s . The absence o f i n c r e a s e d a i rway f i b r o s i s (compared t o non-exposed smokers) i n the m ine r s ( T a b l e X I I ) , however , r ema ins t o be e x p l a i n e d . - 178 -Some f a c t o r s wh i ch may be i m p o r t a n t i n d e t e r m i n i n g the n a t u r e and p r o g r e s s i o n o f a i rway l e s i o n s i n t h e s e g roups i n c l u d e the l e n g t h o f t ime spen t unde rg round o r a t the o r e f a c e , and o t h e r exposu re c o n d i t i o n s such as the p r e s e n c e o f d i e s e l e x h a u s t , and wet o r d r y m i n i n g t e c h n i q u e s . I t i s p o s s i b l e t h a t the a i rway f i b r o s i s seen i n the non-miners and the r a d i o g r a p h i c pneumocon ios i s seen i n the m i n e r s r e f l e c t d i f f e r i n g d e p o s i t i o n p a t t e r n s o f the i n h a l e d d u s t s o r fumes i n t h e s e w o r k e r s . E v i d e n c e f o r the impor t ance o f d e p o s i t i o n i n d e t e r m i n i n g the n a t u r e o f the f i b r o t i c r e s p o n s e i s f o u n d i n the a n i m a l mode l o f b l e o m y c i n - i n d u c e d f i b r o s i s . P a r e n t e r a l a d m i n i s t r a t i o n o f b l e o m y c i n i n baboons p roduces i n t e r s t i t i a l f i b r o s i s w h i l e i n t r a t r a c h e a l i n s t i l l a t i o n p roduces a i rway f i b r o s i s p a r t i c u l a r l y i n the w a l l s o f r e s p i r a t o r y b r o n c h i o l e s ( 2 4 ) . PMN's o r macrophages may be p r e s e n t i n bo th the a i rways o r a l v e o l i and may be a c t i v a t e d by p a r t i c u l a t e p h a g o c y t o s i s o r by exposu re o r o x i d e n t s and r e l e a s e f a c t o r s wh i ch i n i t i a t e the f i b r o g e n e s i s . T h i s e x p l a n a t i o n may a l s o a c coun t i n p a r t f o r the e x c e s s g o b l e t c e l l m e t a p l a s i a seen i n the non-miners but no t i n the m i n e r s . An i n c r e a s e i n mucous p r o d u c t i o n i n r e l a t i o n t o d u s t exposu re has been o b s e r v e d i n s e v e r a l s t u d i e s ( 7 , 2 2 , 2 5 ) and Morgan (18) has s u g g e s t e d t h a t t h i s i s a l a r g e a i rway r e s p o n s e t o d u s t . Pe rhaps the m i n e r a l fume t o wh i ch the non-miners were exposed p e n e t r a t e s beyond the l a r g e a i rways by a d s o r p t i o n on smoke p a r t i c l e s and p rovokes a g r e a t e r p e r i p h e r a l mucous h y p e r s e c r e t i o n ( i n t h i s c a se e v i d e n c e d by an e x c e s s o f g o b l e t c e l l s ) t han t h a t i n d u c e d by the smoke a l o n e . E x a m i n a t i o n o f - 179 -the l a r g e r , c a r t i l a g e n o u s a i rways o f t hese worke r s may p r o v i d e a d d i t i o n a l i n f o r m a t i o n about mucous p r o d u c t i o n i n r e l a t i o n t o d u s t e x p o s u r e . I t i s i m p o r t a n t t o no te t h a t no o t h e r s i g n i f i c a n t d i f f e r e n c e s appea red i n the o t h e r s m a l l a i rway p a t h o l o g y v a r i a b l e s a s s e s s e d . In p a r t i c u l a r , t h e r e was no i n c r e a s e i n p igment d e p o s i t i o n i n the a i rway w a l l s as m igh t be e x p e c t e d i n the d u s t exposed w o r k e r s . T h i s c o r r e s p o n d s w i t h p r e v i o u s r e p o r t s i n wh i ch the amount o f d u s t seen i n h i s t o l o g i c a l spec imens bo re no r e l a t i o n t o the s e v e r i t y o f f i b r o s i s , the deg ree o f f u n c t i o n a l i m p a i r m e n t , o r the e x t e n t o f the r a d i o g r a p h i c changes ( 7 , 8 , 2 6 ) . C o s i o and h i s c o l l e a g u e s (1) s t u d i e d s m a l l a i rway p a t h o l o g y i n a s i m i l a r s e r i e s o f 36 r e s e c t e d s p e c i m e n s , d i v i d e d i n t o g roups a c c o r d i n g to s e v e r i t y o f the l e s i o n s f o u n d . They r e p o r t e d t h a t i n f l a m m a t i o n and f i b r o s i s o f a i rway w a l l s and squamous m e t a p l a s i a were the e a r l i e s t p a t h o l o g i c a l changes t o o c c u r i n the deve lopment o f d i s e a s e i n the s m a l l a i rways and t h a t the amount o f i n f l a m m a t o r y i n f i l t r a t e d i d no t change as the d i s e a s e p r o g r e s s e d . F i b r o s i s , musc l e h y p e r t r o p h y and p igment d e p o s i t i o n i n c r e a s e d p r o g r e s s i v e l y , w h i l e g o b l e t c e l l m e t a p l a s i a became s i g n i f i c a n t o n l y i n the most s e v e r e c a s e s . W r i g h t and co-workers ( 3 ) , s t u d y i n g the same l a r g e g roup o f p a t i e n t s f rom wh i ch t h e s e d u s t exposed s u b j e c t s were t a k e n , examined s m a l l a i rway p a t h o l o g y d i f f e r e n c e s i n smokers , ex-smoke r s , and non-smokers . T h e i r r e s u l t s i n d i c a t e d t h a t membranous b r o n c h i o l e s i n smokers and ex-smokers had i n c r e a s e d g o b l e t c e l l m e t a p l a s i a compared t o non-smokers and t h a t s i g n i f i c a n t i n c r e a s e s i n i n f l a m m a t i o n , f i b r o s i s , - 180 -p i g m e n t , and i n t r a l u m e n a l macrophages were f o u n d i n the r e s p i r a t o r y b r o n c h i o l e s o f smokers and ex-smoke r s . Compar i son o f the r e s u l t s o f t h i s s t udy w i t h those o f C o s i o (1) and Wr i gh t (3) and t h e i r c o l l e a g u e s sugges t t h a t the r e s p o n s e t o m i n e r a l d u s t and fume exposu re d i f f e r s f rom the r e s p o n s e t o c i g a r e t t e smoke a l o n e i n t h a t f i b r o s i s and g o b l e t c e l l m e t a p l a s i a p r edomina t e w h i l e the o t h e r v a r i a b l e s a re u n a l t e r e d f r om the l e v e l a t t r i b u t a b l e t o the smoke e x p o s u r e . T h i s p redominance o f f i b r o u s t i s s u e d e p o s i t i o n wh i ch i s i r r e v e r s i b l e , o v e r i n f l a m m a t i o n wh i ch may be r e v e r s i b l e , c o u l d a c c o u n t f o r the o b s e r v a t i o n r e p o r t e d by W i l e s and Fau re (27) t h a t c h r o n i c o b s t r u c t i v e b r o n c h i t i s i n e x - g o l d m ine r s i s i r r e v e r s i b l e w h i l e ex-smokers t end t o show improved f u n c t i o n , on the a v e r a g e , o v e r c u r r e n t smokers ( 3 ) . A l t h o u g h the o n l y o b j e c t i v e a n a l y s i s o f the h i s t o l o g i c a l spec imens f r om t h e s e p a t i e n t s was t h a t o f s m a l l a i rway p a t h o l o g y , a s u b j e c t i v e assessment was u n d e r t a k e n o f the l u n g i n t e r s t i t i u m and r e v e a l e d no o b v i o u s d i f f e r e n c e s i n exposed and non-exposed s u b j e c t s o r i n m ine r s and n o n - m i n e r s . S p e c i f i c a l l y no s i l i c o t i c nodu l e s were s e e n , nor was any e x c e s s i v e f i b r o t i c s c a r r i n g appa ren t i n t he exposed w o r k e r s , d e s p i t e the r a d i o g r a p h i c appearance o f s i m p l e p n e u m o c o n i o s i s i n many o f the m i n e r s . T h i s s u b j e c t i v e f i n d i n g l e d t o the subsequen t d r y i n g and r e - a n a l y s i s o f l u n g s l i c e s t o d e t e r m i n e the h i s t o l o g i c a l c o r r e l a t e o f the r a d i o g r a p h i c d e n s i t i e s . The sha rp r e d u c t i o n i n the number o f c a s e s i n wh i ch n o d u l e s o r o t h e r d e n s i t i e s were seen when s i n g l e d r i e d s l i c e s were examined ( a l t h o u g h i n t hese c a s e s , the nodu l e s - 181 -were i d e n t i f i e d as s i l i c o t i c - t y p e l e s i o n s ) , and the f a i l u r e t o l o c a t e any such l e s i o n s i n the s t r a t i f i e d random b l o c k s o r i g i n a l l y a n a l y s e d , i n d i c a t e the ext reme h e t e r o g e n e i t y o f the i n t e r s t i t i a l p r o c e s s i n pneumocon io s i s and sugges t t h a t e x t e n s i v e s a m p l i n g i s n e c e s s a r y i n o r d e r t o d i s c o v e r the t r u e e x t e n t o f t h e s e l e s i o n s i n s u s p e c t e d c a s e s . The s p e c i f i c s t r u c t u r a l a b n o r m a l i t i e s r e s p o n s i b l e f o r the a d d i t i o n a l pu lmonary f u n c t i o n decrements o b s e r v e d i n the exposed worke rs canno t be d e t e r m i n e d f rom t h i s s t u d y . The exces s s m a l l a i rway changes i n the non-miners may w e l l a c coun t f o r the i n c r e a s e i n a i r f l o w o b s t r u c t i o n i n t h i s g roup but the same cannot be s a i d f o r the m i n e r s . I t i s u n l i k e l y t h a t the pa renchyma l a b n o r m a l i t i e s i n d i c a t e d by r a d i o g r a p h y a re r e s p o n s i b l e f o r the f u n c t i o n a l changes i n t h i s g roup as t h e s e were m i n i m a l i n most c a se s and the c o r r e l a t i o n between r a d i o g r a p h i c pneumocon io s i s and pu lmonary f u n c t i o n i s g e n e r a l l y f o u n d t o be poo r ( 2 6 , 2 8 , 2 9 ) . A b n o r m a l i t i e s i n l a r g e a i rways o r changes i n the l u n g i n t e r s t i t i u m (whether emphysematous o r f i b r o t i c ) not d e t e c t e d i n t h i s i n v e s t i g a t i o n may a l s o c o n t r i b u t e t o the o b s e r v e d f u n c t i o n a l c h a n g e s . In t h e i r s e r i e s o f 52 c a se s o f a t y p i c a l p n e u m o c o n i o s i s , G a e n s l e r (26) and h i s c o l l e a g u e s f ound t h a t the most i m p o r t a n t h i s t o l o g i c a l d e t e r m i n a n t o f l u n g f u n c t i o n was the i n t e g r i t y o f the l u n g t i s s u e between the l a r g e , o b v i o u s f i b r o t i c f o c i , w i t h the s e v e r i t y o f i n t e r s t i t i a l pneumonia c o r r e l a t i n g c l o s e l y t o p h y s i o l o g i c a l impa i rmen t . However , i n t h e i r p a t i e n t s , pu lmonary f u n c t i o n was c h a r a c t e r i s t i c a l l y r e s t r i c t i v e r a t h e r than o b s t r u c t i v e . Exposu re t o i n h a l e d p o l l u t a n t s o t h e r than m i n e r a l d u s t o r fume - 182 -c o u l d a l s o p l a y a r o l e i n the deve lopment o f b o t h the f u n c t i o n a l and a i rway s t r u c t u r a l m a n i f e s t a t i o n s i n t h e s e w o r k e r s . These c o u l d i n c l u d e d i e s e l e m i s s i o n s , v a r i o u s gases such as ozone and n i t r o g e n o x i d e s , and o r g a n i c vapours wh i ch may be p r e s e n t i n the w o r k p l a c e and have been i m p l i c a t e d i n the p r o d u c t i o n o f r e s p i r a t o r y a b n o r m a l i t i e s ( 8 , 1 7 , 3 0 , 3 1 ) . I t i s c l e a r , however , t h a t o c c u p a t i o n a l exposu re t o a i r b o r n e p o l l u t a n t s p r e s e n t i n m i n i n g o r m e t a l p r o c e s s i n g s h o p s , i n c o m b i n a t i o n w i t h c i g a r e t t e smok ing , r e s u l t s i n a d d i t i o n a l a b n o r m a l i t i e s o f s m a l l a i rway s t r u c t u r e and f u n c t i o n and t h a t the p r e s e n c e o f e x c e s s i v e f i b r o s i s and g o b l e t c e l l m e t a p l a s i a i n h i s t o l o g i c a l spec imens may s i g n a l such exposu re i n c e r t a i n c a s e s , a l t h o u g h the absence o f t h e s e f e a t u r e s does no t r u l e ou t e x p o s u r e . F i n a l l y , t h i s s t u d y c o n f i r m s t h a t f u n c t i o n a l impa i rment g r e a t e r than t h a t a c c o u n t e d f o r by c i g a r e t t e smok ing , can o c c u r i n t h e s e worke rs i n the absence o f r a d i o l o g i c a l e v i d e n c e o f p n e u m o c o n i o s i s . - 183 -REFERENCES - CHAPTER V I I 1. C o s i o M, Ghezzo H, Hogg J C , C o r b i n F, L o v e l a n d M, Dosman J , Macklem PT: The r e l a t i o n s between s t r u c t u r a l changes i n s m a l l a i rways and p u l m o n a r y - f u n c t i o n t e s t s . New E n g l J Med 1978 ; 298:1277-1281 2. N iewoehner DE , K l e i n e r m a n J , R i c e DB: P a t h o l o g i c changes i n t he p e r i p h e r a l a i rways o f young smokers . New E n g l J Med 1974 ; 291 :755-758 3. W r i g h t J L , Lawson LM, Pa re PD, Wiggs B J , Kennedy S, Hogg J C : Morpho logy o f p e r i p h e r a l a i rways i n c u r r e n t smokers and ex-smoke r s . Am Rev R e s p i r D i s 1983 ; 127:474-477 4 . S imson FW: R e c o n s t r u c t i o n mode ls showing the m o d e r a t e l y e a r l y s i m p l e s i l i c o t i c p r o c e s s and how i t a f f e c t s d e f i n i t e p a r t s o f the p r i m a r y u n i t o f the l u n g . J Pa th Bac t 1935 ; 40 :37-44 5. W r i gh t J , Churg A : M o r p h o l o g i c f e a t u r e s o f s m a l l a i rway l e s i o n s i n p a t i e n t s w i t h a s b e s t o s e x p o s u r e . Human P a t h o l 1983 , i n p r e s s 6 . Churg A , W r i gh t J L : S m a l l a i rway l e s i o n s i n p a t i e n t s exposed t o non a s b e s t o s m i n e r a l d u s t s . Human P a t h o l 1983 ; 14 :688-693 7. Doug las AN , Lamb D, R u c k l e y VA : B r o n c h i a l g l a n d d i m e n s i o n s i n c o a l m i n e r s : i n f l u e n c e o f smoking and d u s t e x p o s u r e . Tho rax 1982 ; 37 :760-764 8. Pa rkes WR: O c c u p a t i o n a l Lung D i s o r d e r s London : B u t t e r w o r t h s , 1982 9 . W i l e s F J , F au re MH, S l u i s - C r e m e r GK, VanDoorn HT, Wolek K: A p r e l i m i n a r y r e p o r t on a c o h o r t o f w h i t e g o l d m i n e r s . I n : S h a p i r o HA e d , P n e u m o c o n i o s i s , Capetown: O x f o r d U n i v e r s i t y P r e s s , 1970:350-351 - 184 -10 . Erasmus LD , VanDoorn H: Pu lmonary d i s a b i l i t y and pu lmonary f u n c t i o n i n g o l d m i n e r s on the W i twa t e r sand r e l a t e d t o d u r a t i o n o f s e r v i c e . I n : S h a p i r o HA e d , P n e u m o c o n i o s i s , Capetown: , O x f o r d U n i v e r s i t y P r e s s , 1970:417-421 1 1 . W i l e s F J , F au re MH: C h r o n i c o b s t r u c t i v e l u n g d i s e a s e i n g o l d m i n e r s . I n : Wa l ton WH, e d , I n h a l e d P a r t i c l e s IV . O x f o r d : Pergamon P r e s s , 1977:727-734 12 . Love RG, M i l l e r BG: L o n g i t u d i n a l s t udy o f l u n g f u n c t i o n i n c o a l m i n e r s . Thorax 1982: 37 :193-7 1 3 . C r a i g h e a d J , Abraham J , Churg A , Green F, K l e i n e r m a n J , Seemayer T , V a l l y a t h a n V , W e i l l H: The p a t h o l o g y o f a s b e s t o s - a s s o c i a t e d d i s e a s e s o f the l u n g s and p l e u r a l c a v i t i e s : d i a g n o s t i c c r i t e r i a and p r o p o s e d g r a d i n g schema. A r c h P a t h o l Lab Med 1982 ; 106:541-595 14 . P e r e s s L, Hoag H, Whi te F, B e c k l a k e MR: The r e l a t i o n s h i p between c l o s i n g vo l ume , smok ing , and a s b e s t o s d u s t e x p o s u r e . C l i n Res 1975 ; 111 :647A 1 5 . R o d r i q u e z - R o i s i n R, Merchant JA , Cochrane GE , H i c k e y BPH: Max ima l e x p i r a t o r y f l o w volume c u r v e s i n worke rs exposed t o a s b e s t o s . R e s p i r a t i o n 1980 ; 39 :158-165 16 . Seeker-Wa lke r RH, Ho J E : R e g i o n a l l u n g f u n c t i o n i n a s b e s t o s w o r k e r s . R e s p i r a t i o n 1982 ; 43 :8-22 17 . Kauffmann F, D roue t D, L e l l o u c h J , B r i l l e D: O c c u p a t i o n a l exposu re and 12-yea r s p i r o m e t r i c changes among P a r i s a r e a w o r k e r s . Br J Ind Med 1982 ; 39 :221-232 18 . Morgan WKC: I n d u s t r i a l b r o n c h i t i s . Br J Ind Med 1978 ; 35 :285-291 - 185 -1 9 . Sea ton A : C h r o n i c b r o n c h i t i s and c o a l m i n i n g i n the U n i t e d K ingdom. Eu r J Resp D i s 1982 ; Supp l 118 :53-57 20 . Ba tes DV, WooIf CR, P a u l , G I : C h r o n i c b r o n c h i t i s : a r e p o r t on the f i r s t two s t a g e s o f the c o o r d i n a t e d s t udy o f c h r o n i c b r o n c h i t i s i n the Depar tment o f V e t e r a n s A f f a i r s , Canada . Med Se r v J Can 1962 ; 18 :211-303 21 . ILO U/C 1971 I n t e r n a t i o n a l c l a s s i f i c a t i o n o f r a d i o g r a p h s o f the pneumocon ioses . M e d i c a l Rad iog raphy and Pho tog raphy 1972 ; 48 :67-76 22 . M a n f r e d a J , S i d w a l l G, M a i n i K, West P, C h e r n i a k RM: R e s p i r a t o r y a b n o r m a l i t i e s i n employees o f the h a r d r o c k m i n i n g i n d u s t r y . Am Rev R e s p i r D i s 1982 ; 126:629-634 23 . Pham QT, M a s t r a n g e l o G, Chaw N, H a l u s k a J : F i v e y ea r l o n g i t u d i n a l c o m p a r i s o n o f r e s p i r a t o r y symptoms and f u n c t i o n i n s t e e l worke r s and unexposed w o r k e r s . B u l l Eu r P h y s i o p a t h o l R e s p i r 1979 ; 15 :469-480 24 . C o l l i n s J F , O r o z c o CR, M c C u l l o u g h B, C o a l s o n J J , Johanson J r . W . G . : Pu lmonary f i b r o s i s w i t h s m a l l a i rway d i s e a s e : a mode l i n non-human p r i m a t e s . Expe r Lung Res 1982 ; 3 :91-108 2 5 . Rae S, Wa lker DD, A t t f i e l d M: C h r o n i c b r o n c h i t i s and d u s t exposu re i n B r i t i s h c o a l m i n e s . I n : Wa l ton WH e d , I n h a l e d p a r t i c l e s I I I O l d Wok ing . Unwin B r o s , 1971 : 883-894 26 . G a e n s l e r EA , C a r r i n g t o n CB, Cou tu RE , Tomas ian A , Hoffman L, Smi th AA: P a t h o l o g i c a l , p h y s i o l o g i c a l , and r a d i o l o g i c a l c o r r e l a t i o n s i n the pneumocon ioses . Ann NY Acad S c i 1972 ; 200:574-607 - 186 -27 . W i l e s F J , F au re MH: C h r o n i c o b s t r u c t i v e l u n g d i s e a s e i n g o l d m i n e r s . I n : Wa l ton WH e d , I n h a l e d P a r t i c l e s IV . O x f o r d : Pergamon P r e s s , 1977:727-734 28 . He i tzman RE: The Lung R a d i o l o g i c - P a t h o l o g i c C o r r e l a t i o n s . S t . L o u i s : C . V . Mosby C o , 1973 29 . Rasche B, R e i s n e r MTR, I s l a m MS, T h i e l H, Zimmerman I, Baumann H, U lmer WT: I n d i v i d u a l f a c t o r s i n the deve lopment o f c o a l m i n e r s * p n e u m o c o n i o s i s . Ann Occup Hyg 1982 ; 26 :713-722 3 0 . Reger R, Hancock J , Hank inson J , H e a r l R, Merchan t J : C o a l m i n e r s exposed t o d i e s e l exhaus t e m i s s i o n s . Ann Occup Hyg 1982 ; 126:799-815 3 1 . S t a n e s c u DC, P i l o t L, G a v r i l e s c u N, T e c u l e s c u DB, C r i s t e s c u I: A s p e c t s o f pu lmonary mechan i c s i n a r c w e l d e r s ' s i d e r o s i s . Br J Ind Med 1967 ; 24 :143-147 - 187 -TABLE V I I Exposu re H i s t o r i e s M i n e r s 1. Copper >10 y e a r s 2. G o l d , C o a l , A s b e s t o s 18 y e a r s 3. Hard r o c k 30 y e a r s 4 . G o l d , L e a d / Z i n c , U r an i um , T u n g s t e n 32 y e a r s 5. G o l d >10 y e a r s 6. C o a l , G o l d 17 y e a r s 7. Q u a r t z 14 y e a r s 8. G o l d , Radium >10 y e a r s 9. L e a d / Z i n c , G o l d , Copper >10 y e a r s 10 . Hard Rock M i n i n g 11 y e a r s Q u a r r y i n g 22 y e a r s O t h e r M i n e r a l Dust/Fume Exposu re 1. I r o n Worker/Gas We lder >10 y e a r s 2. L e a d / Z i n c S m e l t e r ( A s b e s t o s E x p . ) 35 y e a r s 3. G r i n d e r >10 y e a r s 4 . Gas We lder ( A s b e s t o s E x p . ) 20 y e a r s 5. I r o n B l a s t Fu rnace O p e r a t o r 25 y e a r s 6. W e l d e r / S t e e l F a b r i c a t o r 36 y e a r s 7. I r o n B l a s t F u r n a c e / F o u n d r y >10 y e a r s 8. We lder >io y e a r s 9. M a c h i n i s t 34 y e a r s - 188 -T a b l e V I I I PULMONARY FUNCTION Exposed Workers Compared t o C o n t r o l s Exposed C o n t r o l s Age 62.3 + 10.3 62.4 + 10.6 C i g a r e t t e y e a r s 981.3 + 520.7 1020.2 + 488.2 n 19 19 Pu lmonary F u n c t i o n (% P r e d . ) TLC 110.9 + 17.1 108.4 + 14.2 FRC 134.1 + 32.0 124.1 + 18.8 RV 151.0 + 45.7 134.9 + 30.6 FEVx 86.4 + 19.6* 97.0 + 21.3 FEV i / FVC ( a c t u a l ) 66.6 + 10.5 72.1 + 8.1 Yso 45.4 + 29.9** 65.3 + 37.0 v 2 5 32.3 + 17.7** 48.7 + 27.3 i N 2 / L 446.9 + 331.7* 231.0 + 152.4 F r . uptake-CO 83.6 + 19.0 90.7 + 20.4 D i f f . c a p . - C O 80.4 + 34.8 88.7 + 30.9 (Mean + S .D . ) * p < 0.05 * * p < 0.01 Table IX MINERS COMPARED TO CONTROLS (X + SD) Tota l Group Heavy Smokers Only ( > 800 Cig. Yra.) Miners Controls Miners Controls Age Cigarette years 66.4 + 7.1 1095 + 618 66.7 + 5.8 1154 + 600 65.7 + 5.7 1403 + 519 66.2 + 5.4 1469 + 578 10 10 Pulmonary Function (% predicted) TLC FRC RV FEV X FEVj/FVC (actual) Y50 V 25 AN 2/L DL FU co CO 116.2 + 15.6 110.5 + 16.1 124.6 + 11.4 106.0 + 18.5 138.9 + 33.0 125.9 + 20.2 155.0 + 26.2 122.9 + 25.6** 166.3 + 47.4 138.3 + 29.2 188.6 + 41.6 134.1 + 35.3* 87.1 + 23.5 98.3 + 20.4 80.3 + 26.1 92.2 + 13.1 65.3 + 8.7 70.7 + 8.2 61.3 + 7.8 71.6 + 8.2* 41.9 + 21.0 59.6 + 26.0 31.6 + 17.2 58.6 + 25.6* 31.5 + 12.6 47.6 + 24.0* 26.2 + 9.8 44.7 + 22.0* 395.6 + 240.3 190.8 + 81.2 481.1 + 252.1 162.8 + 86.7* 83.3 + 19.6 99.1 + 36.3 78.3 + 46.0 81.9 + 11.0 84.2 + 19.6 99.6 + 18.6 76.7 + 17.4 94.8 + 9.8* *p< .05 **p£ .01 - 190 T a b l e X DUST/FUME compared t o CONTROLS (X + SD) Pu lmonary F u n c t i o n (% P r e d i c t e d ) Dust/Fume C o n t r o l s Age C i g a r e t t e y e a r s 57 .8 + 1 1 . 8 889 + 419 57 .6 + 1 2 . 9 849 + 283 TLC 104.2 + 17 .5 105 .7 + 1 2 . 0 FRC 127 .8 + 32 .1 121 .8 + 18 .1 RV 131 .5 + 3 7 . 9 130 .6 + 34 .2 FEVx 85 .5 + 1 5 . 0 9 5 . 3 + 2 3 . 9 FEV-j/FVC ( a c t u a l ) 68 .5 + 13.1 7 3 . 8 + 8.2 750 4 9 . 9 + 4 0 . 0 * 72 .7 + 49 .1 v 2 5 32 .2 + 23 .9 * 4 9 . 9 + 33 .1 A N 2 / L 524 .0 + 452 2 9 1 . 0 + 217 D L c o 76.7 + 2 0 . 0 75 .3 + 16 .1 F U „ n 8 2 . 8 + 1 9 . 8 79 .2 + 1 7 . 6 *p < .05 - 191 -T a b l e X I S m a l l A i rway P a t h o l o g y - Exposed v s . C o n t r o l s (X + SD) Exposed C o n t r o l s 19 19 Membranous B r o n c h i o l e s I n f l a m m a t i o n 32 .5 + 14 .7 32 .4 + 25 .1 F i b r o s i s 48 .3 + 21 .5 29 .5 + 1 4 . 2 * M u s c l e 35 .2 + 20 .2 31 .1 + 1 5 . 8 P igment 18 .6 + 11 .7 18 .0 + 1 0 . 6 G o b l e t C e l l M e t a p l a s i a 37 .7 + 21 .8 24 .8 + 2 0 . 7 * Squamous M e t a p l a s i a 13 .6 + 12 .6 14 .2 + 10 .6 T o t a l P a t h o l o g y S co r e 185 .9 + 55 .1 151 .1 + 4 2 . 5 * R e s p i r a t o r y B r o n c h i o l e s I n f l a m m a t i o n F i b r o s i s M u s c l e P igment I n t r a l u m e n a l Macrophages 30 .5 + 13 37 .7 + 12 1 3 . 8 + 9 3 2 . 9 + 18 2 1 . 8 + 9 9 8 7 1 6 . 8 25, 30, 17, 28, 22 7 + 1 1 . 3 1 + 9 . 2 * 6 + 13 .7 5 + 9 .3 2 + 13 .1 T o t a l P a t h o l o g y S co r e 136 .6 + 44 .2 124 .6 + 2 7 . 0 * p < 0 .05 - 192 -T a b l e X I I S m a l l A i rway P a t h o l o g y F i b r o s i s F i b r o s i s G o b l e t C e l l (Membr. B r . ) (Resp . B r . ) M e t a p l a s i a 37 .5 + 2 1 . 3 32 .1 + 12 .4 3 3 . 4 + 25 .2 + + 6 0 . 3 + 1 4 . 8 * * 4 4 . 0 + 1 0 . 8 * 3 8 . 0 + 2 2 . 3 * 3 3 . 3 + 17 .4 32 .1 + 7.4 28 .5 + 22 .2 3 0 . 8 + 11 .6 27 .9 + 1 0 . 8 20 .7 + 1 9 . 3 Dust/Fume > C o n t r o l s * p < .05 * * p <.005 Dust/Fume > M i n e r s + p <.05 (by compa r i son o f d i f f e r n c e s f rom r e s p e c t i v e c o n t r o l s ) - 193 -T a b l e X I I I R a d i o l o g y Pneumocon ios i s P o s s i b l e Dust Change No Dus t Change M i n e r s O t h e r Dust/Fume C o n t r o l s 0 0 3 1 5 15 Pneumocon ios i s Grade P 1/1, S 2/2 P 1/1 P 1/0, S 1/0 P 1/0. Ho P 1/0 P 1/1, S 1/1 P 1/1 Type o f Work Copper M i n i n g G o l d M i n i n g C o a l and G o l d M i n i n g Q u a r t z M i n i n g G o l d and Radium M i n i n g L e a d / Z i n c , G o l d , Copper M i n i n g Hard Rock M i n i n g & Q u a r r y i n g E a r l y Dust Changes I n t e r s t i t i a l F i b r o s i s Few Nodu l es F i b r o s i s - A n t . RUL I r o n Worker/Gas We lde r G r i n d e r L e a d / z i n c s m e l t e r Management - 194 -F i g u r e 13 (a) P o r t i o n o f a membranous b r o n c h i o l e f rom the l u n g o f a b l a s t f u r n a c e o p e r a t o r showing marked d i s t o r t i o n o f t he a r c h i t e c t u r e w i t h f i b r o u s c o n n e c t i v e t i s s u e (FCT) t h i c k e n i n g o f the a i rway w a l l as w e l l as i n f l a m m a t o r y c e l l i n f i l t r a t i o n ( I ) . (Hema toxy l i n and e o s i n ; bar=100/u). (b) R e s p i r a t o r y b r o n c h i o l e f r om the l u n g o f a s m e l t e r worke r w i t h dense f i b r o u s c o n n e c t i v e t i s s u e (FCT) t h i c k e n i n g and d i s t o r t i o n o f the w a l l . ( H e m a t o x y l i n and e o s i n ; bar=100/u). ( c ) H i g h e r m a g n i f i c a t i o n o f an a d j a c e n t p o r t i o n o f the a i rway shown i n ( a ) , i n d i c a t i n g numerous f i b r o b l a s t s (FB) and e x c e s s f i b r o u s c o n n e c t i v e t i s s u e . (Hema toxy l i n and e o s i n ; bar=10n) (d) S e c t i o n o f a membranous b r o n c h i o l e f rom the l u n g o f a l e a d / z i n c s m e l t e r worke r s t a i n e d w i t h P e r i o d i c a c i d - S c h i f f s t a i n (PAS) i n d i c a t i n g g o b l e t c e l l m e t a p l a s i a . The PAS p o s i t i v e g o b l e t c e l l s (which appear d a r k i n the pho tog raph ) a r e e x t r e m e l y numerous and a re seen a round the whole c i r c u m f e r e n c e o f the a i rway (ba r=100u ) . I n s e t : H i g h e r m a g n i f i c a t i o n o f the box i n d i c a t e d i n ( d ) , c l e a r l y showing the PAS p o s i t i v e g o b l e t c e l l s ( ba r=10u ) . - 195 -- 196 -F i g u r e 14 (a) R a d i o g r a p h o f d r i e d s l i c e f r om l u n g o f a m ine r whose p r e - o p e r a t i v e c h e s t r a d i o g r a p h i n d i c a t e d g rade P 1/1, S 1/1 pneumocon io s i s i n d i c a t i n g a r ea s where two t i s s u e b l o c k s w i l l be removed (1 ,2 ) and n o d u l a r d e n s i t y i n b l o c k one ( m ^ )• (b) Pho tog raph o f d r i e d s l i c e i n d i c a t i n g b l o c k s one and two removed f o r h i s t o l o g i c a l a s s e s s m e n t . ( c ) Pho tog raph o f h i s t o l o g i c a l s l i d e f rom b l o c k 1 f rom (a) a f t e r r e - i m m e r s i o n i n f i x a t i v e and s e c t i o n i n g , i n d i c a t i n g nodu l e c o r r e s p o n d i n g t o r a d i o g r a p h i c d e n s i t y . (d) Low power m i c r o g r a p h o f nodu l e shown i n (c ) i n d i c a t i n g w h o r l e d f i b r o s i s p a t t e r n t y p i c a l o f s i l i c o s i s ; ( H e m a t o x y l i n and e o s i n ; bar=lmm). - 197 -- 198 -Summary and C o n c l u d i n g Comments The s t u d i e s d e s c r i b e d i n the p r e c e d i n g c h a p t e r s were d e s i g n e d t o i n v e s t i g a t e the n a t u r e o f the i n f l a m m a t o r y p r o c e s s i n the a i r w a y s . In p a r t i c u l a r , q u e s t i o n s were asked r e l a t i n g to i t s e a r l y i d e n t i f i c a t i o n and i t s s t r u c t u r a l and f u n c t i o n a l m a n i f e s t a t i o n s and i m p l i c a t i o n s i n c i g a r e t t e smokers and t h o s e exposed t o wood and m i n e r a l d u s t . In summary, the r e s u l t s o f the i n v e s t i g a t i o n s c a r r i e d ou t i n c l u d e the f o l l o w i n g . F i r s t , the use o f r a d i o g a l l i u m t o \" l a b e l \" t he p o l y m o r p h o n u c l e a r i n f i l t r a t e seen i n the a i rways f o l l o w i n g c i g a r e t t e smoke exposu re does no t appear t o be a u s e f u l t e c h n i q u e f o r i d e n t i f i c a t i o n o f a i rway i n f l a m m a t i o n , p r o b a b l y because t h i s i s o t o p e b i n d s p r e f e r e n t i a l l y t o macrophages r a t h e r than p o l y m o r p h o n u c l e a r l e u k o c y t e s . A p o t e n t i a l r e l a t i o n s h i p between e p i t h e l i a l d i s r u p t i o n f o l l o w i n g c i g a r e t t e smoke o r o c c u p a t i o n a l a n t i g e n exposu re and enhanced a i rway r e a c t i v i t y was no t r u l e d ou t but no d i r e c t c o r r e l a t i o n was seen between i n c r e a s e d e p i t h e l i a l p e r m e a b i l i t y and n o n - s p e c i f i c a i rway r e a c t i v i t y , b o t h measured i n human s u b j e c t s by n o n - i n v a s i v e t e c h n i q u e s . F i n a l l y t he s t r u c t u r e - f u n c t i o n c o r r e l a t i o n s tudy i n d i c a t e d t h a t the p r o g r e s s i o n o f the i n f l a m m a t o r y p r o c e s s i n p e r s o n s exposed t o i n d u s t r i a l p o l l u t a n t s i n a d d i t i o n t o c i g a r e t t e smoke d i f f e r s f rom t h a t i n c i g a r e t t e smokers w i t h o u t d u s t exposu re and r e s u l t s i n a d d i t i o n a l f u n c t i o n a l and - 199 -s t r u c t u r a l a b n o r m a l i t i e s . In a d d i t i o n t o the c o n c l u s i o n s and s p e c u l a t i o n s put f o r w a r d i n t he s p e c i f i c d i s c u s s i o n s o f the t h r e e s e t s o f e x p e r i m e n t a l i n v e s t i g a t i o n s , some g e n e r a l comments can a l s o be made a r i s i n g f r om t h i s body o f work.. The i n f l a m m a t o r y p r o c e s s i n g u i n e a p i g a i rways f o l l o w i n g smoke i n h a l a t i o n i s i d e n t i f i a b l e m o r p h o l o g i c a l l y by a PHN i n f i l t r a t e wh i ch i n c l u d e s PMN's i n the a i rway lumena . T h i s i s a s s o c i a t e d w i t h an i n c r e a s e i n p e r m e a b i l i t y . I n c r e a s e d a i rway e p i t h e l i a l p e r m e a b i l i t y i n humans i s e a s i l y d e m o n s t r a t e d u s i n g r a d i o a c t i v e t r a c e r s but i f po lymorphs a re p r e s e n t on the a i rway s u r f a c e s i n t h e s e s u b j e c t s , l a b e l l i n g o f t h e s e by i n h a l a t i o n methods w i l l r e q u i r e a t r a c e r wh i ch s p e c i f i c a l l y marks t h e s e c e l l s a l o n e . P r e v i o u s r e s e a r c h has i d e n t i f i e d a i rway i n f l a m m a t i o n as t he e a r l y e ven t i n the p r o g r e s s i o n toward s i g n i f i c a n t s m a l l a i rway p a t h o l o g y . T h i s i n f l a m m a t i o n i s l i k e l y a l s o a s s o c i a t e d w i t h i n c r e a s e d a i rway p e r m e a b i l i t y and t h i s may be a f a c t o r wh i ch a l l o w s enhanced p e n e t r a t i o n o f i n j u r i o u s o r i r r i t a n t s u b s t a n c e s t h rough the a i rway e p i t h e l i u m . T h i s c o u l d r e s u l t i n the enhanced s t r u c t u r a l and f u n c t i o n a l changes seen i n the d u s t - e x p o s e d w o r k e r s . E p i t h e l i a l i n f l a m m a t i o n may a l s o p l a y a r o l e i n the enhancement o f a i rway r e a c t i v i t y bu t t h i s cannot be demons t r a t ed by a s s o c i a t i o n w i t h i n c r e a s e d p e r m e a b i l i t y , e i t h e r i n p e o p l e w i t h known i n c r e a s e d p e r m e a b i l i t y o r i n t hose w i t h a n t i g e n - a s s o c i a t e d i n c r e a s e d r e a c t i v i t y . Heasurement o f n o n - s p e c i f i c a i rway r e a c t i v i t y i n f u t u r e - 200 -s t r u c t u r e - f u n c t i o n c o r r e l a t i o n s t u d i e s may p r o v i d e a d d i t i o n a l i n f o r m a t i o n about i t s r e l a t i o n s h i p t o a i rway i n f l a m m a t i o n . In a d d i t i o n , the f u r t h e r i n v e s t i g a t i o n o f a i rway e p i t h e l i a l p e r m e a b i l i t y changes d u r i n g exposu re t o i n h a l e d i r r i t a n t s may r e v e a l changes wh i ch canno t be shown when p e r m e a b i l i t y and r e a c t i v i t y a re measured on s e p a r a t e o c c a s i o n s . F i n a l l y , t h i s work c l e a r l y r e v e a l s the p o t e n t i a l f o r the deve lopment o f f u n c t i o n a l and s t r u c t u r a l a b n o r m a l i t i e s i n the a i rways wh ich may a r i s e f rom a i rway i n f l a m m a t i o n , and u n d e r s c o r e s the impo r t ance o f e a r l y d e t e c t i o n o f the i n f l a m m a t o r y p r o c e s s i n t h e s e a i rways i n b o t h c i g a r e t t e smokers and i n p e r s o n s exposed t o s u b s t a n c e s i n t h e i r env i ronment wh i ch may p rovoke o r augment a i rway i n f l a m m a t i o n . Susan M. Kennedy PUBLISHED PAPERS: Kennedy SH. E lwood RK. Wiggs BJR, Pa re PD, Hogg J C . I n c r e a s e d r e s p i r a t o r y m u c o s a l p e r m e a b i l i t y o f smoke r s : R e l a t i o n s h i p t o a i r w a y r e a c t i v i t y . Am Rev R e s p i r D i s 1984 ; 1 2 9 : 1 4 3 - 1 4 8 . E lwood RK, Kennedy S, B e l z b e r g A , Hogg J C , Pa re PD. R e s p i r a t o r y m u c o s a l p e r m e a b i l i t y i n As thma . Am Rev R e s p i r D i s 1 9 8 3 ; 1 2 8 : 5 2 3 - 5 2 7 . W r i g h t J L , Lawson L, Pa re PD, Wiggs B, Kennedy S, Hogg J C . The m o r p h o l o g y o f p e r i p h e r a l a i rways i n c u r r e n t and e x - s m o k e r s . Am Rev R e s p i r D i s 1 9 8 3 ; 1 2 7 : 4 7 4 - 4 7 7 . PAPERS ACCEPTED FOR PUBLICATION: W r i g h t J L , Lawson LM, Pa re PD, Kennedy S, Wiggs B, Hogg J C . The d e t e c t i o n o f s m a l l a i rway d i s e a s e : A c o m p a r i s o n o f r o u t i n e and s p e c i a l f u n c t i o n t e s t s . Am Rev R e s p i r D i s 1984 ; a c c e p t e d f o r p u b l i c a t i o n . PAPERS SUBMITTED FOR PUBLICATION: Kennedy SM, W r i g h t J L , P i tman RG, M u l l e r JB , P a re PD, Hogg J C . S m a l l a i r w a y s t r u c t u r e - f u n c t i o n c o r r e l a t i o n i n p a t i e n t s w i t h m i n e r a l d u s t o r fume e x p o s u r e . S u b m i t t e d t o Am Rev R e s p i r D i s . ABSTRACTS PUBLISHED: Pa re PD, B rooks L A , C o p p i n CA , W r i g h t J L , Kennedy S, Wiggs B J , Hogg J C . D e n s i t y dependence o f maximal e x p i r a t o r y f l o w and a i rway p a t h o l o g y i n smoke r s . Am Rev R e s p i r D i s 1983 ; 1 2 7 : 2 5 2 . Kennedy S, Pa re PD, E lwood RK, Wiggs B, Hogg J C . Lung e p i t h e l i a l p e r m e a b i l i t y and a i rway r e a c t i v i t y i n smokers and non-smokers . Am Rev R e s p i r D i s 1 9 8 3 ; 1 2 7 : 2 5 2 . Kennedy SM, W r i g h t J L , Pa re PD, Hogg J C . S m a l l a i rways s t r u c t u r e and f u n c t i o n i n p e r s o n s exposed t o i n d u s t r i a l d u s t s and fumes . C a n a d i a n Lung A s s o c i a t i o n A n n u a l M e e t i n g , 1983 . "@en ; edm:hasType "Thesis/Dissertation"@en ; edm:isShownAt "10.14288/1.0096583"@en ; dcterms:language "eng"@en ; ns0:degreeDiscipline "Pathology"@en ; edm:provider "Vancouver : University of British Columbia Library"@en ; dcterms:publisher "University of British Columbia"@en ; dcterms:rights "For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use."@en ; ns0:scholarLevel "Graduate"@en ; dcterms:title "Airway response to inhaled air pollutants--cigarette smoke & industrial dust & fume"@en ; dcterms:type "Text"@en ; ns0:identifierURI "http://hdl.handle.net/2429/25592"@en .