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Airway response to inhaled air pollutants--cigarette smoke & industrial dust & fume Kennedy, Susan Marguerite 1984

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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. 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N iden AH , M i s h k i n F S , Khurana M: G a l l i u m - 6 7 c i t r a t e l u n g s cans i n i n t e r s t i t i a l l u n g d i s e a s e . Ches t 1976 ; 6 9 : 2 6 6 : 2 6 8 51 . S iemsen JK , Grebe SF , S a rgen t EN , Wentz D: G a l l i u m - 6 7 s c i n t i g r a p h y o f pu lmonary d i s e a s e s as a complement t o r a d i o g r a p h y . R a d i o l o g y 1976 ; 118:371-375 52 . Beaumont D, H e r r y JY , Sapene M, Bourque t P, L a r z u l J J , DeLaba r the B: G a l l i u m - 6 7 i n the e v a l u a t i o n o f s a r c o i d o s i s : c o r r e l a t i o n s w i t h serum a n g i o t e n s i n - c o n v e r t i n g enzyme and b r o n c h o a l v e o l a r l a v a g e . Tho rax 1982 ; 37 :11-17 - 100 -53 . S choenbe rge r C I , L i n e BR, Keogh BA, H u n n i n g l a k e GW, C r y s t a l RG: Lung i n f l a m m a t i o n i n s a r c o i d o s i s : compa r i son o f serum a n g i o t e n s i n - c o n v e r t i n g enzyme l e v e l s w i t h 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 - 6 7 s c a n n i n g assessment o f the T- l ymphocy te a l v e o l i t i s . Tho rax 1982 ; 37 :19-25 54. L i n e BR, H u n n i n g l a k e GE , Keogh BA, Jones E, J o h n s t o n GS, C r y s t a l RG: G a l l i u m - 6 7 s c a n n i n g t o s t age the a l v e o l i t i s o f s a r c o i d o s i s : c o r r e l a t i o n w i t h c l i n i c a l s t u d i e s , pu lmonary f u n c t i o n s t u d i e s , and b r o n c h o a l v e o l a r l a v a g e . Am Rev R e s p i r D i s 1981 ;123 :440-446 55 . J a v a h e r i S, L e v i n e BW, McKus i ck KA: S e r i a l ^ G a l u n g s c a n n i n g i n pu lmonary e s o i n o p h i l i c g r anu loma . Thorax 1979 ; 34 :822-823 56 . B e g i n R, Lamorueaux G , C a n t i n A , B i s s o n G, Masse S: D e t e c t i o n o f a l v e o l i t i s i n a s b e s t o s w o r k e r s . Am Rev R e s p i r D i s 1 9 8 3 ; 127 :94 57 . L i n e BR, Fu lmer JD , Reyno lds HY, Robe r t s WC, Jones A E , H a r r i s EK, C r y s t a l RG: G a l l i u m - 6 7 c i t r a t e s c a n n i n g i n the s t a g i n g o f i d i o p a t h i c pu lmonary f i b r o s i s : c o r r e l a t i o n w i t h p h y s i o l o g i c and m o r p h o l o g i c f e a t u r e s and b r o n c h o a l v e o l a r l a v a g e . Am Rev R e s p i r D i s 1978 ; 118:355-365 58 . Hunninghake GW, L i n e BR, S z a p i e l SV, C r y s t a l RG: A c t i v a t i o n o f i n f l a m m a t o r y c e l l s i n c r e a s e s the l o c a l i z a t i o n o f g a l l i u m - 6 7 a t s i t e s o f d i s e a s e . C l i n Res 1981 ; 29 :171A 59 . B a i l e EM, Nelems JMB, S c h u l z e r M, Pare PD: Measurement o f r e g i o n a l b r o n c h i a l a r t e r i a l b l o o d f l o w and b r o n c h o v a s c u l a r r e s i s t a n c e i n d o g s . J A p p l P h y s i o l 1982 ; 53:1044-1049 - 101 -6 0 . S iman i AS , Inoue S, Hogg J C : P e n e t r a t i o n o f the r e p i r a t o r y e p i t h e l i u m o f g u i n e a p i g s f o l l o w i n g exposu re t o c i g a r e t t e smoke Lab I n v e s t 1974 ; 31 :75-80 6 1 . 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 62 . L o u r e n c o RV, K l i m e k 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 63 . 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 64 . Boat T F , Cheng PW: B i o c h e m i s t r y o f a i rway mucous s e c r e t i o n s . Fed P roc 1980 ; 39 :3067-3074 6 5 . Swa r t zend rube r DC, Idoyaga-Vargas NL : 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 p e r i t o n e a l c e l l s by 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 . I n : A r ceneaux CG , e d , P r o c e e d i n g s o f 3 1 s t A n n u a l M e e t i n g o f  E l e c t r o n M i c r o s c o p y S o c i e t y o f A m e r i c a . 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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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 <L.001 N.S. N.S. N.S. (smokers vs. non-smokers) •comparison o f RI with and without beta-blockade: non-smokers: p<.01 smokers: p C 05 a l l subjects: p<.001 - 163 -T a b l e V S u b j e c t C h a r a c t e r i s t i c s and A n t i g e n Response - S tudy 2 Age B a s e l i n e P r e - C h a l l e n g e P o s t - C h a l l e n g e F E V X P C 2 0 PC 2o (%pred) (mg/ml) (mg/ml) Responders (n=4) x 49 .2 8 6 . 8 1.25 0 .71 SD 19 .2 9.2 1.06 0 .26 Non- responde r s (n=5) x 45 .2 74 .4 5.32 9 .80 SD 14 .1 23 .9 6.11 8 .49 T o t a l g roup 5 4 7 . 0 7 9 . 9 * 3.51 5.76 SD 15 .6 1 9 . 0 4 .87 7.68 * FEV3A.compared t o s u b j e c t s i n s t udy 1 (p < .001) T a b l e V I  P e r m e a b i l i t y Da t a - S tudy 2 B e f o r e C h a l l e n g e A f t e r C h a l l e n g e t 1 / 2 PI10 PI25 P I 4 5 t l / 2 P I10 " 2 5 P I 4 5 Responders (n=4) x 59 .4 7.0 10 .6 14 .7 71 .0 4 .3 8 .4 12 .1 SD 11 .4 7.4 8 .6 8.6 1 2 . 8 2.7 3.6 4 . 3 Non- responde r s (n=5) x 55 .1 9.3 1 4 . 3 2 2 . 0 7 2 . 0 * 7.3 11 .6 15 .1 SD 18 .6 4 . 9 8.3 9 .6 13 .2 3.1 4 .2 5.7 T o t a l g roup x 5 6 . 9 1 " 8 .3 12 .7 18 .6 SD 15.1 5.8 8.1 9.5 * t l / 2 ( t o t a l and t l / 2 (non-resp ) /•tl/2 ( t o t a l ) S tudy 2 s u b j e c t s < + \ tl/2 ( t o t a l ) S tudy 2 s u b j e c t s > 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 . 

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