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Abstract

Particulate matter (PM) deposited into the lung is removed predominantly by ciliary action of epithelial cells in the airways and by macrophages that phagocytose these particles in the peripheral air space. We hypothesize that the particle load or burden in the lungs’ of patients with Chronic Obstructive Pulmonary Disease (COPD) are responsible for perpetuating the chronic inflammatory response in the lung of subjects with COPD (even after smoking cessation). Samples were selected to cover the whole range of severity of COPD. Quantitative histological methods were used to quantify and characterize the particle burden in the lung tissue. The volume fraction (Vv) of PM in the lung tissue, including the parenchyma, airways, alveolar macrophages, blood vessels, and lymphoid follicles was determined using the aforementioned methods. To determine the chemical composition of the PM, Raman spectroscopy was used to analyze samples in situ. PM could be found in virtually all compartments of the lung: the parenchyma, blood vessels, airways, lymphoid follicles, and alveolar macrophages. The total burden of PM in all tissues of the lung was higher in subjects with COPD compared to controls (p