Cellular autofluorescent pigment and interstitial fibrosis in smoker's lung

The mechanisms by which cigarette smoking lead to bronchopulmonary diseases are incompletely understood. The most characteristic lesion is a chronic macrophage-alveolitis accompanied by slight fibrosis and emphysema. The macrophages contain a ceroid-like granular autofluorescent pigment in their lysosomes. Using immunohistochemical methods, open lung-, transbronchial biopsies and cells obtained by broncho-alveolar lavage from cigarette smokers were studied: anti-human macrophage serum and anti-human elastase, immune sera against type I, type III collagens and fibronectin were used in the demonstration of the cellular components of alveolitis and the connective tissue constituents of fibrosis. The characteristic red-brown autofluorescent pigment of the macrophages was also found in an extra-alveolar location mainly in peribronchial, septal and pleural scars. Similar emission colour occurred focally in the elastic laminae of fibrotic alveoli and sclerotic arteries. Granular fluorescent pigment was found in many bronchial epithelial cells. The epithelial pigmentation was associated with increased transcription of nucleic acid proteins, revealed by colloid silver (AgNOR) reaction. The results suggest that the autofluorescent pigment substances in macrophages may indicate or also play a role in the development of pathological connective tissue and epithelial changes of smoker's lung, in addition to the known mediators and enzymes.