Kinetics of mucous cells in bronchial and bronchiolar epithelia during aerogenic elicitation with aspergillary proteins. A quantitative cytologic study.

During a prolonged exposure of rabbits to aerosols with asperigillary antigens, the content of bronchial and bronchiolar epithelia in mucus-secreting cells was quantified. In normals, the mucous cells do not exceed 3.2 per cent in bronchial epithelium and 0.44 per cent in bronchiolar one. After exposure, these proportions rapidly increase, after a primary discharge of goblet cells. The mucous cells become a majority after 7 exposures in bronchi and after 21 in bronchiolar epithelium. The maturation is more rapid in bronchioli than in bronchi. The secretion of neutral and acid mucopolysaccharides is early, concomitant in the same bronchus, and predominantly located in the impingement zones, especially the bifurcations of bronchial tree. The mitoses are extremely rare in exposed bronchi, but the epithelial and mesenchymal alveolar cells present a high mitotic index (1.14%) 24 hours after the second exposure to antigens.