Immunocytochemical studies of APUD cells in airways: effects of nitrosodiethylamine and nitrogen dioxide.

The amine precursor uptake and decarboxylase (APUD) cells and neuroepithelial bodies (NEBs) in airways of adult rats have been studied by immunocytochemical methods for the presence of adrenocorticotropic hormone (ACTH), growth hormone (hGH), calcitonin, and bombesin in control animals and following exposure to nitrosodiethylamine and nitrogen dioxide (NO2). Calcitonin-like immunoreactivity (CLIR) is present in APUD cells of the trachea and bronchioles and in NEBs in the lung. Rats treated with nitrosodiethylamine and NO2 exhibit increased numbers of argyrophilic cells but no increase in cells containing specific intracytoplasmic CLIR. The presence of ACTH, hGH, and bombesin in respiratory tract APUD cells was not observed. These studies indicate that APUD cells in the trachea and bronchioles of adult rats harbor endocrine cells with immunohistochemical characteristics similar to C cells of the thyroid, and that these cell do not appear to be altered in number when rats are treated with agents known to produce an increase in APUD cells.