Identification of cytochrome P-450 isozymes in nonciliated bronchiolar epithelial (Clara) and alveolar type II cells isolated from rabbit lung.

Two forms of cytochrome P-450 (P-450I and P-450II) have been shown by several techniques to be present in both nonciliated bronchiolar cells (Clara) and alveolar type II cells isolated from rabbit lung. In contrast, the alveolar macrophage contains little or none of these cytochromes. Cross-reactivity between antibodies to cytochrome P-450I or P-450II and detergent-digested microsomes prepared from 80% type II or 70% Clara cell fractions was shown by Ouchterlony double immunodiffusion. The presence of both cytochromes was also demonstrated by histochemical immunofluorescence in smears of type II cells stained by a modified Papanicolaou procedure and Clara cells stained with nitroblue tetrazolium. However, this same fluorescent antibody technique used for localization of rabbit pulmonary cytochromes P-450I and P-450II in tissue sections showed most of the immunofluorescence in the Clara cells of the bronchiolar epithelium. SDS-polyacrylamide gel electrophoresis of microsomes from either the type II or Clara cell fractions produced bands which corresponded to cytochrome P-450I (52,000 daltons) and cytochrome P-450II (58,000 daltons).