Cytochromes P-450 in murine lung. An immunohistochemical study with monoclonal antibodies.

We have used a panel of monoclonal antibodies (Mabs) and immunofluorescence to investigate the distribution of species of cytochrome P-450 inducible by 3-methylcholanthrene (3-MC) and phenobarbital (PB) in the lungs of "responsive" C57BL/6 and "nonresponsive" DBA/2 mice. A Mab (1-7-1) specific for an epitope common to rat cytochromes P-450c (P450IA1) and P-450d (P450IA2) detected the corresponding murine species (P1-450/P3-450) in cells of the alveolar septa, including type II cells, as well as endothelial cells lining blood vessels. Cytochrome P1-450 (Mabs 1-31-2, 1-36-1) is localized in type II cells of the alveolar septa but is not found in endothelial cells. Patterns of immunoreactivity with the 3-MC-specific Mabs indicate that alveolar septal cells possess P1-450 and P3-450, whereas endothelial cells of the vasculature are not the sites of P1-450, but rather of P3-450. Similar immunoreactivities for the 3-MC-defined P-450s are demonstrated in the lungs of C57BL/6 and DBA/2 mice. A Mab (2-66-3) which recognizes P-450b/P-450e (P450IIB1/P450IIB2) is reactive with P-450s localized in type II alveolar and bronchiolar epithelial cells, including nonciliated Clara cells. The epitope for cytochromes P-450b/P-450e is present in constitutive form within the lung and does not appear to be responsive to induction by PB. In contrast, epitopes for P1-450/P3-450 and P1-450 are not expressed constitutively but are only detected when induced by 3-MC.(ABSTRACT TRUNCATED AT 250 WORDS)