Localization of phenobarbital- and 3-methylcholanthrene-inducible cytochromes P-450 in mouse lung with monoclonal antibodies.

The cytochromes P-450 are key components of the mixed-function oxidase system responsible for the biotransformation of many foreign compounds to mutagens and carcinogens. In the present study, the distribution of these hemoproteins in frozen sections of mouse lung was determined immunohistochemically, using monoclonal antibodies (Mabs). Mab 1-7-1 is specific for 3-methylcholanthrene-inducible cytochromes P-450; this Mab reacted intensely with parenchymal cells, but not epithelial cells of pulmonary bronchioles of 3-methylcholanthrene-treated mice. Mab 1-7-1 did not react with pulmonary cells of either untreated or phenobarbital-treated mice. Mab specific for phenobarbital-inducible cytochromes P-450, Mab 2-66-3, reacted with parenchymal and bronchiolar epithelial cells in the lungs of phenobarbital-treated, 3-methylcholanthrene-treated, and untreated mice. The localization of constitutive and induced forms of cytochrome P-450 in different cells of the lung may provide insight into the mechanisms by which cell-specific damage and carcinogenicity are evoked by xenobiotics.