[Localization of cytochrome P-450PB in the rat liver and primary liver tumors of different histological structure after administration of inductor aroclor 1254].

Localization of cytochrome P-450PB in normal rat liver and primary liver tumors induced by DENA was studied by the immunoperoxidase method of unlabeled antibodies after treatment with a mixture of polychlorinated biphenyls (aroclor 1254). In intact liver, only one layer of the cells around the central veins was stained. On the 4th day after aroclor 1254 injection almost all the cells of the liver lobule were intensely stained. The ability for induction of cytochrome P-450PB was dramatically suppressed in the neoplastic nodules and trabecular carcinomas of the liver. The enzyme was detected only in individual groups of tumor cells whatever the level of their cytomorphological differentiation. In mixed tumors, the epithelium of the glandular component was inducible whereas the elements of the trabecular component were strongly but irregularly stained. No staining of tumor cells was recorded in the rats not treated with aroclor 1254.