Cytochrome P-450 localization in normal human adult and foetal liver by immunocytochemistry using a monoclonal antibody against human cytochrome P—450

Abstract

Immunocytochemical studies with a monoclonal antibody (MAb—HL3), which recognises a major isozyme of human hepatic cytochrome P—450, have demonstrated this cytochrome in both cryostat and formalin-fixed paraffin-embedded sections of normal human adult liver. Prior trypsin digestion of the formalin-fixed sections prevented staining. There was a zonal distribution of immunoreactive cytochrome P—450, with localization predominantly in the hepatocytes of zone 3 of the hepatic acinus (the centrilobular region). Cytochrome P—450 was also demonstrated in foetal liver, but all foetal hepatocytes contained immunoreactive cytochrome P—450 and there was no zonal distribution of the protein. The biliary epithelium of adult liver contained a small amount of immunoreactive cytochrome P—450 whereas there was no immunoreactivity in the epithelium of foetal bile ducts.