Mixed function oxidase (MFO) systems consist of three components: cytochrome P-450 (P-450), NADPH-P-450 reductase and phospholipid. The P-450s are key components of MFO systems. A subtype of P-450, IA2 (P-450d in rat and P-450 LM4) specifically activates aromatic amines to extremely carcinogenic hydroxy compounds. In order to study the role of P-450 IA2, Balb/c mice were immunized with rat liver microsomal P-45OIA2 and rabbit microsomal cytochrome P-45OLM4. Four hybridomas were generated by fusion of myeloma cells with spleen cells from mice immunized with rat P-450 IA2. One of the hybridomas produced an IgGl type of monoclonal antibody (MAb) and three hybridomas produced IgM types. The latter IgM type MAbs specifically bound to P-450 IA2 and distinguished P-45OIA2 from P-45OIA1. The former MAb IgGl type bound to P-45OIA2 but also cross-reacted with P-450 IIE1 (P450j) and some P-450s in uninduced rat liver microsomes. P-450IIE1 also metabolizes N-nitrosodimethylamines. More than twenty hybridomas were generated by the fusion of myeloma cells with spleen cells from the mice immunized with rabbit P-45OLM4 and they produced various mouse immunoglobulin subtypes. These MAbs would be very useful for differentiating P-45OIA2 from P-45OIAI which activates aromatic hydrocarbons such as benzo(a)pyrenes. The differentiation of P-450s involved in carcinogen activation should be very important for understanding the mechanism of human carcinogenesis with respect to diets and environmental carcinogens.
