Monoclonal antibodies (MAbs) have been successfully used for the investigation of the properties and diversity of human cytochrome P450s. For this purpose, cross-reacting Mabs which were developed against rat P450s have been used in the studies of human P450s. This research project is aimed at developing anti-human P-450 MAbs using baculovirus cDNA-expressed proteins. Initially, inhibitory and non-inhibitory MAbs against human P-450 2E1 and 3A4 were developed. It has been known that these two P450s are responsible for the metabolic activation of procarcinogens. Eleven hybrids producing mouse IgG against human 2E1 were selected. All MAbs reacted actively in ELISA with 2E1baculo but had comparatively low cross-reactivity with 2E1vaccinia, whereas in WB, nine of the eleven MAbs actively reacted with both 2E1baculo and 2E1vaccania. The property of the new Mabs allows us to use them for 2E1 screening in human populations although these MAbs did not show inhibitory effects on the P450 enzyme activity. Fifteen hybrids producing IgG against human 3A4 were developed. At least one MAb (275) reacted strongly in WB with 3A4baculo as well as with 3A4vaccinia. One MAb (3-29-9) showed up to 80% inhibition of testosterone metabolism by vaccinia-expressed 3A4 and another two MAbs exhibited 30-40% inhibition of the same substrate.
