title: Monoclonal antibodies to phenobarbital-induced rat liver cytochrome P-450.
abstract: Somatic cell hybrids were made between mouse myeloma cells and spleen cells derived from BALB/c female mice immunized with purified phenobarbital-induced rat liver cytochrome P-450 (PB-P-450). Hybridomas were selected in HAT medium, and the monoclonal antibodies (MAbs) produced were screened for binding to the PB-P-450 by radioimmunoassay, for immunoprecipitation of the PB-P-450, and for inhibition of PB-P-450-catalyzed enzyme activity. In two experiments, MAbs of the IgM and IgG1 were produced that bound and, in certain cases, precipitated PB-P-450. None of these MAbs, however, inhibited the PB-P-450-dependent aryl hydrocarbon hydroxylase (AHH) activity. In two other experiments, MAbs to PB-P-450 were produced that bound, precipitated and, in several cases, strongly or completely inhibited the AHH and 7-ethoxycoumarin deethylase (ECD) activities PB-P-450. These MAbs showed no activity toward the purified 3-methylcholanthrene-induced cytochrome P-450 (MC-P-450), beta-naphthoflavone-induced cytochrome P-450 (BNF-P-450) or pregnenolone 16-alpha-carbonitrile-induced cytochrome P-450 (PCN-P-450) in respect to RIA determined binding, immunoprecipitation, or inhibition of AHH activity. One of the monoclonal antibodies, MAb 2-66-3, inhibited the AHH activity of liver microsomes from PB-treated rats by 43% but did not inhibit the AHH activity of liver microsomes from control, BNF-, or MC-treated rats. The MAb 2-66-3 also inhibited ECD in microsomes from PB-treated rats by 22%. The MAb 2-66-3 showed high cross-reactivity for binding, immuno-precipitation and inhibition of enzyme activity of PB-induced cytochrome P-450 from rabbit liver (PB-P-450LM2). Two other MAbs, 4-7-1 and 4-29-5, completely inhibited the AHH of the purified PB-P-450. MAbs to different cytochromes P-450 will be of extraordinary usefulness for a variety of studies including phenotyping of individuals, species, and tissues and for the genetic analysis of P-450s as well as for the direct assay, purification, and structure determination of various cytochromes P-450.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000918:Antibody Specificity; D001189:Aryl Hydrocarbon Hydroxylases / Q000032:analysis; D001564:Benzo(a)pyrene; D001580:Benzopyrenes / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis / Q000276:immunology*; D004790:Enzyme Induction / Q000187:drug effects; D005260:Female; D006825:Hybridomas; D008099:Liver / Q000201:enzymology*; D051379:Mice; D008807:Mice, Inbred BALB C; D010634:Phenobarbital / Q000494:pharmacology*; D051381:Rats
chemical_list: D000911:Antibodies, Monoclonal; D001580:Benzopyrenes; D001564:Benzo(a)pyrene; D003577:Cytochrome P-450 Enzyme System; D001189:Aryl Hydrocarbon Hydroxylases; D010634:Phenobarbital