title: Monoclonal antibody-directed determination of cytochrome P-450 types expressed in a human lymphoblastoid cell line.
abstract: Cytochrome P-450-dependent aryl hydrocarbon hydroxylase (AHH) and 7-ethoxycoumarin O-deethylase activities of a cloned line of human lymphoblastoid AHH-1 cells are inhibited by a monoclonal antibody (MAb 1-7-1) prepared to a 3-methylcholanthrene-induced rat liver cytochrome P-450. The monoclonal antibody inhibition determined that a single MAb 1-7-1-sensitive type of cytochrome P-450 is responsible for all of AHH expression in both the basal and benz[a]anthracene-induced cells. Partial inhibition by the MAb 1-7-1, however, indicates that at least two forms of cytochrome P-450 catalyze 7-ethoxycoumarin O-deethylase in both the basal and the induced cells, one form of which is identical to the MAb-sensitive cytochrome P-450 responsible for all of the AHH. Thus, a single cloned cell line is capable of expressing two classes of cytochromes P-450, and the observed multiplicity of cytochrome P-450 in animal tissues does not necessarily depend on cell heterogeneity. A sensitive MAb 1-7-1-based radioimmunoassay also directly demonstrates the presence in these cells of a MAb 1-7-1-specific type of cytochrome P-450 as well as its elevation in the induced cells. These MAb-based methods thus can determine the contribution of specific MAb-defined types of cytochromes P-450 to the cellular metabolism of specific xenobiotics.
mesh_terms: D015660:7-Alkoxycoumarin O-Dealkylase; D000818:Animals; D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism*; D001551:Benz(a)Anthracenes / Q000494:pharmacology; D002460:Cell Line; D002999:Clone Cells; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008214:Lymphocytes; D008748:Methylcholanthrene / Q000494:pharmacology; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism; D010105:Oxygenases / Q000378:metabolism*; D011863:Radioimmunoassay; D051381:Rats
chemical_list: D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D001551:Benz(a)Anthracenes; D008748:Methylcholanthrene; D003577:Cytochrome P-450 Enzyme System; C030935:benz(a)anthracene; D010105:Oxygenases; D015660:7-Alkoxycoumarin O-Dealkylase; D001189:Aryl Hydrocarbon Hydroxylases