COMPARISON OF VARIOUS IMMUNOCHEMICAL ASSAYS FOR THE DETECTION OF ETHYLENE-OXIDE DNA-ADDUCTS WITH MONOCLONAL-ANTIBODIES AGAINST IMIDAZOLE RING-OPENED N7-(2-HYDROXYETHYL)GUANOSINE - APPLICATION IN A BIOLOGICAL MONITORING STUDY

Monoclonal antibodies have been developed for the analysis of the pred ominant lesion in DNA induced by ethylene oxide (EtOx), namely N7-(2-h ydroxyethyl)guanine (N7-EtOHGua). Two monoclonal antibodies raised aga inst imidazole ring-opened N7- (2-hydroxyethyl)guanine (RON7-EtOHGua), N7EO-E and N7EO-11, and the previously isolated antibody N7E-102 were characterized by competitive ELISA with various inhibitors. N7EO-E an d N7EO-11 recognize 2-hydroxyethyl lesions better than ethyl or methyl lesions, while N7E-102 recognizes 2-hydroxyethyl and ethyl modificati ons equally well. All antibodies show a preference for imidazole ring- opened adducts, bind better to adducts in DNA compared to alkylated nu cleosides or bases and bind 10(6)- to 3 X 10(6)-fold less well to unmo dified DNA. The sensitivity of detection of RON7-EtOHGua in DNA and in the nuclei of cells in situ by antibody N7EO-E was investigated in se veral assays. The immunoslot blot assay was the most sensitive method (0.34 RON7-EtOHGua per 10(6) nucleotides was detectable), followed by competitive ELISA, direct ELISA and in situ detection by immunofluores cence microscopy. The immunoslot blot assay was used to analyse N7-EtO HGua levels in white blood cell DNA from individuals exposed to EtOx ( 2-5 p.p.m.) and of control. This exposure did not result in a statisti cally significant increase in the N7-EtOHGua level.