Quantitation of exposure to benzo[a]pyrene with monoclonal antibodies

It is now possible to quantitate carcinogen adducts on DNA by highly sensitive immunoassays. These techniques are particularly useful for screening human populations for exposure to potential environmental carcinogens. We have developed a panel of monoclonal antibodies that react with benzo(a)pyrene (BP) modified DNA to be used in an enzyme linked immunoassay (ELISA) to quantitate adduct levels of both human and animal samples. BALBc/Cr mice were immunized with either DNA modified by 7β,8α-dihydroxy-9α,10α-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene (BPDE-I-DNA) complexed electrostatically to methylated bovine serum albumin or with BPDE-I-modified guanosine conjugated with bovine serum albumin (BPDE-I-G-BSA). Four stable clones were produced from the spleen cells of animals immunized with BPDE-I-DNA and one from BPDE-I-G-BSA immunized animals. All antibodies were shown to be highly specific for BPDE-I-DNA and did not crossreact with nonmodified DNA or with N-2-acetylaminofluorene or 1-aminopyrene modified DNA. The antibodies differed in their sensitivity to BPDE-II-DNA, BPDE-I-poly G, BPDE-I-tetraols and BPDE-I-dG. In general, all the antibodies showed the greatest affinity for their original antigen. Those generated against modified DNA showed highest reactivity against modified DNA while the one antibody generated against the monoadduct showed highest reactivity with the monoadduct. These antibodies are currently being used in a highly sensitive competitive ELISA to quantitate levels of BP-DNA adducts in various animal and human tissue samples.