Production and immunochemical characterization of a high-affinity monoclonal antibody specific for 7-(benzo[a]pyren-6-YL)guanine (BP-6-N7GUA), a depurinating DNA adduct of benzo[a]pyrene

Molecular dosimetry of depurinating DNA adducts of benzo[a]-pyrene (BP) offers a promising new approach to determining risk of PAH-induced cancer. Depurinating adducts are the predominant form of BP-induced DNA damage, are excreted in urine and, importantly, are linked to cancer initiation. We have produced a monoclonal antibody (MAb) with high specific affinity for BP-6-N7Gua, a major depurinating DNA adduct of BP, and have developed a sensitive and specific competitive enzyme-linked immunosorbent assay (ELISA). The I50s (quantity producing 50% inhibition of MAb binding in the ELISA) of selected BP adducts and metabolites were determined. The results indicated 1) a high degree of discrimination between BP-6-N7Gua (I50 = 750 fmol) and BP (I50 = 900,000 fmol), 2) high affinity of the MAb for BP-6-N7Ade (I50 = 1,500 fmol), another major depurinating DNA adduct, and 3) specific structural requirements for MAb-adduct binding. In addition, the competitive ELISA provided an accurate determination of BP-6-N7Gua added to normal human urine, at a sensitivity of 200 fmol.