Monoclonal antibodies to DNA modified by 8-methoxypsoralen and ultraviolet A light.

A panel of monoclonal antibodies have been developed which specifically recognize DNA modified by 8-methoxypsoralen (8-MOP) and ultraviolet A light (320-400 nm) (UVA). These antibodies have been characterized as to sensitivity and specificity by an enzyme linked immunosorbent assay (ELISA). In a competitive ELISA with the most sensitive antibody, 50% inhibition of antibody binding occurred at 17 fmole 8-MOP-DNA photo adducts. One adduct per 10(7) bases could be reliably detected. There was also some antibody cross-reactivity with DNAs modified by 4' aminomethyl-4, 5, 8-trimethylpsoralen and 4', 5-dimethylangelicin as well as DNA isolated from cells treated with 8-MOP and UVA. The primary specificity of one of the antibodies was shown to be the 4', 5' thymine monoadduct by competitive inhibition studies using HPLC fractions of an enzymatic digest of 8-MOP poly(dA-dT) . poly(dA-dT). These antibodies should allow the quantitation of adduct levels in various in vitro systems as well as humans exposed clinically to 8-MOP and UVA.