Immunological Detection and Quantitation of DNA Adducts Formed by 4‐Aminoazobenzene Species in vivo

Antibodies to 3‐methoxy‐4‐aminoazobenzene (3‐MeO‐AAB) and 2‐methoxy‐4‐aminoazobenzene (2‐MeO‐AAB) DNA adducts were raised in rabbits against in vitro‐adducted DNA samples. The enzyme‐linked immunosorbent assay (ELISA) was used to determine the sensitivity and specificity of these antibodies. They proved highly specific for the modified DNA used as the immunogen, but cross‐reacted with each other. Moreover, they showed cross reactivity with DNA modified by 4‐(o‐tolylazo)‐o‐toluidine, but not by other carcinogens, such as 4‐aminobiphenyl or 4‐nitroquinoline 1‐oxide. The 50% inhibition level of antibody binding in the competitive ELISA was at 10–20 fmol of modified base per assay (equivalent to 1–2 adducts per 10(6) bases). Immunohistochemical staining indicated that these antibodies bind specifically to nuclear components of the liver in rats given either 3‐MeO‐AAB or 2‐MeO‐AAB at the dose of 50 mg/kg body weight.