Antigen binding characteristics of experimentally-induced antibodies against hydroxyl radical modified native DNA

Hydroxyl radical, generated by UV irradiation of hydrogen peroxide caused d amage to native calf thymus DNA leading to strand breaks, base modification and decrease in melting temperature. The ROS-DNA was highly immunogenic in goat. The antibody activity was inhibited to the extent of 89% with the im munogen as inhibitor. Antigenic specificity of anti-ROS-DNA antibodies by c ompetition ELISA showed multiple cross-reactivity, recognizing B-, A- and a llied conformations. The immune complex formation with native and ROS-DNA w as substantiated by band shift assay. A striking observation, is the enhanc ed recognition of ROS-thymine and ROS-poly(dT) by the induced antibodies. T hese investigations suggest that ROS might be the plausible candidate for t he presentation of unique epitopes on ROS-DNA, in particular of thymine, in ducing antibodies cross-reacting,vith native DNA and play an important role in the pathogenesis of SLE.