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

Hydroxyl radical, generated by UV irradiation of hydrogen peroxide caused damage 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 immunogen as inhibitor. Antigenic specificity of anti-ROS-DNA antibodies by competition ELISA showed multiple cross-reactivity, recognizing B-, A- and allied conformations. The immune complex formation with native and ROS-DNA was substantiated by band shift assay. A striking observation, is the enhanced recognition of ROS-thymine and ROS-poly(dT) by the induced antibodies. These investigations suggest that ROS might be the plausible candidate for the presentation of unique epitopes on ROS-DNA, in particular of thymine, inducing antibodies cross-reacting with native DNA and play an important role in the pathogenesis of SLE.