Human anti-DNA autoantibodies and induced antibodies against ROS-modified-DNA show similar antigenic binding characteristics.

Alterations in DNA structure by hydroxyl radical modification was characterized by UV spectroscopy, Tm, nuclease S1 digestibility and base modification. In view of indicted role of oxygen free radicals in human diseases, an attempt has been made to precisely compare the antigen binding properties of induced antibodies against hydroxyl radical modified DNA with those of naturally occurring anti-DNA autoantibodies. Antibodies induced against ROS-DNA showed diverse antigen binding characteristics which were comparable with those derived from SLE patients. The immune IgG recognized native DNA, heat denatured DNA, and synthetic polynucleotides in B-/B-like conformations. IgG isolated from SLE sera showed preference for ROS-DNA in competition-inhibition assay. The antigenic diversity of induced antibodies and preference of circulating anti-DNA autoantibodies for ROS-DNA over that of native DNA demonstrates the possible role of modified DNA antigens in the pathogenesis of SLE.