Attenuated antigenicity of ribonucleoproteins modified by reactive oxygen species.

Ribonucleoprotein (RNP) particles isolated from fresh goat liver nuclei were exposed to hydroxyl radical which induced modification in the gross structure of RNP particles. To evaluate the effect of hydroxyl modification on the antigenic properties of RNP and possible role of ROS-RNP in the initiation and development of SLE, enzyme immunoassays were carried out. SLE sera having high titre anti-DNA antibodies showed enhanced binding to hydroxyl modified RNP particles in comparison to unmodified RNP particles. In competition assay none of the SLE sera or isolated IgG showed preference for ROS-modified RNP particles over native RNP particles. These studies suggest that anti-RNP autoantibodies observed in subpopulation of SLE patients are generated by some other intra-or extracellular mechanisms and hydroxyl radical has probably no direct role in the initiation of antibodies.