A high frequency idiotypic marker of anti-DNA autoantibodies in MRL-Ipr/Ipr mice.

Anti-idiotypic antibodies were used to analyze relatedness of anti-DNA autoantibodies of MRL mice. The antiidiotypic antibodies, produced by immunization of rabbits with MRL-Ipr-derived hybridoma anti-DNA antibodies, were defined by their ability to inhibit specifically the binding of hybridoma anti-DNA antibody to DNA. One monoclonal anti-DNA antibody, H130, cross-reacted with two thirds of other hybridoma anti-DNA antibodies. The H130/anti-H130 system detected high amounts (up to 5 mg/ml) of immunoreactivity in sera of MRL-Ipr mice, whereas levels in MRL-+ sera were relatively low. The H130 family increased 10-fold in MRL-Ipr mice over the course of 5 mo, but its levels did not correlate chronologically with those of anti-DNA antibodies, cardiolipin-binding antibodies, or total serum immunoglobulins. H130 cross-reactivity was found, by quantitative immunoadsorption, in 40 to 60% of serum anti-DNA antibodies; however, a large excess of H130-related serum antibodies did not bind to DNA. The H130 family and anti-DNA antibodies therefore seem to constitute overlapping populations.