Analysis of autoantibody specificities in selected systemic lupus erythematosus (SLE) sera.

In order to design effective diagnostics for lupus, the heterogeneity in patient response must be understood. This heterogeneity in the anti-Sm and anti-U1-RNP response was examined via a frequency analysis of autoantibody fine specificities. Thus, 275 sera were studied by immunoprecipitation, immunoblotting, and immunodiffusion, and the frequency of occurrence of different autoantibodies to individual snRNP polypeptides and to other HeLa cell polypeptides was determined. The sera were found to contain autoantibodies reactive with denatured as well as native forms of HeLa-cell polypeptides. The common occurrence of several novel antibody fine specificities was noted, such as anti-p45 (different from anti-La/SS-B), anti-p105, and anti-p115. Another group of autoantibodies that is apparently not disease associated was observed in both lupus and normal sera.