Heterogeneity of anti-dsDNA antibodies in their cross-reaction with ribosomal P protein.

We have investigated the possible cross-reaction of anti-dsDNA antibodies with ribosomal P peptide for several reasons. First, the antibodies frequently occur together, and secondly, they vary similarly with disease activity. Human polyclonal anti-dsDNA antibodies were affinity purified from eight patients and anti-ribosomal P antibodies from two patients with systemic Lupus erythematosus (SLE) who had high titers of anti-dsDNA as well as anti-ribosomal P antibodies. Nine of the 10 sera were totally specific in their reactivity with their cognate antigens. In only one patient did we find a subpopulation of antibodies which cross-reacted with both dsDNA and the carboxyl terminal 22 amino acid peptide. Our results indicate that anti-dsDNA antibodies are heterogeneous and usually do not cross-react with the carboxyl terminal P peptide, but on occasion (1/10) a patient will produce anti-dsDNA antibodies cross-reactive with the carboxyl terminal P peptide.