Anti-DNA antibody idiotypes in systemic lupus erythematosus.

Monoclonal anti-DNA antibodies prepared by the hybridoma technique were used for an analysis of idiotypes of anti-DNA antibodies in systemic lupus erythematosus (SLE). Serum levels of one idiotypic marker, 16/6/R, were higher than normal in 40 of 74 patients (54%) with active SLE, compared with only 6 of 24 patients (25%) with inactive SLE, 9 of 38 patients (25%) with rheumatoid arthritis, and 4 of 96 normal subjects (4%). Levels of the 16/6/R idiotypic marker were determined in serially collected serum samples from 12 patients with SLE. Concordance was found between idiotype levels and clinical activity in 8 of the 12 patients. Levels of the 16/6/R idiotype tended to correlate with levels of antibodies to double-stranded DNA, but in some cases the clinical status was reflected better by the idiotype levels than by the levels of anti-double-stranded-DNA antibodies. Measurement of idiotypes of anti-DNA antibodies may provide information valuable in monitoring the clinical course of patients with SLE.