Lupus serum and normal human serum contain anti-DNA antibodies with the same idiotypic marker.
We have previously shown that serum from patients with active SLE contain high levels of Id-16/6 and anti-DNA antibodies. In this study we investigated whether serum Id 16/6 is related to anti-DNA antibodies. Sera from 12 patients with active SLE were absorbed individually with poly(dT) cellulose (to purify anti-DNA antibodies) and rabbit (R) anti-Id-16/6 Sepharose (to purify Id 16/6 Ig). Removal of all anti-DNA activity removed most of the Id-16/6. Conversely, removal of all Id 16/6 removed most of the anti-DNA activity. Although there was no measurable anti-DNA antibody activity in normal serum, such antibodies were isolated by absorption with poly(dT) cellulose. The eluted immunoglobulins also had Id 16/6 activity. Similarly, Id 16/6 with anti-DNA activity were isolated from normal serum by absorption with R anti-Id 16/6 Sepharose. We conclude that a large fraction of anti-DNA antibodies in SLE serum are Id-16/6+, and that most Id 16/6 immunoglobulins in lupus serum have anti-DNA activity. Our observations suggest that lupus anti-DNA antibodies result from an overproduction of autoantibodies that are present in normal people.
D000936:Antigen-Antibody Complex; D001323:Autoantibodies / Q000032:analysis*; D004247:DNA / Q000276:immunology*; D006801:Humans; D007130:Immunoglobulin Idiotypes / Q000032:analysis*; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D012016:Reference Values
D000936:Antigen-Antibody Complex; D001323:Autoantibodies; D007130:Immunoglobulin Idiotypes; D004247:DNA