Anti-DNA, antihistone, and antinucleosome antibodies in systemic lupus erythematosus and drug-induced lupus

Anti-DNA antibodies play a crucial part in the pathogenesis of disease symptoms of SLE. Low avidity anti-DNA antibodies also occur in rheumatic diseases other than SLE. The Farr assay, which detects high avidity anti-DNA antibodies, is useful in helping to diagnose SLE. The optimal screening procedure is ELISA or Crithidia test, followed by confirmation of Farr assay. Use of a quantitative assay selective for high avidity anti-DNA antibodies is very valuable in the monitoring of individual SLE patients; measurements of anti-DNA antibodies should be performed every 4–6 wk. The results show a relation between low avidity anti-DNA antibodies and central nervous system involvement, and high avidity anti-DNA antibodies and nephritis. A significant rise in anti-DNA antibodies may correlate with a clinical relapse. All relapses are preceded by a prominent rise in anti-DNA antibodies as determined by Farr assay. A dramatic drop of anti-DNA antibody levels directly precedes the relapse; this phenomenon might be due to a concurrent immune deposit formation.