A longitudinal study of high and low avidity antibodies to double-stranded DNA in systemic lupus erythematosus.

The role of avidity in the pathogenicity of double-stranded DNA/anti-double-stranded DNA immune complexes in systemic lupus erythematosus (SLE) has been controversial. We used polyethylene glycol to identify low avidity antibodies and the standard Farr assay to detect high avidity antibodies against double-stranded DNA in a longitudinal study of sera from 19 patients with SLE. We found that high and low avidity antibodies to double-stranded DNA did not move independently, but instead, rose and fell in a parallel and relatively fixed manner in these patients. The mechanisms responsible for the changes in titer of anti-double-stranded DNA antibody appeared nondiscriminatory in regard to avidity. In addition, the humoral immune response in SLE depicted by these antibody measurements appeared atypical, lacking maturational features.