Analysis of polyethylene glycol precipitates from SLE sera: antibody enrichment in association with disease activity

Twenty two systemic lupus erythematosus patients were assessed clinically for periods of up to six years. Polyethylene glycol precipitates of serial serum samples were analysed for the presence of autoantibodies by specific enzyme-linked immunoabsorbent assays. Increased enrichment of anti-Ro(SSA) was found to correlate with disease activity. Longitudinal studies of individual patients showed an association between disease exacerbation and enrichment of anti-Ro(SSA), anti-La(SSB) and anti-ssDNA. Circulating immune complexes isolated by anti-C3 affinity chromatography were also found to contain anti-Ro(SSA), anti-La(SSB) and anti-ss DNA and fixation of complement by complexes could be demonstrated. Enrichment of these autoantibodies in renal eluates of two patients with diffuse proliferative glomerulonephritis provided further evidence for a pathogenic role of these immune complexes.