Serum immune complexes and disease.

The solid phase Clq radioimmunoassay was used to detect immune complexes in sera from patients with systemic lupus erythematosus (14/25), rheumatoid arthritis (4/5), vasculitis (5/15), infective endocarditis (2/2), acute rheumatic fever (2/3), pre-eclamptic toxaemia (0/14), lung cancer (3/7), glomerulonephritis (26/98) and renal transplant patients (0/5). The best correlation with disease activity was seen in systemic lupus erythematosus and infective endocarditis where serial immune complex determinations were clearly of value in monitoring therapy. The findings in primary glomerulonephritis indicate only a limited usefulness of the assay in that serum immune complexes were detected in a minority (22/73) of patients with glomerular immune deposits. In particular the data do not support a role for Clq fixing immune complexes in the pathogenesis of membranous glomerulonephritis or in pre-eclamptic toxaemia.