Molecular weight of circulating immune complexes in patients with glomerulonephritis

The Clq-binding test was used to detect circulating immune complexes in 86 patients with glomerulonephritis at the time of renal biopsy. By gel filtration of the sera it was possible to estimate the molecular weight in 24 of these patients. The molecular weight of circulating immune complexes varied from 150,000 to above 1.2 X 10(6) and was not related to the type of glomerulonephritis as defined by light microscopy, renal function, proteinuria, hematuria or antecedent infections. In 8 patients with rheumatoid arthritis and in 5 patients with secondary syphilis and no evidence or renal disease, only circulating immune complexes with a molecular weight below 1.2 X 10(6) were detected. 7 patients with glomerulonephritis had electron-dense deposits in glomeruli on electron microscopy, but the molecular weight of circulating immune complexes was not related to the site of the deposits on either side of the basement membrane.