Platelet-aggregating immune complexes in idiopathic glomerulonephritis and SLE

Immune complex-like material with a molecular weight of greater than 500,000 Daltons was detected in the majority of sera from patients with idiopathic glomerulonephritis, as well as in systemic lupus. In the Raji cell and Clq binding assays the glomerulonephritis sera gave, in general, negative results. Patients with membranous nephropathy, minimal change disease and Henoch-Schönlein purpura also gave positive results in the platelet test, in agreement with other tests not dependent upon complement fixation by the complexes. The amount of platelet-aggregating material detected in vitro correlated closely with in vivo depletion of intraplatelet amines, judged by serotonin concentrations; which suggests that this material may play a major role in platelet activation within the circulation.