PLATELET-AGGREGATING IMMUNE-COMPLEXES AND INTRAPLATELET SEROTONIN IN IDIOPATHIC GLOMERULONEPHRITIS AND SYSTEMIC LUPUS

Abstract

Immune complex-like material was studied using the platelet-aggregation test (PAT) in 114 patients with idiopathic glomerulonephritis and 55 patients with SLE [systemic lupus erythematosus] nephritis. The obtained results compared with [human Burkitts lymphoma] Raji cell and C1q[a fragment of complement component 1]-binding assays. The platelet-aggregating material was not thrombin and eluted from Sepharose CL/6B columns with a MW of greater than 500,000 daltons, Sera from 17 of 55 patients with SLE nephritis were positive in all 3 assays, 50/55 in at least 1 assay. No circulating material was detected by the Raji cell assay in idiopathic glomerulonephritis patients; the C1q-binding adn PAT assays detected material in patients with acute post-infectious nephritis and mesangiocapilllary glomerulonephritis. Patients with membranous nephropathy and Henoch-Schonlein purpura were positive in the PAT, although generally negative in the other assays of immune complexes. The amount of platelet-aggregating material (PAM) found in the sera of patients with idiopathic glomerulonephritis and SLE nephritis correlated closely with the depletion of intraplatelet serotonin, suggesting that this material is a major mechanism of in vivo platelet activation in these patients.