Serum Factors Releasing Serotonin from Normal Platelets: Relation to the Manifestations of Systemic Lupus Erythematosus

Abstract

In 13 patients with systemic lupus erythematosus, globulin fractions of sera from serial bleedings were assayed for the induction of serotonin release from normal platelets. Releasing activity appeared at some time in the sera of 7 patients, 5 of whom had episodes of thrombocytopenia. Conversely, only 1 patient manifested thrombocytopenia without the occurrence of serotonin releasing activity at any time. In 3 patients with episodes of thrombocytopenia, increases in serotonin releasing activity temporally coincided with drops in platelet count. Levels of circulating platelet serotonin releasing factor(s) vary in the course of systemic lupus erythematosus and these variations may be inversely related to the platelet count in particular patients.