Stimulation of Nonimmunized Lymphocytes by Platelet-Antibody Complexes in Idiopathic Thrombocytopenic Purpura

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Abstract
Platelets preincubated in serum from patients with immunologic thrombocytopenia stimulate autologous lymphocytes in culture. Stimulation of new deoxyribonucleic acid synthesis by cultured lymphocytes was measured by the uptake of tritiated thymidine. The lymphocyte-stimulating activity in serum was heat stable, could be adsorbed by autologous and homologous platelets, was inhibited by anti-human immunoglobulin G, and chromatographed as immunoglobulin G on diethylaminoethyl cellulose. The degree of stimulation was proportional to the number of platelets in each culture and was maximal on the sixth day of culture. With this technic, presumptive antibody was detected in 25 of 26 patients with idiopathic thrombocytopenic purpura and eight of nine with other types of immune thrombocytopenia. The lymphocyte-stimulating activity in idiopathic thrombocytopenic purpura persisted after clinical remission induced by steroids, splenectomy or cyclophosphamide therapy. Normal lymphocytes thus appear to be nonspecifically stimulated by antigen-antibody complexes created by incubation of platelets in immune serum. (N Engl J Med 289:714–718, 1973)