Effects Of Plasma From Adult Patients With Chronic ITP On In Vitro Megakaryocytopoiesis And Platelet Production And Related Mechanism

Idiopathic thrombocytopenic purpura (ITP) is a common hematologic disorder characterized by a low platelet count, detectable autoantibodies binding to platelet glycoproteins and normal or increased number of megakaryocytes in bone marrow.The pathogenetic mechanism of ITP is not completely clear yet. It has been long believed that thrombocytopenia is mediated by autoantibodies. Platelets from 50%-60% of ITP patients are coated with IgG antibodies that recognize one or more platelet surface glycoproteins. The antibody-coated platelets are destructed either by phagocytic cells or by autoantibody-induced activation of complement. However, autologous platelet survival studies in the 1980s showed that in approximately two thirds of ITP patients, platelet turnover is either reduced or normal, not increased as would be expected if platelet destruction were the only mechanism causing thrombocytopenia. Since megakaryocytes also express GP IIb/IIIa and GP I b/IX on there surfaces during maturation and most ITP autoantibodies react with one or both of the these glycoprotein complexes, it follows that autoantibodies binding to...