Immune Thrombocytopenia: A Platelet-Centric Model of Autoimmune Dysregulation.

Immune thrombocytopenia is an acquired autoimmune disorder characterized by thrombocytopenia resulting from increased platelet destruction and impaired platelet production. Although traditionally considered an antibody-mediated disease in which autoreactive plasma cells generate antibodies against platelet glycoproteins, contemporary evidence demonstrates a more complex pathogenesis also involving cytotoxic T lymphocytes, complement activation, platelet desialylation, abnormal megakaryopoiesis, and defective immune tolerance. Importantly, platelets are increasingly recognized not simply as passive targets of the autoimmunity but as immunologically active cells capable of modulating the autoimmune response directed against themselves.