Relative efficacy of steroid therapy in immune thrombocytopenia mediated by anti-platelet GPIIbIIIa versus GPIbα antibodies

Immune thrombocytopenia (ITP) is characterized by platelet clearance mediated primarily by autoantibodies against the platelet GPIIbIIIa and/or GPIba. Steroid therapy is a first-line treatment for ITP. However, some patients are refractory to this therapy and currently no method can predict which patients will respond. To evaluate whether steroids are equally efficacious in treating patients with ITP caused by anti-GPIIbIIIa versus anti-GPIba antibodies, we performed a retrospective study on 176 newly diagnosed patients with acute ITP who had severe bleeding symptoms and were admitted as resident patients to the hospital. The patients were treated first with intravenous administration of high-dose dexamethasone (DXM), followed by oral administration of prednisone. Response to therapy was observed in a majority of patients with antibodies specific for GPIIbIIIa (31/43) or without detectable antibodies against either GPIIbIIIa or GPIba (36/45). In contrast, the steroid response was significantly lower in patients with anti-GPIba antibodies (9/34) or with antibodies against both GPIba and GPIIbIIIa (16/54). The preliminary findings of this study suggest that in future prospective clinical trials including corticosteroids, the anti-GPIba, and -GPIIbIIIa status should be assessed in order to test its potential relevance in deciding future treatments. (C) Wiley Periodicals, Inc.