Elevated platelet-bound IgG associated with an episode of thrombotic thrombocytopenic purpura

The level of platelet-associated IgG (PAIgG) were measured during the successful treatment of a patient with thrombotic thrombocytopenic purpura. Prior to therapy. PAIgG was found to be markedly elevated to 195 fg/cell (normal range 0--3.5 fg/cell). The institution of combined therapy with intensive plasma exchange transfusions, high-dose steroids, and antiplatelet drugs resulted in a complete recovery and a decline in PAIgG to the normal range. The possible role of platelet antibody in the pathogenesis of this disorder is discussed.