Splenectomy was employed as therapy for patients with idiopathic thrombocytopenic purpura long before the immunologic nature of the disease was firmly established. However, soon after Harrington observed that infusion of plasma from patients with the disorder produced thrombocytopenia in normal persons, it was noted that splenectomy or administration of corticosteroids could give partial protection against this fall in platelet count.1,2 The fate of sensitized platelets has also been determined by isotopic labeling combined with surface scanning. After infusion of labeled platelets into patients with idiopathic thrombocytopenic purpura, there is accumulation of radioisotope in both liver and spleen. However, the predominant . . .