Idiopathic thrombocytopenia purpura (ITP) is a primary immune thrombocytopenia that is typically manifested in adults by acute bleeding, severe thrombocytopenia, and normal to increased megakaryocytes in the bone marrow. Labeling studies suggest that most patients with ITP have an IgG antibody directed against the platelet membrane resulting in sequestration in the spleen. Splenectomy and/or corticosteroids remain the mainstay of therapy, with permanent remissions induced in 75% of patients. Despite the use of cyclophosphamide, azathioprine, vincristine, high-dose gamma globulin, and other forms of therapy, less than 50% of refractory patients achieve long-term satisfactory platelet counts. In view of these facts, ten consecutive patients with immune thrombocytopenia, unrelated to human immunodeficiency virus (HIV), received plasma perfusion over a staphylococcal protein A column (PROSORBA column) to evaluate efficacy and toxicity. All patients had an initial platelet count less than 50,000 and had failed corticosteroids. Five patients had also failed splenectomy. Two patients were not splenectomized due to pediatric age, two due to severe coexisting medical conditions, and one due to refusal of operation. Multiple other forms of therapy had also failed in this cohort of patients. Patients received two to ten treatments with the protein A column. All patients are evaluable for response and toxicities. Of the ten patients, results were as follows: complete response in one (platelet count greater than 150,000); partial response in four (platelet count greater than 50,000 and less than 150,000); and no response in five. Duration of responses ranged from 1 to 6 or more months.(ABSTRACT TRUNCATED AT 250 WORDS)