Alpha interferon therapy in the treatment of idiopathic thrombocytopenic purpura

Treatment of patients with idiopathic thrombocytopenic purpura (ITP) varies according to the severity of the condition, the patient's age and the phase of the disease. The mainstay of treatment is corticosteroid therapy, with splenectomy for non-responding patients. For the 5%–10% of patients with refractory disease and bleeding problems, intravenous immunoglobulins are often used. Danazol achieves a response in about 30%–40% of refractory patients. At our centre, we have now treated 13 patients with interferon alfa-2b, all of whom had severe steroid-unresponsive ITP of various durations. All patients received 12 injections of 3 million units (MU) interferon subcutaneously three times a week. The platelet count rose significantly in 10 patients after interferon therapy and in one patient during therapy. Three patients had a complete response and eight a partial response. One complete responder relapsed at 5 months but again responded to retreatment with interferon. Responses were similar in splenectomized and non-splenectomized patients, and platelet-associated immunoglobulin levels remained essentially unchanged. Based on a compilation of data from this and other studies, the positive response rate (platelets at least 30–200 × 10⁹/L for at least 6 weeks) is 69% ($\text{22}\text{32}$ patients). The future role and dosage of interferon in ITP remains to be determined and particularly in direct comparison with intravenous IgG therapy.