Experience with protein A-immunoadsorption in treatment-resistant adult immune thrombocytopenic purpura

Abstract

Extracorporeal immunoadsorption of plasma to remove IgG and circulating immune complexes (CIC) was evaluated as a therapy for adults with treatment-resistant immune thrombocytopenic purpura (ITP). Seventy-two patients with initial platelet counts <50,000/μL who had failed at least two other therapies were studied. They received an average of six treatments of 0.25 to 2.0 L plasma per procedure over a 2- to 3-week period using columns of staphylococcal protein A-silica (PROSORBA® immunoadsorption treatment columns; IMRÉ Corp, Seattle, WA). The treatments caused an acute increase in the platelet count to >100,000/μL in 18 patients and to 50,000 to 100,000/μL in 15 patients. The median time to response was 2 weeks. Responses were transient (<1 month duration) in seven of those patients (10%), but no additional relapses were reported over a follow-up period of up to 26 months (mean of 8 months). Clinical responses were associated with significant decreases in specific serum platelet autoantibodies (including anti-glycoprotein IIb/IIIa), platelet-associated Ig, and CIC. Thirty percent of treatments were associated with transient mild to moderate side effects usually presenting as a hypersensitivity-type reaction. Continued administration of failed therapies for ITP, which always included low-dose corticosteroids (<30 mg/d), had no demonstrable influence on the effectiveness of immunoadsorption treatment but did depress the incidence and severity of side effects. The degree of effectiveness of protein A immunoadsorption therapy in patients with treatment-resistant ITP is promising and further controlled studies in this patient population are warranted. © 1992 by The American Society of Hematology.