Treatment of patients with HIV thrombocytopenia and hemolytic uremic syndrome with protein A (Prosorba column) immunoadsorption.

Both antibodies and circulating immune complexes (CIC), which bind to platelets and induce the destruction and clearance of platelets by the reticuloendothelial system, are found in patients with human immunodeficiency virus (HIV) and immune thrombocytopenic purpura (ITP). IgG and CIC were removed from patients' plasma by extracorporeal immunoadsorption using protein A-silica columns (PROSORBA columns). Of the 36 HIV-positive ITP patients treated, 29 received more than one treatment and were evaluated for response. Sixteen patients showed more than a 50% increase in their platelet counts. Platelet-associated IgG (PAIgG) and/or platelet-directed IgG and CIC were elevated in all patients. After four to eight treatments, 16 of 29 patients showed a 170% to 430% increase in platelet counts. A decrease in CIC and PAIgG was noted in responding patients. The median duration of response to date was 8 to 12 months. This treatment was associated with immune modulation and the development of an anti-F (ab')2 antibody response. The antibody functions by complexing with both platelet-binding IgG and CIC, neutralizing their binding capacity for platelets and enhancing their clearance from the circulation. Nine patients with mitomycin-C-induced hemolytic uremic syndrome (HUS) were also treated with PROSORBA columns. Pretreatment platelet counts were markedly reduced while a definite increase in platelet counts was observed upon completion of therapy. There was a decrease of hemolysis and stabilization of renal function in three patients. PROSORBA column treatment has demonstrated marked activity against both HIV-ITP and HUS, and has successfully freed patients from the bleeding diathesis associated with these syndromes.