Reticuloendothelial system Fc-receptor function in patients with immune thrombocytopenia after treatment with high dose intravenous immunoglobulin

Reticuloendothelial system Fc-receptor (FcR) function was measured in 4 healthy controls and 9 patients with immune thrombocytopenia before and after therapy with high dose i.v. gammaglobulin (HDIg). Idiopathic thrombocytopenic purpura (ITP) was diagnosed in 5 patients. 2 patients with hemophilia A, 1 with acute tuberculosis and 1 with psoriasis vulgaris had thrombocytopenia that clinically resembled ITP. 4 out of 9 patients received prednisone prior to or during the study. FcR blockade was observed only in patients with ITP not receiving prednisone. In all other patients, HDIg did not induce a measurable FcR blockade. However, all except 1 patient (with acute tuberculosis) showed a marked rise in platelet counts for 2 to 12 wk. This is consistent with therapeutic efficacy of HDIg in various clinical settings of immune thrombocytopenia. All platelets were fully hemostatic and clinically no difference could be observed. This indicates that the effect of HDIg cannot be due to FcR blockade alone.