Fc receptor blockade in patients with refractory chronic immune thrombocytopenic purpura with anti-D IgG

Background. This is an evaluation of the treatment of 63 patients with chronic immune thrombocytopenic purpura (54 splenectomized and nine nonsplenectomized) with weekly doses of anti-D (IgG)-coated red blood cells (RBCs). Methods. All patients were given one 5-15 mug/kg/dose of intravenous (i.v.) anti-D (IgG)coated RBCs per week (average of 300 mug/dose/week) for a median 3-month period (3-6 months). Treatment modality was evaluated on a weekly basis by platelet counts, measuring of hemoglobin levels, and performance of Coombs tests. Results. All patients presented a clinical response. Fifty-two patients (82.5%) increased their platelet count (PC) and 45 (69.8%) increased their PC >50 X 10(9)/L. In 34 cases, response was sustained. Six of nine nonsplenectomized patients (67%) increased PC, thus avoiding splenectomy; four patients attained a stable complete response (CR). Similar platelet responses were observed in homozygous and heterozygous Rh (D)-positive patients (Rh/Hr phenotypes). Currently, after >10 years, 43 patients present a now permanent complete response with platelet count 50 X 10(9)/L. Ten patients subsequently decreased their platelet count, although they were able to attain CR after receiving six doses of anti-D (IgG)-coated RBCs. Conclusions. Based on our study of Fc receptor blockade treatment with anti-D (IgG)coated RBCs with the most difficult cases of ITP, which resulted in a 69.8% successful response rate, we concluded that weekly prescription of anti-D (IgG)-coated RBCs is an effective approach to treating chronic refractory ITP. (C) 2002 IMSS. Published by Elsevier Science Inc.