RED-BLOOD-CELL ALLOIMMUNIZATION IN SICKLE-CELL DISEASE - THE INFLUENCE OF RACIAL AND ANTIGENIC PATTERN DIFFERENCES BETWEEN DONORS AND RECIPIENTS IN BRAZIL

Red blood cell (RBC) transfusions are widely used in the management of patients with sickle cell disease (SCD). However, repeated RBC transf usions are often complicated by RBC alloimmunization. To investigate w hether the frequency of RBC alloimmunization could be accounted for by racial and RBC phenotype differences between donors and recipients in Brazil, in this study we compared the RBC phenotype of 100 SCD patien ts with that observed in 120 randomly selected blood donors. A compari son of the RBC phenotype between the two groups revealed a statistical ly significant increase in the frequency of the C antigen in the donor population (P < 0.01), but no significant difference was observed for the A, B, D, c, E, e, K, k, Fy(a), M, N, S, s, and Jk(a) antigens. Us ing standard techniques (indirect antiglobulin test, enzyme treatment, and low-ionic-strength solution) we observed an RBC alloimmunization rate of 12.9% (11/85) in the SCD patients. Fifteen alloantibodies were detected in 11 patients, and most (80%) involved antigens in the Rhes us and Kelt systems. This observed RBC alloimmunization rate in SCD pa tients in Brazil is lower than that reported by studies from North Ame rica, suggesting that the requirement for extended antigen-matched RBC transfusion for SCD patients in the setting of a RBC phenotype concor dant donor-recipient population may not be cost-effective in some coun tries. (C) 1996 Wiley-Liss, Inc.