BACKGROUND: Alloimmunization to red blood cell (RBC) blood group antigens is a major complication for patients with sickle cell disease (SCD), which limits the usefulness of RBC transfusion. Here, we report our experiences with extended RBC antigen matching for SCD patients.
STUDY DESIGN AND METHODS: Records for 99 SCD patients transfused only with the extended matching protocol between 1993 and 2006 were reviewed. Patients and donors were phenotyped for 20 blood group antigens and RBC units that were negative for antigens not expressed by the recipient were provided. When necessary, mismatches were allowed at Lea, Leb, Fyb, and MNSs to meet requirements for antigens regarded as the most clinically significant. Matched RBC units (6946) were provided to 99 patients (mean, 70 units/patient; range, 1-519 units/patient). Eliminating mismatches, 90% of the transfusions matched all other negative antigens.
RESULTS: Seven alloantibodies were detected in seven patients resulting in 7% alloimmunized at a rate of 0.1 antibodies per 100 units transfused. Three recipients who developed antibodies were D mosaic and would have been mistyped with serologic techniques. Alloimmunization was decreased compared to ABO and/or D matching at our institution and others. Twelve autoantibodies and no severe hemolytic transfusion reactions were reported.
CONCLUSION: Exact matching for ABO, Rhesus, Kell, Kidd, and Fya and extending this match whenever possible is an effective strategy to reduce alloimmunization to RBC antigens. Consideration should be given to exploring this conclusion further with a controlled, multi-institutional trial to determine efficacy, cost-benefit analysis, and reproducibility of this approach.