Transfusion to blood group A and O patients of group B RBCs that have beenenzymatically converted to group O

BACKGROUND: The transfusion of ABO-incompatible RBCs is the leading cause o f fatal transfusion reactions. Group O RBCs, lacking terminal immunodominan t A and B sugars to which humans are immunized, are safe for transfusion to persons of any ABO blood group. With the use of a recombinant alpha -galac tosidase to remove terminal galactose from group B RBCs, the safety and eff icacy of enzyme-converted group-B-to-group-O (ECO) RBC components were stud ied in transfusion-dependent patients. STUDY DESIGN AND METHODS: Twenty-four patients (blood groups A and O) were randomly assigned to receive transfusion(s) of either ECO or control group O RBCs. If a second transfusion was given, the other blood component was ad ministered. RESULTS: Twenty-one patients were given ECO RBCs; 18 also underwent control transfusions. One patient received only a small aliquot for RBC survival s tudies, instead of a full-unit transfusion, because his serum was incompati ble with ECO RBCs. No adverse events occurred. Both ECO and control transfu sions resulted in appropriate Hb increments and comparable Cr-51-labeled RB C survival studies. One patient developed a transient, weak-positive DAT, w ithout hemolysis. Two weeks after transfusion, 5 of 19 evaluable ECO RBC re cipients had increases in anti-B titers. CONCLUSION: ECO RBCs were comparable to group O cells for safety and effica cy in this study. The clinical significance of the increase in anti-B and o f occasional serologic incompatibilities with ECO RBCs is unclear. If strat egies can be developed to remove A epitopes, enzymatic conversion could be used to create a universal (group O) donor blood supply.