TRANSFUSIONS TO GROUP-O SUBJECTS OF 2 UNITS OF RED-CELLS ENZYMATICALLY CONVERTED FROM GROUP-B TO GROUP-O

Background: It has previously been shown that full-unit (200 mL) transfusions of red cells (RBCs) enzymatically converted from group B to group O by treatment with alpha-galactosidase (ECO RBCs) are both safe and efficacious for normal group O or A subjects. Study Design and Methods: The present study describes the results of a comprehensive clinical and serologic assessment of 2-unit (400 mL) ECO RBC transfusions to each of four normal group O subjects (after each had donated 1 unit of whole blood). Results: Clinical (hematologic tests, chemistry analysis, urinalysis) and serologic analyses revealed no evidence of immediate or delayed transfusion reaction, despite a threefold to fivefold elevation in pre-existing anti-B antiglobulin titer. Cr-51-labeled ECO RBCs were administered to one of the four subjects to allow direct measurement of ECO RBC survival in the circulation, which indicated that it was normal (24-hour survival, 95%; t1/2, 29.5 days). The observed increases in hemoglobin (by 1.3 +/- 0.4 g/dL [13 +/- 4 g/L]) and hematocrit (by 3.2 +/- 0.8% [0.032 +/- 0.008]) in transfused subjects provide further evidence of the efficacy of these cells in vivo. Conclusion: These results extend those observed in our earlier 1 -unit transfusion studies and suggest that ECO RBCs pose little risk and will be useful in transfusion medicine.