Comparison of antibody titers in donor specimens and associated AS-1 leukoreduced donor units

Donor units with unexpected antibodies to red blood cell (RBC) antigens have transfusion restrictions and are often discarded by collection facilities. This study examined the antibody titer reduction in AS-1 leukoreduced RBC (LR-RBC) units and potential acceptability of these units for unrestricted transfusions.

Donor specimens and AS-1 LR-RBC segment samples from donors with positive antibody screens and group O donors were analyzed. Antibody identifications were performed, and titer results from the matched serum samples and segment supernatants were compared.

During the 5-month study, 39 donor samples with positive antibody screens, five random group O donor samples, and the associated LR-RBC unit segments were assessed. The median donor sample and segment supernatant titers were 4 and 1, respectively. Alloantibodies were undetectable in 28% of the donor segment supernatants. The median anti-A and anti-B titers in the group O donor samples were 128 and were reduced to 32 in the donor segment supernatants. All ABO and other antibodies were diluted by the AS-1 to a titer of not more than 32.

Antibody titers in AS-1 LR-RBC units were significantly decreased compared to donor specimens and were lower than anti-A and -B titers in group O AS-1 LR-RBC units, which are frequently transfused to non-group O recipients. If a "clinically significant" titer for donor alloantibodies was established, blood centers could determine eligibility of units for unrestricted transfusions. This would decrease unnecessary RBC wastage and increase units available for transfusion.