Screening plateletpheresis donors for HLA antibodies on two high-throughput platforms and correlation with recipient outcome.

BACKGROUND: To determine the prevalence and impact of transfusing plasma containing white blood cell antibodies, we compared two high-throughput HLA antibody screening assays and prospectively examined the medical records of all platelet (PLT) recipients to detect subtle manifestations of transfusion-related acute lung injury and other transfusion reactions. STUDY DESIGN AND METHODS: Serum samples from 136 plateletpheresis donors were tested for HLA Class I and II antibodies using microbead (LABScreen PRA, One Lambda) and microchip (Dynachip, Invitrogen) assays. Electronic medical records of all recipients were reviewed for vital signs and nursing documentation before and after transfusion.
RESULTS: In the microchip assay with a cutoff value of 0.25, 2.9% of samples were positive for Class I and 8.9% for Class II antibodies; with a cutoff value of 0.1, the results were 14.9 and 21.6%, respectively. In the microbead assay (normalized background ratio, 1.5), 15% were positive for Class I and 21% for Class II antibodies. The prevalence of HLA antibodies was 17% in donors without pregnancy or transfusion history and 47% in donors with such history. The PLTs were transfused in 265 episodes to 67 patients. There were no reported reactions; however, symptoms or vital sign changes were noted in seven transfusion episodes. The incidence of reactions was 2.7% (2/75) for antibody-positive units and 2.6% (5/190) for antibody-negative units.
CONCLUSIONS: Microbead and microchip assays yielded similar results. The prevalence of HLA antibodies was greater in donors with a history of pregnancy or transfusion, but no increase in the incidence of transfusion reactions was noted in recipients of components from donors with HLA antibodies.