Specificities of leucocyte alloantibodies in transfusion-related acute lung injury and results of leucocyte antibody screening of blood donors

Background Antibody-mediated transfusion-related acute lung injury (TRALI) is an important cause of transfusion-associated morbidity and death. Preventive strategies are currently a matter of debate. Methods Specificities of leucocyte antibodies implicated in previous severe TRALI reactions were determined using standard techniques. Based on these results, a leucocyte antibody screening strategy for the testing of parous female donors was introduced. Results Of 36 TRALI cases, 17, 12, four and three were due to human leucocyte antigen (HLA) class II, human neutrophil alloantigen (HNA), HLA class I, and mixtures of HLA class I and II antibodies, respectively. HNA-3a antibodies accounted for 10 of 12 HNA antibody-mediated reactions and 6 of 10 fatalities including one after transfusion of red blood cells. Investigation 5332 parous female donors showed leucocyte antibodies in 473 samples, resulting in an alloimmunization rate of 8.9%. Sixty-one per cent of these donors presented HLA class I, 19% class II, 12% HLA class I and II antibodies and 5% HNA antibodies. Additional HLA class I antibodies were found in 39% of HLA class II and in 17% of HNA antibodies containing sera. Our restrictive plasma strategy did not result in a shortage of plasma or platelets. No antibody-mediated TRALI case was observed since introduction of the policy of plasma from male, nulliparous or tested multiparous donors. Conclusion Compared to HLA class I antibodies, those directed against HLA class II and HNA-3a were of greater clinical relevance. Isolated HLA class I antibody screening was found to be insufficient for leucocyte antibody screening.