Non-antibody mediated transfusion-related acute lung injury an enigma

In 20% to 28% of transfusion-related acute lung injury (TRALI) cases, no leucocyte antibodies have been detected and such cases are described as non-antibody mediated TRALI. In the other 72% to 80% of TRALI cases, leucocyte antibodies are hypothesized to be the “second hit” that precipitates acute lung injury (ALI) in a sick patient. There is a substantial body of evidence demonstrating an association between TRALI and antibodies to human neutrophil antigens (HNA), human leukocyte antigens (HLA) class I and II. Therefore, one of the most widely used TRALI mitigation strategies has been to reduce/avoid use of blood components that contain or are more likely to contain these antibodies. Despite the success of these risk reduction strategies, hemovigilance data show that TRALI remains a serious and sometimes fatal complication of transfusion. This is possibly because the current TRALI risk-reduction strategies all focus on antibody mediated TRALI but do not address non-antibody mediated TRALI. This review discusses the available evidence on non-antibody mediated TRALI.