Non antibody‐mediated TRALI – current understanding

Abstract

Transfusion‐related acute lung injury (TRALI) is suggested to follow a ‘two‐hit’ mechanism. The ‘first hit’ is the underlying condition of the patient (e.g. sepsis) resulting in priming of neutrophils and/or endothelium. The ‘second hit’ is any transfusion resulting in activation of the primed neutrophils and/or endothelium. The transfusion factors can be divided into antibody‐mediated and non‐antibody‐mediated TRALI. Antibody‐mediated TRALI is caused by passive infusion of donor antibodies reacting with the cognate antigen of the recipient. Non‐antibody‐mediated TRALI is thought to be caused by the transfusion of stored cellular blood products. Although the mechanisms involved in antibody‐mediated TRALI have been well outlined and confirmed in preclinical and clinical studies, this is not the case for non‐antibody‐mediated TRALI. Preclinical studies show a strong association between storage time of cellular blood products and the onset of lung injury. However, recent clinical studies show contradictory results. In this review, the latest insights on the pathogenesis of non‐antibody‐mediated TRALI will be discussed as well as the areas future research should be focused on.