Pathogenesis of non-antibody mediated transfusion-related acute lung injury from bench to bedside

Transfusion-related acute lung injury (TRALI) is a major cause of transfusion-related mortality. Causative factors are divided in antibody mediated TRALI and non-antibody mediated TRALI. Antibody mediated TRALI is caused by passive transfusion of cognate antibodies and non-antibody mediated TRALI is caused by transfusion of aged cellular blood products. This review focuses on mechanisms in non-antibody mediated TRALI which includes soluble mediators accumulating during storage of red blood cells (RBCs) and platelets (PLTs), as well as changes in morphology and function of aged PLTs and RBCs. These mediators cause TRALI in two-hit animal models and have been implicated in TRALI onset in clinical studies. Pre-clinical studies show a clear relation between TRALI and increased storage time of cellular blood products. Observational clinical studies however report conflicting data. Knowledge of pathophysiological mechanisms of TRALI is necessary to improve storage conditions of blood products, develop prevention strategies and develop a therapy for TRALI.