Definition Of Transfusion-related Acute Lung Injury Research Articles

Redefining transfusion-related acute lung injury: don't throw the baby out with the bathwater.

Recently two articles have been published in TRANSFUSION in which the authors propose to change the current definition on transfusion-related acute lung injury (TRALI). It was proposed to view TRALI from the perspective of detectability versus nondetectability of leukoreactive alloantibodies (Transfusion 2015;55:1128-34). The authors argue that only cases in which leukoreactive alloantibodies can be detected should be defined as "true" TRALI in analogy with the understanding of the pathophysiology of heparin-induced thrombocytopenia. In the other article (Transfusion 2015;55:947-52), the authors propose to redefine possible TRALI to transfused acute respiratory distress syndrome (ARDS) as their study in intensive care unit patients did not show a relation between the number of transfusions and possible TRALI.We discuss these two propositions in light of the current evidence on pathophysiology of TRALI and possible TRALI. We argue that it is too early to redefine TRALI, as 1) factors, such as storage time of platelets, which induce TRALI in preclinical studies, have not yet been properly investigated in humans. Further research is needed on these agents before it is concluded that antibody-mediated TRALI is the only "true" TRALI. 2) In light of the current knowledge, it makes perfect sense that multiple transfusion is not related to possible TRALI: ARDS risk factors in these patients result in a very sensitive equilibrium in which even only one transfusion induces TRALI. Excluding possible TRALI from the TRALI definition would result in further underrecognition of TRALI induced by alloantibodies and interferes with exclusion of donors related to TRALI cases and thus TRALI prevention.

Transfusion-related acute lung injury

Transfusion-related acute lung injury (TRALI) is a life-threatening adverse event of transfusion, which has an increasing incidence in the United States and is the leading cause of transfusion-related death. TRALI and acute lung injury (ALI) share a common clinical definition except that TRALI is temporally- and mechanistically-related to transfusion of blood or blood components. A number of different models have been proposed to explain the pathogenesis. The first is an antibody-mediated event whereby transfusion of anti-HLA, class I or class II, or anti-granulocyte antibodies into patients whose leukocytes express the cognate antigens. The antibody:antigen interaction causes complement-mediated pulmonary sequestration and activation of neutrophils (PMNs) resulting in TRALI. The second is a two-event model: the first event is the clinical condition of the patient resulting in pulmonary endothelial activation and PMN sequestration, and the second event is the transfusion of a biologic response modifier (including anti-granulocyte antibodies, lipids, and CD40 ligand) that activates these adherent PMNs resulting in endothelial damage, capillary leak, and TRALI. These hypotheses are discussed with respect to animal models and human studies that provide the experimental and clinical relevance. The definition of TRALI, patient predisposition, treatment, prevention and reporting guidelines are also examined.