Transfusion-related acute lung injury (TRALI) is the leading cause of transfusion death. We hypothesize that TRALI requires 2 events: (1) the clinical condition of the patient and (2) the infusion of antibodies against MHC class I antigens or the plasma from stored blood. A 2-event rat model was developed with saline (NS) or endotoxin (LPS) as the first event and the infusion of plasma from packed red blood cells (PRBCs) or antibodies (OX18 and OX27) against MHC class I antigens as the second event. ALI was determined by Evans blue dye leak from the plasma to the bronchoalveolar lavage fluid (BALF), protein and CINC-1 concentrations in the BALF, and the lung histology. NS-treated rats did not evidence ALI with any second events, and LPS did not cause ALI. LPS-treated animals demonstrated ALI in response to plasma from stored PRBCs, both prestorage leukoreduced and unmodified, and to OX18 and OX27, all in a concentration-dependent fashion. ALI was neutrophil (PMN) dependent, and OX18/OX27 localized to the PMN surface in vivo and primed the oxidase of rat PMNs. We conclude that TRALI is the result of 2 events with the second events consisting of the plasma from stored blood and antibodies that prime PMNs. IntroductionTransfusion-related acute lung injury (TRALI) is the leading cause of transfusion mortality in the United States. 1,2 TRALI is the acute onset of noncardiogenic pulmonary edema as documented by chest radiograph and profound hypoxemia, in accordance with the definition of acute lung injury (ALI), that occurs within 6 hours of transfusion. 3,4 TRALI may occur with or without conditions that predispose the patient to ALI, and may be the worsening of pulmonary function in patients with preexisting ALI. 3,4 All blood products have been implicated in TRALI, but components that contain large amounts of plasma are mainly responsible. 5,6 The current incidence of TRALI has been estimated as 1/7900 to 1/1330 in the United Kingdom and the United States with lesser incidences in Europe. [5][6][7][8] Current mortality rates vary from 5% to 35% with the lesser mortality rates predominating. [5][6][7][8] The pathophysiology of TRALI has not been elucidated despite numerous studies. [9][10][11][12][13][14] The first mechanism proposed was the infusion of donor antibodies directed against the HLA class I or granulocyte-specific antigens on the recipient's leukocytes with animal models composed of an in vivo murine model and an isolated, perfused rabbit lung that provided physiologic relevance. [9][10][11][12]14 In addition, the neutrophil (PMN) was proposed to be the effector cell, identical to other forms of ALI and the acute respiratory distress syndrome (ARDS). [9][10][11][12]14 However, look-back studies of donors with specific antibodies directed against HLA or granulocyte antigens demonstrated that the infusion of donor antibodies into a recipient that expressed the cognate antigen resulted in TRALI in a minority of these patients, implying that the clinical condition of the recipient may be important for the d...

Transfusion of autologous blood is associated with fewer complications, although all untoward events of transfusion may not be negated with this strategy. We report a case of acute pulmonary insufficiency and hypotension following transfusion of autologous packed red blood cells (PRBCs) in a patient, who was undergoing major surgery. Anti-HLA class-I and class-II and anti-granulocyte antibodies were measured in the unit and in the recipient. Neutrophil (PMN)-priming activity was measured as the augmentation of the formyl-Met-Leu-Phe-activated respiratory burst. No immunoglobulins were identified; however, significant lipid-priming activity was present in the implicated, autologous PRBC unit that primed PMNs from both healthy people and the recipient. In addition, lipids, identical to those that accumulate during PRBC storage, caused significant hypotension when infused into rats at similar concentrations found in stored PRBCs. We conclude that the observed transfusion-related acute lung injury reaction with significant hypotension may be the result of two independent events: the first is related to inherent host factors, in this case major surgery, and the second is the infusion of lipids that accumulate during the routine storage of PRBCs.