A Two-Event In Vivo Model of Transfusion-Related Acute Lung Injury.

TRALI is the most common cause of transfusion-related death in the US, and the pathogenesis is related to the infusion of donor anti-leukocyte antibodies or biologic response modifiers (BRMs) including lipids that accumulate during storage of cellular components. We hypothesize that TRALI is the result of two distinct events: the first related to the clinical condition of the patient resulting in pulmonary endothelial activation and sequestration of PMNs and the second is the infusion of antibodies or BRMs along with the transfused product. Methods: PRBCs were obtained from 5 donors and 50% were pre-storage leukoreduced by filtration and the other 50% left as a control, and both stored per AABB criteria. Plasma samples were obtained serially from these units and was heat-treated (56°C for 30 min) to destroy fibrinogen and complement prior to administration. Antibodies to antigens present on leukocytes from Sprague Dawley rats including MHC class I: OX18 & OX27, MHC class II: OX3 & OX6 and anti-granulocyte (PMN) antibodies were obtained commercially. Male rats were given saline (NS) or 2 mg/kg IP of endotoxin (LPS S.enteritidies, non-lethal), incubated for 2 hrs, anesthetized with pentobarbital, the femoral vessels were cannulated, and 10% of the blood volume was withdrawn over 15 min. Plasma from day 1 (10% final) and day 42 (5–10%) PRBCs and 10% LR-PRBCs, and 50 or 100 μg of antibodies (500μl of sera, anti-PMN) were infused over 30 min, followed by IV Evan’s Blue dye (30 mg/kg; 1ml) that binds to albumin. At 6 hours, plasma and bronchoalveolar lavage (BAL) fluid were obtained to determine the % of Evan’s Blue leak into the BAL at 620 nm. Mortality was < 5%. Acute lung injury (ALI) was precipitated in LPS-treated animals by day 42 PRBC plasma (5% & 10%), 10% day 42 LR-PRBC plasma and antibodies to MHC class I antigens (Table). With NS as the first event, rats did not evidence ALI for all groups, including MHC class I antibodies. Moreover, in LPS pre-treated rats, second events consisting of NS, day 0 PRBC, day 0 LR-PRBC plasma, antibodies to MHC class II antigens (OX3 & OX6) and anti-PMN antibodies did not elicit ALI (Table). We conclude that 1) this in vivo model approximates the mortality of the clinical condition, 2) it demonstrates that the pathogenesis requires two events to elicit antibody-induced or BRM-mediated TRALI, and 3) ALI as the result of LPS/MHC class I antibodies evidences a dose-response. ALI as a a Function of Evans Blue Dye Leak 1st Event ⇒ Normal Saline NS LPS 2nd Event ⇓ †=p<.05 vs. 1st event or 2nd event Normal Saline 0.08±0.03 0.24±0.11 MHC Class I OX18 50μg 0.06±0.06 0.18±0.03 MHC Class I OX18 100μg 0.17 1.91±0.7] MHC Class I OX27 50μg 0.19±0.04 1.26±0.1† MHC Class II OX3 50μg 0.07 0.4 MHC Class II OX6 50μg 0.07±0.07 0.2±0.07 Anti-Granulocyte serum 500μl 0.25±0.14 0.22±0.17 Anti-Granulocyte 100μg 0.174 0.09±.02 PRBCs day 1 [10%] 0.10±0.08 0.25±0.09 PRBCs day 42 [5%] 0.13±0.07 2.48±0.46† PRBCs day 42 [10%] 0.16±0.10 1.16±0.34† LR-PRBCs day 1 [10%] 0.16±0.09 0.19±0.05 LR-PRBCs day 42 [10%] 0.20±0.12 2.69±0.58†