HLA CLASS II ANTIBODIES DETECTED BY FLOW CYTOMETRY ARE ASSOCIATED WITH TRANSFUSION-RELATED ACUTE LUNG INJURY
PM Kopko, KN Muto, TC Whitted, TG Paglieroni, MR MacKenzie, MA Popovsky, and PV Holland Sacramento Medical Foundation Blood Centers; American Red Cross Blood Services, New England Region

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Transfusion-related acute lung injury (TRALI) is the third most common cause of fatal transfusion reaction. A hallmark symptom is bilateral pulmonary edema that usually develops less than 2 hours after transfusion. Historically, 60-65% of TRALI cases have been associated with granulocyte and/or HLA class I antibodies in transfused blood components that are directed against recipient white cells. We tested recipients and multiple donors from 5 confirmed TRALI cases using an AHG-CDC assay for class I HLA antibody and a flow cytometry based assay capable of distinguishing both HLA class I and class II antibodies. HLA class II antibodies were identified in at least one donor in all 5 TRALI cases studied. Two of these donors also had a class I antibody detected by both AHG-CDC and flow cytometry anti-HLA class I assays. Testing for HLA class I by AHG-CDC alone would have missed three of 5 TRALI cases described above. In conclusion, recipient specific HLA class II antibodies, rather than HLA class I antibodies, may be key in the etiology of TRALI. Sensitive flow-cytometry based assays that can identify both HLA class I and II antibodies are now available and should be used to confirm suspected TRALI.