Detection of Anti-Non-α-Gal Xenoreactive Antibodies in Human Blood Products

Abstract

Background: Surgical bleeding is a risk in any solid organ transplant, and commonly addressed with the transfusion of human blood product to replace or supplement coagulation factors. It is unknown if these blood products would harm xenotransplanted pig organs in human recipients demonstrating coagulopathy. The aim of this study was to investigate in vitro if blood products such as fresh frozen plasma (FFP) or cryoprecipitate (cryo) contain xenoantibodies capable of cytotoxicity to GTKO pig cells. Methods: We obtained 12 individual single donor (7 FFP and 5 cryo) blood products from our institution blood bank for testing. PBMCs were obtained from a GTKO/hCD55 pig for use as target cells. We performed a series of flow cytometry crossmatch and complement-dependent cytotoxicity assays. Results: We found that all the tested blood products contained some degree of IgM and IgG xenoantibody. Tests using a 1:50 dilution revealed a significant decrease in IgM xenoantibody binding, but an increase the detection of IgG binding. Multiple preparations were capable of GTKO PBMC cytotoxicity but the level of antibody binding and cell death varied by preparation. Conclusions: Both FFP and cryo contain IgM and IgG non-α-Gal xenoantibodies capable of killing GTKO PBMCs, though the level varies by preparation. While some centers utilize a genetic background with mutations in the three enzymes responsible for the known xenoantigens, others are investigating the GTKO pig as a potential option. These results suggest that a center pursuing a human xenotransplantation study with a GTKO genetic background should pre-screen blood products prior to administration.