Impact of Swine Leukocyte Antigen on renal endothelial cells in pig-to-non-human primate xenotransplantation in vitro

Abstract

Abstract BACKBROUND The development of a pig lacking the GGTA1, B4GNT2 and CMAH genes (TKO) that produce the three known glycan xenoantigens has provided the decreased background human antibody binding to TKO cells. It can be easily detected for antibody binding to sufficiently low levels of any additional xenoantigens expressed on the pig cells, including swine leukocyte antigen (SLA). The object of this study is to evaluate the role of SLA class I and II in the pig-to-non-human primate (NHP) xenotransplantation in vitro at an organ-specific cell level using renal endothelial cells (REC). METHODS Characteristics of genetically-edited REC and Interferon gamma (IFN-γ)-activated REC were analyzed using flow cytometry. Rhesus IgG/IgM binding to REC with or without SLA class I, or SLA class II expression were examined using flow cytometric crossmatch and complement-dependent cytotoxicity assay (CDC). RESULTS SLA I-deficient REC with GGTA1/B4GNT2/CMAH TKO background had significantly lower Levels of antibody binding (p=0.02 and p=0.0001, respectively for IgG and IgM) using 25% rhesus sera (n=14). SLA class II expression on SLA I-deficient GGTA1/B4GNT2 REC was induced following 3-day treatment of IFN-γ. These cells with SLA class II expression had significantly increased IgM binding by crossmatch (p=0.002), and had significantly high levels of cell lysis by CDC assay (p<0.0001) using 25% rhesus sera (n=11). CONCLUSIONS Gene editing of the SLA class I and II on pig organs might protect against chronic antibody-mediated rejection via reducing antibody binding to REC in pig-to-NHP renal xenotransplantation. Porcine REC cell lines will be a useful reagent for the further study of xenoimmunology. Supported by Partial 5R01AI126322