Abstract:Objective To explore the cytotoxicity of human/macaque serum IgG and IgM antibodies on peripheral blood mononuclear cells（PBMC） from different gene-modified porcine to preliminarily screen out the most suitable gene-modified pigs for xenogeneic kidney transplantation of humans or macaques. Methods The α-Gal gene-knockout（GTKO） pigs, α-Gal/β-1, 4N-acetylgalactosaminyltransferase gene-knockout（GTKO/β4GalNT2KO） pigs, α-Gal/cytidine monophosphate-N-acetylneuraminic acid hydroxylase gene knockout（GTKO/CMAHKO） pigs and GTKO/β4GalNT2KO/CMAHKO triple gene knockout（TKO） pigs were constructed. The human protective protein hCD55 was transferred into the three kinds of gene modified pigs respectively. The PBMCs were isolated from each kind of gene-modified pigs.The binding of IgG and IgM antibodies to wild type (WT) pig and various gene-modified pig PBMCs was detected by flow cytometry from 20 macaque sera, the results were expressed by geometric mean fluorescence intensity (Gmean)；at the same time, complement dependent cytotoxicity test (CDC) was used to detect the killing effect of IgG and IgM on different gene modified porcine PBMCs. The serum was collected from 80 people, and then the above-mentioned experiments were repeated. Results （1） The binding of serum IgM from macaques to PBMC from GTKO/β4GalNT2KO/hCD55 pigs was significantly weaker than than that to WT, GTKO/hCD55 and TKO/hCD55 pig PBMCs（Gmean: 7.70 vs 45.05, 7.70 vs 33.21, 7.70 vs 22.52）, which was consistent with the results of CDC assay（Gmean: 9.83% vs 97.79%, 9.83% vs 42.01%, 9.83% vs 47.57%）.（2） The bindings of human serum IgG and IgM to GTKO/CMAHKO and TKO/hCD55 pig PBMCs were low, while the cytotoxic effect of TKO/hCD55 pig PBMCs was the lowest. Conclusion GTKO/β4GalNT2KO/hCD55 pig may be the best donor for pig-macaque xenotransplantation, while TKO pig with the human “protective” gene hCD55 may be the best choice for clinical pig-human xenotransplantation.