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Triple-knockout (TKO) pigs may be ideal sources of organs for clinical xenotransplantation because many humans have no preformed antibody to TKO pig cells. Intravenous immunoglobulin (IVIg) is widely used for severe infection or the treatment/prevention of antibody-mediated rejection in allotransplantation. Anti-pig antibodies in IVIg could be harmful in clinical xenotransplantation. It is unknown whether anti-TKO pig antibodies are present in IVIg. The main aim of this study was to investigate in vitro whether IVIg contains anti-TKO pig antibodies with cytotoxic effect to pig cells. Undiluted pooled human serum (HS) and five different commercial preparations of IVIg were tested for IgM and IgG binding to red blood cells (RBCs) from wild-type (WT), α1,3-galactosyltransferase gene-knockout (GTKO), and TKO pigs by flow cytometry. Complement-dependent lysis of IVIg against these pig pRBCs was measured by hemolytic assay. Pooled HS and 4 of 5 IVIg commercial preparations contained anti-pig IgG that bound to WT and GTKO pRBCs, but not to TKO pRBCs. One preparation of IVIg contained antibodies that bound to TKO pRBCs, but there was no cytotoxicity of IVIg to TKO pRBCs. The results suggest that IVIg administration to human recipients of TKO pig grafts would be safe. However, the specific preparation of IVIg would need to be screened before its administration.

Triple-knockout (TKO) pigs (with added protective human transgenes) are likely to be optimal sources of organs for clinical organ xenotransplantation because many humans have minimal or no natural antibody to TKO pig cells. However, Old World monkeys (OWMs) have naturally-existing antibodies directed to TKO cells. We measured anti-pig IgM/IgG binding, and complement-dependent cytotoxicity to wild-type (WT), α1,3-galactosyltransferase gene-knockout (GTKO), and TKO pig peripheral blood mononuclear cells (PBMCs) using sera from humans, several OWMs, and two New World monkeys (NWMs). Furthermore, we compared survival of GTKO (n = 5) and TKO (n = 3) pig kidneys in baboons. OWMs had significantly greater IgM binding and cytotoxicity to TKO PBMCs than humans or NWMs. Mean anti-TKO IgM was significantly higher in OWMs and significantly lower in NWMs than in humans. Cytotoxicity of OWM sera to TKO PBMCs was significantly greater than of human serum, but there was no significant difference between human and NWM sera. The median survival of TKO pig kidneys (4 days) in baboons was significantly shorter than that of GTKO kidneys (136 days) (p