Allosensitization Does Not Increase the Risk of Xenoreactivity to α1,3-Galactosyltransferase Gene-Knockout Miniature Swine in Patients on Transplantation Waiting Lists

Background. The recent availability of α1,3-galactosyltransferase knockout (GalT-KO) miniature swine has eliminated anti-Gal antibodies as the major barrier to xenotransplantation, potentially bringing this modality closer to clinical application. Highly-allosensitized patients, who have poor prospects of receiving a suitable cross-match negative human organ, might be the first patients to benefit from xenotransplantation of porcine organs. However, concerns exist regarding cross-reactivity of alloreactive anti-human leukocyte antigen (HLA) antibodies against xenogeneic swine leukocyte antigen (SLA) antigens. We have investigated this question using sera from such patients on GalT-KO target cells. Methods. Using flow cytometry and complement-dependent cytotoxicity (CDC) assays, we have tested a panel of 88 human serum samples from patients awaiting cadaveric renal allotransplantation for reactivity against: 1) human; 2) standard miniature swine; and 3) GalT-KO peripheral blood lymphocytes (PBL) and cultured endothelial cells. Results. Anti-swine IgM and IgG antibody binding, as well as CDC, were significantly attenuated on GalT-KO versus standard swine. No correlation was found between the degree of anti-human panel reactive antibodies (PRA) and xenoreactivity against either standard or GalT-KO miniature swine. Treatment of sera with dithiothreitol (DTT) showed that the majority of remaining lymphocytotoxicity against GalT-KO swine was mediated by preformed IgM antibodies. Patients with high alloreactivity but low anti-GalT-KO xenoreactivity were readily identified. Conclusions. Highly allosensitized patients awaiting renal transplants appear to be at no increased risk of xenosensitization over their non-sensitized cohorts, and could therefore be candidates for xenotransplantation using GalT-KO swine donors.

[1]  D. Sachs,et al.  &agr;1,3-Galactosyltransferase Gene-Knockout Miniature Swine Produce Natural Cytotoxic Anti-Gal Antibodies , 2004, Transplantation.

[2]  D. B. Carter,et al.  Production of (cid:1) -1,3-galactosyltransferase null pigs by means of nuclear transfer with fibroblasts bearing loss of heterozygosity mutations , 2022 .

[3]  K. Kuwaki,et al.  Reduction of anti‐Galα1,3Gal antibodies by infusion of types 2 and 6 gal trisaccharides conjugated to poly‐l‐lysine , 2004 .

[4]  S. Saidman,et al.  Alloantibody and xenoantibody cross-reactivity in transplantation. , 2004, Transplantation.

[5]  C. Blanco,et al.  Cross-Reactivity between Swine Leukocyte Antigen and Human Anti–HLA-Specific Antibodies in Sensitized Patients Awaiting Renal Transplantation , 2003 .

[6]  D. Sachs,et al.  Depletion of anti‐Gal antibodies by the intravenous infusion of Gal type 2 and 6 glycoconjugates in baboons , 2003, Xenotransplantation.

[7]  J. Bradley,et al.  Sensitisation to Swine Leukocyte Antigens in Patients with Broadly Reactive HLA Specific Antibodies , 2002, American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons.

[8]  D. Sachs,et al.  Depletion of anti-gal antibodies in baboons by intravenous therapy with bovine serum albumin conjugated to gal oligosaccharides. , 2002, Transplantation.

[9]  Kwang-Wook Park,et al.  Production of α-1,3-Galactosyltransferase Knockout Pigs by Nuclear Transfer Cloning , 2002, Science.

[10]  C. Bryan,et al.  IgM antibodies identified by a DTT‐ameliorated positive crossmatch do not influence renal graft outcome but the strength of the IgM lymphocytotoxicity is associated with DR phenotype* , 2001, Clinical transplantation.

[11]  H. Asanuma,et al.  ABO-incompatible living-donor kidney transplantation in children. , 2001, Transplantation.

[12]  J. Platt,et al.  BIOPHYSICAL CHARACTERISTICS OF ANTI-GAL&agr;1-3GAL IgM BINDING TO CELL SURFACES: IMPLICATIONS FOR XENOTRANSPLANTATION1 , 2001, Transplantation.

[13]  S. Ménoret,et al.  Interaction of anti-HLA antibodies with pig xenoantigens. , 2000, Transplantation.

[14]  R. Colvin,et al.  Porcine kidney and heart transplantation in baboons undergoing a tolerance induction regimen and antibody adsorption. , 1999, Transplantation.

[15]  T. Howard,et al.  HLA antibodies present in the sera of sensitized patients awaiting renal transplant are also reactive to swine leukocyte antigens. , 1998, Transplantation.

[16]  C. Taylor,et al.  HLA-specific antibodies in highly sensitized patients can cause a positive crossmatch against pig lymphocytes. , 1998, Transplantation.

[17]  T. Sablinski,et al.  Removal of anti-porcine natural antibodies from human and nonhuman primate plasma in vitro and in vivo by a Galalpha1-3Galbeta1-4betaGlc-X immunoaffinity column. , 1998, Transplantation.

[18]  T. Kawai,et al.  Long-term results of ABO-incompatible living kidney transplantation: a single-center experience. , 1998, Transplantation.

[19]  J. Squifflet,et al.  Utility of xenografts: Lack of correlation between PRA and natural antibodies to swine , 1997 .

[20]  M. Sandrin,et al.  Anti-pig IgM antibodies in human serum react predominantly with Gal(alpha 1-3)Gal epitopes. , 1993, Proceedings of the National Academy of Sciences of the United States of America.

[21]  R. Oriol,et al.  Identification of alpha-galactosyl and other carbohydrate epitopes that are bound by human anti-pig antibodies: relevance to discordant xenografting in man. , 1993, Transplant immunology.

[22]  P. Terasaki,et al.  Significance of the positive crossmatch test in kidney transplantation. , 1969, The New England journal of medicine.

[23]  D. Sachs,et al.  Marked prolongation of porcine renal xenograft survival in baboons through the use of α1,3-galactosyltransferase gene-knockout donors and the cotransplantation of vascularized thymic tissue , 2005, Nature Medicine.

[24]  N. Mueller,et al.  Heart transplantation in baboons using α1,3-galactosyltransferase gene-knockout pigs as donors: initial experience , 2005, Nature Medicine.

[25]  K. Kuwaki,et al.  Reduction of anti-Galalpha1,3Gal antibodies by infusion of types 2 and 6 gal trisaccharides conjugated to poly-L-lysine. , 2004, Xenotransplantation.

[26]  A. Centeno Cortés,et al.  Cross-reactivity between swine leukocyte antigen and human anti-HLA-specific antibodies in sensitized patients awaiting renal transplantation. , 2003, Journal of the American Society of Nephrology : JASN.

[27]  D. Sachs,et al.  Will the pig solve the transplantation backlog? , 2002, Annual review of medicine.

[28]  B. N. Day,et al.  Production of α-1,3-Galactosyltransferase Knockout Pigs by Nuclear Transfer Cloning , 2002, Science.

[29]  D. Gjertson.  A multi-factor analysis of kidney regraft outcomes. , 2002, Clinical transplants.

[30]  M. Gnant,et al.  Risk factors for development of panel reactive antibodies and their impact on kidney transplantation outcome. , 1992, Transplant international : official journal of the European Society for Organ Transplantation.