title: HLA-E/human beta2-microglobulin transgenic pigs: protection against xenogeneic human anti-pig natural killer cell cytotoxicity.
abstract: BACKGROUND
  Natural killer (NK) cells participate in pig-to-primate xenograft rejection both by antibody-dependent and -independent mechanisms. A majority of human NK cells express the inhibitory receptor CD94/NKG2A, which binds specifically to human leukocyte antigen (HLA)-E, a trimeric complex consisting of the HLA-E heavy chain, beta2-microglobulin (beta2m), and a peptide derived from the leader sequence of some major histocompatibility complex class I molecules.
  
  
  METHODS
  To use this mechanism for protection of pig tissues against human NK cell-mediated cytotoxicity, we generated transgenic pigs by pronuclear microinjection of genomic fragments of HLA-E with an HLA-B7 signal sequence and of human beta2-microglobulin (hubeta2m) into zygotes.
  
  
  RESULTS
  Three transgenic founder pigs were generated. Northern blot analysis of RNA from peripheral blood mononuclear cells revealed the presence of the expected transcript sizes for both transgenes in two of the three founders. The founder with the highest expression and his offspring were characterized in detail. Fluorescence-activated cell sorting (FACS) and Western blot analyses demonstrated consistent expression of HLA-E and hubeta2m in peripheral blood mononuclear cells. Immunohistochemistry revealed the presence of HLA-E and hubeta2m on endothelial cells of many organs, including heart and kidney. In vitro studies showed that lymphoblasts and endothelial cells derived from HLA-E/hubeta2m transgenic pigs are effectively protected against human NK cell-mediated cytotoxicity, depending on the level of CD94/NKG2A expression on the NK cells. Further, HLA-E/hubeta2m expression on porcine endothelial cells inhibited the secretion of interferon (IFN)-gamma by co-cultured human NK cells.
  
  
  CONCLUSIONS
  This novel approach against cell-mediated xenogeneic responses has important implications for the generation of multitransgenic pigs as organ donors for clinical xenotransplantation.
authors.affiliation: Department of Biology II, Anthropology and Human Genetics, LMU Munich, Planegg-Martinsried, Germany. Elisabeth.Weiss@lmu.de
authors.forename: Elisabeth H
authors.initials: EH
authors.lastname: Weiss
authors.forename: Benjamin G
authors.initials: BG
authors.lastname: Lilienfeld
authors.forename: Sigrid
authors.initials: S
authors.lastname: Müller
authors.forename: Elfriede
authors.initials: E
authors.lastname: Müller
authors.forename: Nadja
authors.initials: N
authors.lastname: Herbach
authors.forename: Barbara
authors.initials: B
authors.lastname: Kessler
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Wanke
authors.forename: Reinhard
authors.initials: R
authors.lastname: Schwinzer
authors.forename: Jörg D
authors.initials: JD
authors.lastname: Seebach
authors.forename: Eckhard
authors.initials: E
authors.lastname: Wolf
authors.forename: Gottfried
authors.initials: G
authors.lastname: Brem
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D002465:Cell Movement / Q000276:immunology; D002478:Cells, Cultured; D003602:Cytotoxicity, Immunologic / Q000276:immunology*; D042783:Endothelial Cells / Q000276:immunology / Q000378:metabolism; D006680:HLA Antigens / Q000276:immunology*; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D006801:Humans; D007694:Killer Cells, Natural / Q000166:cytology / Q000276:immunology*; D009928:Organ Specificity; D013552:Swine / Q000276:immunology*; D014183:Transplantation, Heterologous / Q000276:immunology*; D001613:beta 2-Microglobulin / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D000097625:HLA-E Antigens
chemical_list: D006680:HLA Antigens; D015395:Histocompatibility Antigens Class I; D001613:beta 2-Microglobulin; D000097625:HLA-E Antigens