title: Preventing human CD8+ cytotoxic T lymphocyte-mediated cytotoxicity against swine endothelial cells by overexpression of human decoy Fas antigen.
abstract: Although the birth of homozygous alpha1, 3 galactosyltransferase gene-knockout pigs raised hopes for an imminent breakthrough in the prevention in the antibody-mediated rejection of pig to human discordant xenotransplants, human CD8(+) cytotoxic T lymphocyte (CTL)-mediated killing may represent a new immunological barrier to long-term survival in xenograft recipients. In this study, we demonstrated that the cytotoxicity of human CD8(+) CTL against swine endothelial cells (SEC) is highly detrimental and mediated at least in part by the Fas/FasL pathway. To prevent this CTL-mediated xenocytotoxicity, we overexpressed the human decoy Fas antigen, which does not contain a death domain in its cytoplasmic region, by means of binding competition with endogenous pig Fas antigen on SEC for the common ligand, human FasL. Furthermore, we generated a membrane-bound form of human FasL that cannot be cleaved by a putative metalloproteinase to produce a soluble form, which was assessed as an inhibitor of CTL cytotoxicity. Both human decoy Fas and membrane-bound FasL were effective to prevent CTL-mediated killing, suggesting that these novel molecules may represent a step forward toward preventing CD8(+) CTL-mediated xenograft rejection. The combined expression of both molecules may be more beneficial to protect xenograft cells.
authors.affiliation: Department of Surgery (E1), Osaka University Graduate School of Medicine, Osaka, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Kawamoto
authors.forename: M
authors.initials: M
authors.lastname: Tanemura
authors.forename: T
authors.initials: T
authors.lastname: Ito
authors.forename: F
authors.initials: F
authors.lastname: Uchikoshi
authors.forename: K
authors.initials: K
authors.lastname: Shimada
authors.forename: T
authors.initials: T
authors.lastname: Nishida
authors.forename: H
authors.initials: H
authors.lastname: Matsuda
mesh_terms: D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D004730:Endothelium, Vascular / Q000276:immunology / Q000637:transplantation*; D005700:Galactosyltransferases / Q000172:deficiency / Q000235:genetics; D017353:Gene Deletion; D006801:Humans; D013552:Swine; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D014183:Transplantation, Heterologous; D019014:fas Receptor / Q000235:genetics*
chemical_list: D019014:fas Receptor; D005700:Galactosyltransferases