title: Human T-cell proliferation in response to thrombin-activated GTKO pig endothelial cells.
abstract: BACKGROUND
  Thrombin formation is a key feature in the activation of coagulation in pig xenograft recipients. As thrombin is known to activate endothelial and immune cells, we explored whether thrombin activation of pig endothelial cells (EC) was associated with an increased human T-cell response.
  
  
  METHODS
  α1,3-galactosyltransferase gene-knockout (GTKO) pig aortic EC (pAEC) were activated by porcine interferon-gamma (pIFNγ), human (h)IFN-γ, or thrombin. Swine leukocyte antigen (SLA) class I and class II expression were measured. Human peripheral blood mononuclear cells (PBMC) and CD4+ T-cell proliferation in response to activated pAEC, the effect of thrombin on pig CD80/CD86 mRNA, and the effect of thrombin inhibition by hirudin were evaluated.
  
  
  RESULTS
  After pAEC activation, SLA I expression did not change, and only pIFNγ upregulated SLA II expression. PBMC proliferation to pIFNγ- and thrombin-activated pAEC was significantly higher (P < 0.001 and P < 0.01) than to non-activated pAEC. CD4+ T-cell proliferation to pIFNγ- and thrombin-activated pAEC was significantly higher (P < 0.001 and P < 0.01) than to non-activated pAEC. Thrombin inhibition by hirudin reduced thrombin-induced upregulation of pAEC CD86 mRNA, and significantly reduced human PBMC proliferation to pAEC in comparison with thrombin alone (P < 0.05).
  
  
  CONCLUSIONS
  Thrombin upregulates CD86 mRNA on pAEC, which is associated with increased human T-cell proliferation against pAEC. Hirudin reduces CD86 mRNA in thrombin-activated pAEC and is associated with downregulation of the human T-cell proliferative response. The transplantation of organs from GTKO pigs transgenic for human thrombomodulin, and/or endothelial protein C receptor, in addition to therapeutic regulation of thrombin activation may reduce the cellular response to a pig xenograft and thus reduce the need for intensive immunosuppressive therapy.
authors.affiliation: Thomas E. Starzl Transplantation Institute, University of Pittsburgh, PA 15261, USA. ezzemb@upmc.edu
authors.forename: Corin
authors.initials: C
authors.lastname: Ezzelarab
authors.forename: David
authors.initials: D
authors.lastname: Ayares
authors.forename: David K C
authors.initials: DK
authors.lastname: Cooper
authors.forename: Mohamed B
authors.initials: MB
authors.lastname: Ezzelarab
mesh_terms: D000818:Animals; D015478:Antigens, Heterophile / Q000235:genetics; D018122:B7-1 Antigen / Q000235:genetics; D051940:B7-2 Antigen / Q000235:genetics; D001483:Base Sequence; D049109:Cell Proliferation; D018076:DNA, Complementary / Q000235:genetics; D042783:Endothelial Cells / Q000187:drug effects / Q000276:immunology*; D005700:Galactosyltransferases / Q000172:deficiency / Q000235:genetics / Q000276:immunology; D055786:Gene Knockout Techniques; D006629:Hirudins / Q000494:pharmacology; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II / Q000235:genetics / Q000276:immunology; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D008213:Lymphocyte Activation; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034421:Sus scrofa / Q000235:genetics / Q000276:immunology; D013601:T-Lymphocytes / Q000166:cytology* / Q000276:immunology*; D013917:Thrombin / Q000494:pharmacology; D014183:Transplantation, Heterologous
chemical_list: D015478:Antigens, Heterophile; D018122:B7-1 Antigen; D051940:B7-2 Antigen; D018076:DNA, Complementary; D006629:Hirudins; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II; D012333:RNA, Messenger; C438668:swine leukocyte antigen; D007371:Interferon-gamma; D005700:Galactosyltransferases; C530267:alpha-1,3-galactosyltransferase 1, porcine; D013917:Thrombin