title: Both CD45RA+ and CD45RO+ human CD4+ T cells drive direct xenogeneic T-cell responses against porcine aortic endothelial cells.
abstract: BACKGROUND
  Xenogeneic cellular immune responses are mediated by either direct or indirect pathways depending on the participation of donor or host antigen presenting cells, respectively. The contribution of direct response of human T cells, especially memory T cells, to porcine antigen presenting cells is currently unknown. Here, we sought to determine whether human peripheral blood memory/activated phenotype T cells are directly responsive to porcine endothelial cells.
  
  
  METHODS
  Porcine aortic endothelial cells (PAECs) were prepared from Yorkshire or miniature pigs. Highly purified human T cells, including naïve and memory/activated phenotype cells, were incubated with PAECs with or without the addition of exogenous cytokines. T-cell proliferation and T-cell receptor (TCR) Vbeta usage in response to PAECs were analyzed.
  
  
  RESULTS
  Both CD8(+) and CD4(+) T cells responded directly to PAECs and exhibited exclusive responsiveness to SLA class I and class II molecules, respectively. Naïve and memory/activated phenotype CD4(+) T cells responded against PAECs, whereas only naïve phenotype CD8(+) T cells contributed to such a response. In addition, both populations of xenogeneic human CD4(+) T cells exhibited similar and diverse V beta usage.
  
  
  CONCLUSIONS
  Due to the considerable contribution of human CD45RO(+)CD4(+) T cells to the xenoreactivity against PAECs, effective control of xenogeneic memory/activated T-cell responses would significantly affect long-term survival of transplanted grafts.
authors.affiliation: Laboratory of Immunology, Department of Anatomy, College of Medicine, Seoul National University, Seoul, Korea.
authors.forename: Chi Hwa
authors.initials: CH
authors.lastname: Kim
authors.forename: Keunhee
authors.initials: K
authors.lastname: Oh
authors.forename: Dong-Eun
authors.initials: DE
authors.lastname: Kim
authors.forename: Seul Bee
authors.initials: SB
authors.lastname: Lee
authors.forename: Ji Hye
authors.initials: JH
authors.lastname: Yang
authors.forename: Gene
authors.initials: G
authors.lastname: Lee
authors.forename: Jaejin
authors.initials: J
authors.lastname: Cho
authors.forename: Dong-Sup
authors.initials: DS
authors.lastname: Lee
mesh_terms: D000818:Animals; D015478:Antigens, Heterophile / Q000276:immunology*; D001011:Aorta / Q000166:cytology*; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D042783:Endothelial Cells / Q000166:cytology / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D006801:Humans; D017493:Leukocyte Common Antigens / Q000276:immunology*; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000276:immunology; D013552:Swine; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology*
chemical_list: D015478:Antigens, Heterophile; D000949:Histocompatibility Antigens Class II; D016693:Receptors, Antigen, T-Cell, alpha-beta; D017493:Leukocyte Common Antigens