title: Lack of T cell proliferation without induction of nonresponsiveness after antigen presentation by endothelial cells.
abstract: BACKGROUND
  After priming or reactivation in lymph nodes, T cells recirculate to sites of inflammation, and enter tissues by migrating across activated endothelium. Given that activated endothelial and tissue parenchymal cells express both class I and class II MHC molecules, it is probable that transmigrating T cells encounter cognate antigen on endothelial cells, and on tissue parenchymal cells once they have entered the tissue.
  
  
  METHODS
  In this study the consequences of antigen presentation by endothelial and epithelial cells to human CD4+ T cell clones were analyzed and compared by a two-step culture system.
  
  
  RESULTS
  T cell clones that required B7-mediated costimulation to be activated were found not to be able to proliferate to antigen presented by either endothelial or epithelial cells, unless trans-costimulation was provided by the addition of B7-transfected cells in the cultures. Furthermore, antigen presentation by epithelial cells induced nonresponsiveness in the T cell clones. In contrast, after cognate recognition on endothelial cells, the ability of the T cell clones to proliferate to a subsequent rechallenge with antigen presented on a specialized APC was unaffected.
  
  
  CONCLUSIONS
  These data suggest that endothelial cells have unique properties as antigen-presenting cells, in that they do not influence the subsequent reactivity of cognate T cells.
authors.affiliation: Department of Immunology, Imperial College School of Medicine, London, UK.
authors.forename: F M
authors.initials: FM
authors.lastname: Marelli-Berg
authors.forename: L
authors.initials: L
authors.lastname: Frasca
authors.forename: N
authors.initials: N
authors.lastname: Imami
authors.forename: G
authors.initials: G
authors.lastname: Lombardi
authors.forename: R I
authors.initials: RI
authors.lastname: Lechler
mesh_terms: D000818:Animals; D017951:Antigen Presentation / Q000187:drug effects; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002999:Clone Cells / Q000276:immunology; D018920:Coculture Techniques; D004847:Epithelial Cells / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000502:physiology; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D017493:Leukocyte Common Antigens / Q000032:analysis; D008213:Lymphocyte Activation; D051379:Mice; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*
chemical_list: D000949:Histocompatibility Antigens Class II; D007371:Interferon-gamma; D017493:Leukocyte Common Antigens