title: Positive selection by purified MHC class II+ thymic epithelial cells in vitro: costimulatory signals mediated by B7 are not involved.
abstract: We have investigated the possibility that the costimulatory signals required for activation of mature T cells also play a role in providing differentiation signals for positive selection during T-cell development. We show that purified MHC Class II+ thymic epithelial cells are able to support positive selection in vitro but lack both the functional capacity to deliver costimulatory signals and expression of the costimulatory ligand B7. Our results suggest that the additional signals provided by costimulatory ligands are not required for TCR-mediated positive selection, although other ancillary signals provided by thymic epithelial cells may be involved.
authors.affiliation: Department of Anatomy, Medical School, University of Birmingham, U.K.
authors.forename: E J
authors.initials: EJ
authors.lastname: Jenkinson
authors.forename: G
authors.initials: G
authors.lastname: Anderson
authors.forename: N C
authors.initials: NC
authors.lastname: Moore
authors.forename: C A
authors.initials: CA
authors.lastname: Smith
authors.forename: J J
authors.initials: JJ
authors.lastname: Owen
mesh_terms: D000818:Animals; D002450:Cell Communication; D002454:Cell Differentiation; D002478:Cells, Cultured; D004848:Epithelium / Q000196:embryology / Q000276:immunology; D005260:Female; D000949:Histocompatibility Antigens Class II / Q000378:metabolism*; D008024:Ligands; D051379:Mice; D008807:Mice, Inbred BALB C; D011247:Pregnancy; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000166:cytology* / Q000276:immunology; D013950:Thymus Gland / Q000196:embryology* / Q000276:immunology
chemical_list: D000949:Histocompatibility Antigens Class II; D008024:Ligands