title: The influence of the thymic environment on the CD4-versus-CD8 T lineage decision.
abstract: T cell receptor signaling is an essential factor regulating thymocyte selection, but the function of the thymic environment in this process is not clear. In mice transgenic for major histocompatibility complex class II-restricted T cell receptors, every thymocyte is potentially selectable for maturation in the CD4 lineage. To address whether selection frequency affects positive selection, we created hematopoietic chimeras with mixtures of selectable and nonselectable precursors. With increased proportions of nonselectable thymocytes, positive selection of MHC class II-specific precursors was enhanced, generating not only CD4 but also CD8 thymocytes. These results indicate that the CD4 versus CD8 fate of selectable precursors can be influenced by the selection potential of its neighbors.
authors.affiliation: Laboratory of Cellular and Molecular Immunology, Building 4, Room 111, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-0420, USA.
authors.forename: Matilde
authors.initials: M
authors.lastname: Canelles
authors.forename: Melissa L
authors.initials: ML
authors.lastname: Park
authors.forename: Owen M
authors.initials: OM
authors.lastname: Schwartz
authors.forename: B J
authors.initials: BJ
authors.lastname: Fowlkes
mesh_terms: D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology; D002450:Cell Communication / Q000276:immunology; D002454:Cell Differentiation / Q000276:immunology / Q000502:physiology*; D019070:Cell Lineage / Q000276:immunology*; D015395:Histocompatibility Antigens Class I / Q000276:immunology; D051379:Mice; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology / Q000502:physiology*
chemical_list: D015395:Histocompatibility Antigens Class I