title: Positive and negative thymocyte selection induced by different concentrations of a single peptide.
abstract: T lymphocyte maturation is dependent on interactions between the T cell receptor (TCR) expressed on the developing thymocyte and intrathymic major histocompatibility complex (MHC)-peptide ligands. The relation between the peptide-MHC complex that results in negative or positive selection has not been identified. Here, the requirements for the maturation of thymocytes expressing a defined transgenic TCR specific for a viral peptide are studied in fetal thymic organ culture. Low concentrations of the viral peptide antigen recognized by this transgenic TCR can mediate positive selection, whereas high concentrations result in thymocyte tolerance. These findings support the affinity-avidity model of thymocyte selection.
authors.affiliation: Ontario Cancer Institute, Department of Medical Biophysics, Toronto, Canada.
authors.forename: E
authors.initials: E
authors.lastname: Sebzda
authors.forename: V A
authors.initials: VA
authors.lastname: Wallace
authors.forename: J
authors.initials: J
authors.lastname: Mayer
authors.forename: R S
authors.initials: RS
authors.lastname: Yeung
authors.forename: T W
authors.initials: TW
authors.lastname: Mak
authors.forename: P S
authors.initials: PS
authors.lastname: Ohashi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015704:CD4 Antigens / Q000032:analysis; D016827:CD8 Antigens / Q000032:analysis; D006183:H-2 Antigens; D008213:Lymphocyte Activation; D008217:Lymphocytic choriomeningitis virus; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D009924:Organ Culture Techniques; D010446:Peptide Fragments / Q000276:immunology*; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D013950:Thymus Gland / Q000196:embryology / Q000276:immunology*; D014764:Viral Proteins / Q000276:immunology*
chemical_list: D015704:CD4 Antigens; D016827:CD8 Antigens; D006183:H-2 Antigens; D010446:Peptide Fragments; D011948:Receptors, Antigen, T-Cell; D014764:Viral Proteins