title: The quantity of TCR signal determines positive selection and lineage commitment of T cells.
abstract: It is generally accepted that the avidity of TCR for self Ag/MHC determines the fate of immature thymocytes. However, the contribution of the quantity of TCR signal to T cell selection has not been well established, particularly in vivo. To address this issue, we analyzed DO-TCR transgenic CD3zeta-deficient (DO-Tg/zetaKO) mice in which T cells have a reduced TCR on the cell surface. In DO-Tg/zetaKO mice, very few CD4 single positive (SP) thymocytes developed, indicating that the decrease in TCR signaling resulted in a failure of positive selection of DO-Tg thymocytes. Administration of the peptide Ag to DO-Tg/zetaKO mice resulted in the generation of functional CD4 SP mature thymocytes in a dose-dependent manner, and, unexpectedly, DO-Tg CD8 SP cells emerged at lower doses of Ag. TCR signal-dependent, sequential commitment from CD8(+) SP to CD4(+) SP was also shown in a class I-restricted TCR-Tg system. These in vivo analyses demonstrate that the quantity of TCR signal directly determines positive and negative selection, and further suggest that weak signal directs positively selected T cells to CD8 lineage and stronger signal to CD4 lineage.
authors.affiliation: Department of Molecular Genetics, Chiba University Graduate School of Medicine, Chiba, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Watanabe
authors.forename: H
authors.initials: H
authors.lastname: Arase
authors.forename: M
authors.initials: M
authors.lastname: Onodera
authors.forename: P S
authors.initials: PS
authors.lastname: Ohashi
authors.forename: T
authors.initials: T
authors.lastname: Saito
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017252:CD3 Complex / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D019070:Cell Lineage / Q000235:genetics / Q000276:immunology; D002478:Cells, Cultured; D015395:Histocompatibility Antigens Class I / Q000502:physiology; D016130:Immunophenotyping; D007274:Injections, Intraperitoneal; D008213:Lymphocyte Activation / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D010047:Ovalbumin / Q000008:administration & dosage / Q000276:immunology; D010446:Peptide Fragments / Q000008:administration & dosage / Q000276:immunology; D017260:Receptor-CD3 Complex, Antigen, T-Cell / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000166:cytology* / Q000276:immunology / Q000378:metabolism*; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology / Q000378:metabolism
chemical_list: D017252:CD3 Complex; C121704:CD3 antigen, zeta chain; D015395:Histocompatibility Antigens Class I; C111390:OVA 323-339; D010446:Peptide Fragments; D017260:Receptor-CD3 Complex, Antigen, T-Cell; D016693:Receptors, Antigen, T-Cell, alpha-beta; D010047:Ovalbumin