title: Facilitation of beta selection and modification of positive selection in the thymus of PD-1-deficient mice.
abstract: PD-1 is an immunoglobulin superfamily member bearing an immunoreceptor tyrosine-based inhibitory motif, and disruption of the PD-1 gene results in the development of lupus-like autoimmune diseases. In this study, we examined effects of the PD-1 deficiency on the thymocyte differentiation at the clonal level using T cell receptor (TCR)-beta (Vbeta8) and TCR-alpha/beta (H-Y and 2C) transgenic mice. In these TCR transgenic lines, PD-1 expression in the thymus was variably augmented, but as in the normal mice, confined largely to the CD4(-)CD8(-) thymocytes. The transgenic mice crossed with PD-1(-/)- mice in the neutral genetic backgrounds exhibited selective increase in the CD4(+)CD8(+) (DP) population with little effect on other thymocytes subsets. Similarly, the absence of PD-1 facilitated expansion of DP thymocytes in recombination activating gene (RAG)-2(-/)- mice by anti-CD3epsilon antibody injection. On the other hand, H-Y or 2C transgenic PD-1(-/)- mice with the positively selecting background showed significantly reduced efficiency for the generation of CD8(+) single positive cells bearing the transgenic TCR-alpha/beta in spite of the increased DP population. These results collectively indicate that PD-1 negatively regulates the beta selection and modulates the positive selection, and suggest that PD-1 deficiency may lead to the significant alteration of mature T cell repertoire.
authors.affiliation: Department of Medical Chemistry, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Nishimura
authors.forename: T
authors.initials: T
authors.lastname: Honjo
authors.forename: N
authors.initials: N
authors.lastname: Minato
mesh_terms: D000818:Animals; D001327:Autoimmune Diseases / Q000209:etiology; D015496:CD4-Positive T-Lymphocytes; D018414:CD8-Positive T-Lymphocytes; D004268:DNA-Binding Proteins / Q000235:genetics; D015333:Gene Rearrangement, beta-Chain T-Cell Antigen Receptor; D007136:Immunoglobulins / Q000235:genetics / Q000276:immunology*; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics*; D012641:Selection, Genetic; D013950:Thymus Gland / Q000276:immunology*
chemical_list: D004268:DNA-Binding Proteins; D007136:Immunoglobulins; C499308:Rag2 protein, mouse; D016693:Receptors, Antigen, T-Cell, alpha-beta; C075784:T cell receptor Vbeta8; C064655:V(D)J recombination activating protein 2