title: Regulation of T cell autoreactivity to MHC class II by controlling CD80 (B7-1) expression on B cells.
abstract: Regulatory mechanisms of T cell autoreactivity to MHC class II molecules were studied in transgenic (Tg) mice with auto-I-Ak-reactive TCR alphabeta transgenes (designated as MS Tg mice). Our previous study revealed that the T cell tolerance established in autoreactive MS Tg mice was not due to either clonal deletion in the thymus, anergy or an active suppression in the periphery. We proposed a novel form of self tolerance termed 'clonal insufficiency', where autoreactive T cells were conditionally rendered unresponsiveness to self antigen in vivo, although retaining full potential reactivity in in vitro conditions. Here, we investigated the role of co-stimulatory molecules for the induction of self tolerance with 'clonal insufficiency'. MS Tg mice were mated with CD80 (B7-1) Tg mice in which B cells exclusively and constitutively expressed CD80 molecules. Both MS Tg mice and CD80 Tg mice by themselves showed no evidence for activation of T cells and B cells, whereas MS x CD80 double-Tg mice with a H-2k background revealed an abnormal increase in the number of splenocytes and in the expression of activation markers (CD69 and CD25) on CD4 T cells in the spleen. These results indicated that the self tolerance established in MS Tg mice involved a down-regulation of CD80 molecules on B cells in vivo, resulting in a failure of sufficient T-B interactions. In addition, the serum concentration of IL-10, one of the down-regulators of CD80 expression, was found to be increased significantly in MS Tg mice. The autoreactivity of MS Tg T cells detected in vitro was significantly blocked by recombinant IL-10. Thus, IL-10-mediated down-regulation of CD80 on B cells was suggested to be involved in the clonal insufficiency in MS Tg mice in vivo.
authors.affiliation: Research Institute for Biological Sciences and Faculty of Pharmaceutical Sciences, Science University of Tokyo, Chiba, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Hasegawa
authors.forename: Y
authors.initials: Y
authors.lastname: Ueno
authors.forename: M
authors.initials: M
authors.lastname: Yamashita
authors.forename: T
authors.initials: T
authors.lastname: Nakayama
authors.forename: T
authors.initials: T
authors.lastname: Tada
mesh_terms: D000818:Animals; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D001324:Autoantigens / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D018122:B7-1 Antigen / Q000502:physiology*; D018791:CD4 Lymphocyte Count; D015496:CD4-Positive T-Lymphocytes; D018414:CD8-Positive T-Lymphocytes; D005434:Flow Cytometry; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D007108:Immune Tolerance; D016753:Interleukin-10 / Q000096:biosynthesis; D037181:Lectins, C-Type; D008213:Lymphocyte Activation; D051379:Mice; D008809:Mice, Inbred C3H; D008822:Mice, Transgenic; D015375:Receptors, Interleukin-2; D013154:Spleen / Q000166:cytology; D016176:T-Lymphocyte Subsets; D013601:T-Lymphocytes / Q000276:immunology*; D018418:Th2 Cells / Q000276:immunology; D000099192:CD69 Antigens
chemical_list: D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D001324:Autoantigens; D018122:B7-1 Antigen; D000949:Histocompatibility Antigens Class II; D016753:Interleukin-10; D037181:Lectins, C-Type; D015375:Receptors, Interleukin-2; D000099192:CD69 Antigens