title: Immunologic self-tolerance maintained by activated T cells expressing IL-2 receptor alpha-chains (CD25). Breakdown of a single mechanism of self-tolerance causes various autoimmune diseases.
abstract: Approximately 10% of peripheral CD4+ cells and less than 1% of CD8+ cells in normal unimmunized adult mice express the IL-2 receptor alpha-chain (CD25) molecules. When CD4+ cell suspensions prepared from BALB/c nu/+ mice lymph nodes and spleens were depleted of CD25+ cells by specific mAb and C, and then inoculated into BALB/c athymic nude (nu/nu) mice, all recipients spontaneously developed histologically and serologically evident autoimmune diseases (such as thyroiditis, gastritis, insulitis, sialoadenitis, adrenalitis, oophoritis, glomerulonephritis, and polyarthritis); some mice also developed graft-vs-host-like wasting disease. Reconstitution of CD4+CD25+ cells within a limited period after transfer of CD4+CD25- cells prevented these autoimmune developments in a dose-dependent fashion, whereas the reconstitution several days later, or inoculation of an equivalent dose of CD8+ cells, was far less efficient for the prevention. When nu/nu mice were transplanted with allogeneic skins or immunized with xenogeneic proteins at the time of CD25- cell inoculation, they showed significantly heightened immune responses to the skins or proteins, and reconstitution of CD4+CD25+ cells normalized the responses. Taken together, these results indicate that CD4+CD25+ cells contribute to maintaining self-tolerance by down-regulating immune response to self and non-self Ags in an Ag-nonspecific manner, presumably at the T cell activation stage; elimination/reduction of CD4+CD25+ cells relieves this general suppression, thereby not only enhancing immune responses to non-self Ags, but also eliciting autoimmune responses to certain self-Ags. Abnormality of this T cell-mediated mechanism of peripheral tolerance can be a possible cause of various autoimmune diseases.
authors.affiliation: Precursory Research for Embryonic Science and Technology (PRESTO), Research and Development Corporation of Japan (JRDC), Tsukuba Life Science Center.
authors.forename: S
authors.initials: S
authors.lastname: Sakaguchi
authors.forename: N
authors.initials: N
authors.lastname: Sakaguchi
authors.forename: M
authors.initials: M
authors.lastname: Asano
authors.forename: M
authors.initials: M
authors.lastname: Itoh
authors.forename: M
authors.initials: M
authors.lastname: Toda
mesh_terms: D000818:Animals; D001327:Autoimmune Diseases / Q000209:etiology / Q000276:immunology* / Q000517:prevention & control; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism / Q000637:transplantation; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D005260:Female; D006086:Graft vs Host Disease / Q000209:etiology / Q000276:immunology* / Q000517:prevention & control; D016219:Immunotherapy, Adoptive / Q000009:adverse effects; D007376:Interleukin-2 / Q000502:physiology*; D007519:Isoantigens / Q000276:immunology; D008212:Lymphocyte Depletion; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D015375:Receptors, Interleukin-2 / Q000096:biosynthesis / Q000502:physiology*; D017634:Self Tolerance / Q000276:immunology*; D016038:Skin Transplantation / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism / Q000637:transplantation
chemical_list: D007376:Interleukin-2; D007519:Isoantigens; D015375:Receptors, Interleukin-2