title: Cooperative roles of CTLA-4 and regulatory T cells in tolerance to an islet cell antigen.
abstract: Adoptive transfer of ovalbumin (OVA)-specific T cells from the DO.11 TCR transgenic mouse on a Rag(-/-) background into mice expressing OVA in pancreatic islet cells induces acute insulitis and diabetes only if endogenous lymphocytes, including regulatory T cells, are removed. When wild-type OVA-specific/Rag(-/-) T cells, which are all CD25(-), are transferred into islet antigen-expressing mice, peripheral immunization with OVA in adjuvant is needed to induce diabetes. In contrast, naive CTLA-4(-/-)/Rag(-/-) OVA-specific T cells (also CD25(-)) develop into Th1 effectors and induce disease upon recognition of the self-antigen alone. These results suggest that CTLA-4 functions to increase the activation threshold of autoreactive T cells, because in its absence self-antigen is sufficient to trigger autoimmunity without peripheral immunization. Further, CTLA-4 and regulatory T cells act cooperatively to maintain tolerance, indicating that the function of CTLA-4 is independent of regulatory cells, and deficiency of both is required to induce pathologic immune responses against the islet self-antigen.
authors.affiliation: Department of Pathology, University of California, San Francisco, M590, 505 Parnassus Ave., San Francisco, CA 94143, USA.
authors.forename: Mark P
authors.initials: MP
authors.lastname: Eggena
authors.forename: Lucy S K
authors.initials: LS
authors.lastname: Walker
authors.forename: Vijaya
authors.initials: V
authors.lastname: Nagabhushanam
authors.forename: Luke
authors.initials: L
authors.lastname: Barron
authors.forename: Anna
authors.initials: A
authors.lastname: Chodos
authors.forename: Abul K
authors.initials: AK
authors.lastname: Abbas
mesh_terms: D000818:Animals; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000276:immunology*; D001324:Autoantigens / Q000276:immunology; D015551:Autoimmunity; D060908:CTLA-4 Antigen; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics / Q000276:immunology; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics / Q000276:immunology*; D007108:Immune Tolerance / Q000276:immunology*; D007515:Islets of Langerhans / Q000276:immunology*; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D010047:Ovalbumin / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D015703:Antigens, CD; D000943:Antigens, Differentiation; D001324:Autoantigens; D060908:CTLA-4 Antigen; C556707:Ctla4 protein, mouse; D004268:DNA-Binding Proteins; C499308:Rag2 protein, mouse; C064655:V(D)J recombination activating protein 2; D010047:Ovalbumin