title: CTLA-4 on alloreactive CD4 T cells interacts with recipient CD80/86 to promote tolerance.
abstract: Although the inhibitory receptor CTLA-4 (CD152) has been implicated in peripheral CD4 T-cell tolerance, its mechanism of action remains poorly defined. We analyzed mechanisms of CD4 cell tolerance in a model of tolerance induction involving establishment of mixed hematopoietic chimerism in recipients of fully MHC-mismatched allogeneic bone marrow cells with anti-CD154 mAb. Animals lacking CD80 and CD86 failed to achieve chimerism. We detected no T cell-intrinsic requirement for CD28 for chimerism induction. However, a CD4 T cell-intrinsic signal through CTLA-4 was shown to be essential within the first 48 hours of exposure to alloantigen for the establishment of tolerance and mixed chimerism. This signal must be provided by a recipient CD80/86(+) non-T-cell population. Donor CD80/86 expression was insufficient to achieve tolerance. Together, our findings demonstrate a surprising role for interactions of CTLA-4 expressed by alloreactive peripheral CD4 T cells with CD80/86 on recipient antigen-presenting cells (APCs) in the induction of early tolerance, suggesting a 3-cell tolerance model involving directly alloreactive CD4 cells, donor antigen-expressing bone marrow cells, and recipient antigen-presenting cells. This tolerance is independent of regulatory T cells and culminates in the deletion of directly alloreactive CD4 T cells.
authors.affiliation: Bone Marrow Transplantation Section, Transplantation Biology Research Center, Massachusetts General Hospital/Harvard Medical School, Boston, MA 02129, USA.
authors.forename: Josef
authors.initials: J
authors.lastname: Kurtz
authors.forename: Forum
authors.initials: F
authors.lastname: Raval
authors.forename: Casey
authors.initials: C
authors.lastname: Vallot
authors.forename: Jayden
authors.initials: J
authors.lastname: Der
authors.forename: Megan
authors.initials: M
authors.lastname: Sykes
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D015703:Antigens, CD / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D018122:B7-1 Antigen / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D051940:B7-2 Antigen / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D016026:Bone Marrow Transplantation / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D023201:CD40 Ligand / Q000276:immunology; D016827:CD8 Antigens / Q000276:immunology; D060908:CTLA-4 Antigen; D006084:Graft Rejection / Q000276:immunology; D007108:Immune Tolerance / Q000276:immunology*; D007519:Isoantigens / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D011828:Radiation Chimera; D015398:Signal Transduction / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D018122:B7-1 Antigen; D051940:B7-2 Antigen; D016827:CD8 Antigens; D060908:CTLA-4 Antigen; C497965:Cd86 protein, mouse; C556707:Ctla4 protein, mouse; D007519:Isoantigens; D023201:CD40 Ligand