title: Antigenic disparity impacts outcome of agonism but not blockade of costimulatory pathways in experimental transplant models.
abstract: Treatment regimens consisting of CTLA-4 Ig/anti-CD154 or agonistic anti-CD28/rapamycin have both been shown to prevent GVHD in fully allogeneic murine model systems. Using a transgenic approach to track the fate of host-reactive T cells in a minor antigen disparity model of GVHD, we found that while treatment with CTLA-4 Ig/anti-CD154 retained efficacy, the costimulation agonist anti-CD28 combined with rapamycin failed to prevent GVHD. Analysis of the host-reactive CD4(+) and CD8(+) T-cell responses revealed that in contrast to CTLA-4Ig/anti-CD154-treated recipients, host-reactive T cells in recipients treated with agonistic anti-CD28/rapamycin displayed enhanced and accelerated T-cell proliferation and failed to undergo activation-induced cell death. An increase in systemic levels of inflammatory cytokines was observed in the anti-CD28/rapamycin-treated recipients of the minor but not major antigen disparity bone marrow transplants. Our results demonstrate the intricacies of costimulatory receptor signaling pathways, and reveal how agonism of the CD28 pathway can have opposing outcomes depending on the degree of antigenic disparity.
authors.affiliation: Department of Surgery, Emory Transplant Center, Emory University, Atlanta, GA, USA.
authors.forename: M L
authors.initials: ML
authors.lastname: Ford
authors.forename: M E
authors.initials: ME
authors.lastname: Wagener
authors.forename: S
authors.initials: S
authors.lastname: Gangappa
authors.forename: T C
authors.initials: TC
authors.lastname: Pearson
authors.forename: C P
authors.initials: CP
authors.lastname: Larsen
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000276:immunology; D000943:Antigens, Differentiation / Q000276:immunology; D016026:Bone Marrow Transplantation / Q000276:immunology*; D018106:CD28 Antigens / Q000276:immunology; D023201:CD40 Ligand / Q000276:immunology; D060908:CTLA-4 Antigen; D007166:Immunosuppressive Agents; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D023421:Models, Animal; D020123:Sirolimus / Q000276:immunology; D016038:Skin Transplantation / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology; D018183:Transplantation Chimera; D014184:Transplantation, Homologous
chemical_list: D015703:Antigens, CD; D000943:Antigens, Differentiation; D018106:CD28 Antigens; D060908:CTLA-4 Antigen; C556707:Ctla4 protein, mouse; D007166:Immunosuppressive Agents; D023201:CD40 Ligand; D020123:Sirolimus