title: Different mechanisms of cardiac allograft rejection in wildtype and CD28-deficient mice.
abstract: Although CD28 blockade results in long-term cardiac allograft survival in wildtype mice, CD28-deficient mice effectively reject heart allografts. This study compared the mechanisms of allogeneic responses in wildtype and CD28-deficient mice. Adoptive transfer of purified CD28-deficient T cells into transplanted nude mice resulted in graft rejection. However, this model demonstrated that the allogeneic T cell function was severely impaired when compared with wildtype T cells, despite similar survival kinetics. Cardiac allograft rejection depended on both CD4+ and CD8+ T cell subsets in CD28-deficient mice, whereas only CD4+ T cells were necessary in wildtype recipients. These results suggested that CD8+ T cells were more important in CD28-deficient than wildtype mice. In addition to the CD8+ T cell requirement, allograft rejection in CD28-deficient mice was dependent on a sustained presence of CD4+ T cells, whereas it only required the initial presence of CD4+ T cells in wildtype mice. Taken together, these data suggest that CD4+ T cells from CD28-deficient mice have impaired responses to alloantigen in vivo, thus requiring long-lasting cooperation with CD8+ T cell responses to facilitate graft rejection. These results may help to explain the failure to promote graft tolerance in some preclinical and clinical settings.
authors.affiliation: Ben May Institute for Cancer Research, The University of Chicago, IL 60637, USA.
authors.forename: G L
authors.initials: GL
authors.lastname: Szot
authors.forename: P
authors.initials: P
authors.lastname: Zhou
authors.forename: I
authors.initials: I
authors.lastname: Rulifson
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: Z
authors.initials: Z
authors.lastname: Guo
authors.forename: O
authors.initials: O
authors.lastname: Kim
authors.forename: K A
authors.initials: KA
authors.lastname: Newel
authors.forename: J R
authors.initials: JR
authors.lastname: Thistlethwaite
authors.forename: J A
authors.initials: JA
authors.lastname: Bluestone
authors.forename: M L
authors.initials: ML
authors.lastname: Alegre
mesh_terms: D000069594:Abatacept; D019264:Adoptive Transfer; D000818:Animals; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000276:immunology; D018106:CD28 Antigens / Q000235:genetics / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D060908:CTLA-4 Antigen; D006084:Graft Rejection / Q000276:immunology*; D006085:Graft Survival / Q000276:immunology; D016027:Heart Transplantation / Q000276:immunology*; D018796:Immunoconjugates; D007141:Immunoglobulin Fc Fragments / Q000276:immunology; D051379:Mice; D018345:Mice, Knockout; D016176:T-Lymphocyte Subsets / Q000276:immunology; D013997:Time Factors; D014184:Transplantation, Homologous / Q000473:pathology
chemical_list: D015703:Antigens, CD; D000943:Antigens, Differentiation; D018106:CD28 Antigens; D060908:CTLA-4 Antigen; C556707:Ctla4 protein, mouse; D018796:Immunoconjugates; D007141:Immunoglobulin Fc Fragments; D000069594:Abatacept