title: In vivo blockade of CTLA-4 enhances the priming of responsive T cells but fails to prevent the induction of tumor antigen-specific tolerance.
abstract: The efficacy of therapeutic vaccination for the treatment of cancer is limited by peripheral tolerance to tumor antigens. In vivo blockade of CTLA-4, a negative regulator of T cell function, can induce the regression of established tumors and can augment the tumor rejection achieved through therapeutic vaccination. These outcomes may reflect enhanced tumor-specific T cell priming and/or interference with the development of tolerance to tumor antigens. We examined the effect of CTLA-4 blockade on the fate and function of T cells specific for a model tumor antigen in the tumor-bearing host. We found that while CTLA-4 blockade enhanced the priming of responsive T cells, it did not prevent the induction of tolerance to tumor antigens. These results demonstrate that there is a critical window in which the combination of CTLA-4 blockade and vaccination achieves an optimal response, and they point to mechanisms other than CTLA-4 engagement in mediating peripheral T cell tolerance to tumor antigens.
authors.affiliation: Department of Oncology, Johns Hopkins University, Baltimore, MD 21205, USA.
authors.forename: E M
authors.initials: EM
authors.lastname: Sotomayor
authors.forename: I
authors.initials: I
authors.lastname: Borrello
authors.forename: E
authors.initials: E
authors.lastname: Tubb
authors.forename: J P
authors.initials: JP
authors.lastname: Allison
authors.forename: H I
authors.initials: HI
authors.lastname: Levitsky
mesh_terms: D000069594:Abatacept; D000818:Animals; D015703:Antigens, CD / Q000502:physiology; D000943:Antigens, Differentiation / Q000502:physiology*; D000951:Antigens, Neoplasm / Q000276:immunology*; D018122:B7-1 Antigen / Q000502:physiology; D051940:B7-2 Antigen; D060908:CTLA-4 Antigen; D007108:Immune Tolerance; D018796:Immunoconjugates; D008297:Male; D008562:Membrane Glycoproteins / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D009374:Neoplasms, Experimental / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*; D014611:Vaccination
chemical_list: D015703:Antigens, CD; D000943:Antigens, Differentiation; D000951:Antigens, Neoplasm; D018122:B7-1 Antigen; D051940:B7-2 Antigen; D060908:CTLA-4 Antigen; C497965:Cd86 protein, mouse; C556707:Ctla4 protein, mouse; D018796:Immunoconjugates; D008562:Membrane Glycoproteins; D000069594:Abatacept