title: CD4+/CD25+ regulatory cells inhibit activation of tumor-primed CD4+ T cells with IFN-gamma-dependent antiangiogenic activity, as well as long-lasting tumor immunity elicited by peptide vaccination.
abstract: CD25(+) regulatory T (T reg) cells suppress the activation/proliferation of other CD4(+) or CD8(+) T cells in vitro. Also, down-regulation of CD25(+) T reg cells enhance antitumor immune responses. In this study, we show that depletion of CD25(+) T reg cells allows the host to induce both CD4(+) and CD8(+) antitumoral responses following tumor challenge. Simultaneous depletion of CD25(+) and CD8(+) cells, as well as adoptive transfer experiments, revealed that tumor-specific CD4(+) T cells, which emerged in the absence of CD25(+) T reg cells, were able to reject CT26 colon cancer cells, a MHC class II-negative tumor. The antitumoral effect mediated by CD4(+) T cells was dependent on IFN-gamma production, which exerted a potent antiangiogenic activity. The capacity of the host to mount this antitumor response is lost once the number of CD25(+) T reg cells is restored over time. However, CD25(+) T reg cell depletion before immunization with AH1 (a cytotoxic T cell determinant from CT26 tumor cells) permits the induction of a long-lasting antitumoral immune response, not observed if immunization is conducted in the presence of regulatory cells. A study of the effect of different levels of depletion of CD25(+) T reg cells before immunization with the peptide AH1 alone, or in combination with a Th determinant, unraveled that Th cells play an important role in overcoming the suppressive effect of CD25(+) T reg on the induction of long-lasting cellular immune responses.
authors.affiliation: Department of Internal Medicine, Medical School, University Clinic and Fundación para la Investigación Médica Aplicada, University of Navarra, Pamplona, Spain.
authors.forename: Noelia
authors.initials: N
authors.lastname: Casares
authors.forename: Laura
authors.initials: L
authors.lastname: Arribillaga
authors.forename: Pablo
authors.initials: P
authors.lastname: Sarobe
authors.forename: Javier
authors.initials: J
authors.lastname: Dotor
authors.forename: Ascensión
authors.initials: A
authors.lastname: Lopez-Diaz de Cerio
authors.forename: Ignacio
authors.initials: I
authors.lastname: Melero
authors.forename: Jesús
authors.initials: J
authors.lastname: Prieto
authors.forename: Francisco
authors.initials: F
authors.lastname: Borrás-Cuesta
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Lasarte
mesh_terms: D019264:Adoptive Transfer; D020533:Angiogenesis Inhibitors / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D000951:Antigens, Neoplasm / Q000008:administration & dosage / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism / Q000637:transplantation; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D019496:Cancer Vaccines / Q000008:administration & dosage / Q000276:immunology; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000098:blood supply / Q000276:immunology* / Q000517:prevention & control; D015536:Down-Regulation / Q000276:immunology*; D018984:Epitopes, T-Lymphocyte / Q000008:administration & dosage / Q000276:immunology; D005260:Female; D007156:Immunologic Memory / Q000276:immunology; D007371:Interferon-gamma / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology*; D008213:Lymphocyte Activation / Q000276:immunology*; D008212:Lymphocyte Depletion; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D009368:Neoplasm Transplantation / Q000276:immunology; D010455:Peptides / Q000008:administration & dosage / Q000276:immunology*; D015375:Receptors, Interleukin-2 / Q000096:biosynthesis*; D016176:T-Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism / Q000637:transplantation
chemical_list: D020533:Angiogenesis Inhibitors; D000951:Antigens, Neoplasm; D019496:Cancer Vaccines; D018984:Epitopes, T-Lymphocyte; D010455:Peptides; D015375:Receptors, Interleukin-2; D007371:Interferon-gamma