title: Cell contact-dependent immunosuppression by CD4(+)CD25(+) regulatory T cells is mediated by cell surface-bound transforming growth factor beta.
abstract: CD4(+)CD25(+) T cells have been identified as a population of immunoregulatory T cells, which mediate suppression of CD4(+)CD25(-) T cells by cell-cell contact and not secretion of suppressor cytokines. In this study, we demonstrated that CD4(+)CD25(+) T cells do produce high levels of transforming growth factor (TGF)-beta1 and interleukin (IL)-10 compared with CD4(+)CD25(-) T cells when stimulated by plate-bound anti-CD3 and soluble anti-CD28 and/or IL-2, and secretion of TGF-beta1 (but not other cytokines), is further enhanced by costimulation via cytotoxic T lymphocyte-associated antigen (CTLA)-4. As in prior studies, we found that CD4(+)CD25(+) T cells suppress proliferation of CD4(+)CD25(-) T cells; however, we observed here that such suppression is abolished by the presence of anti-TGF-beta. In addition, we found that CD4(+)CD25(+) T cells suppress B cell immunoglobulin production and that anti-TGF-beta again abolishes such suppression. Finally, we found that stimulated CD4(+)CD25(+) T cells but not CD4(+)CD25(-) T cells express high and persistent levels of TGF-beta1 on the cell surface. This, plus the fact that we could find no evidence that a soluble factor mediates suppression, strongly suggests that CD4(+)CD25(+) T cells exert immunosuppression by a cell-cell interaction involving cell surface TGF-beta1.
authors.affiliation: Mucosal Immunity Section, Laboratory of Clinical Investigation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: K
authors.initials: K
authors.lastname: Nakamura
authors.forename: A
authors.initials: A
authors.lastname: Kitani
authors.forename: W
authors.initials: W
authors.lastname: Strober
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D000917:Antibody Formation; D001402:B-Lymphocytes / Q000276:immunology; D017252:CD3 Complex / Q000276:immunology; D015704:CD4 Antigens / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002450:Cell Communication / Q000276:immunology*; D002462:Cell Membrane / Q000276:immunology / Q000502:physiology*; D002478:Cells, Cultured; D016207:Cytokines / Q000096:biosynthesis*; D005260:Female; D005434:Flow Cytometry; D007378:Interleukins / Q000096:biosynthesis; D008213:Lymphocyte Activation / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D051381:Rats; D015375:Receptors, Interleukin-2 / Q000276:immunology*; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology* / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000096:biosynthesis / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D017252:CD3 Complex; D015704:CD4 Antigens; D016207:Cytokines; D007378:Interleukins; D015375:Receptors, Interleukin-2; D016212:Transforming Growth Factor beta