title: Human CD4(+)CD25(+) thymocytes and peripheral T cells have immune suppressive activity in vitro.
abstract: CD4(+)CD25(+) T cells in mice and rats are capable of transferring protection against organ-specific autoimmune disease and colitis and suppressing the proliferation of other T cells after polyclonal stimulation in vitro. Here we describe the existence in humans of CD4(+)CD25(+) T cells with the same in vitro characteristics. CD4(+)CD8(-)CD25(+) T cells are present in both the thymus and peripheral blood of humans ( approximately 10 % of CD4(+)CD8(-) T cells), proliferate poorly in response to mitogenic stimulation and suppress the proliferation of CD4(+)CD25(-) cells in co-culture. This suppression requires cell contact and can be overcome by the addition of exogenous IL-2. CD4(+)CD25(+) cells from thymus and blood were poor producers of IL-2 and IFN-gamma, and suppressed the levels of these cytokines produced by CD4(+)CD25(-) cells. However, CD4(+)CD25(+) PBL produced higher levels of IL-4 and similar amounts of IL-10 as CD4(+)CD25(-) cells. Regulatory CD4(+)CD25(+) T cells have an activated phenotype in the thymus with expression of CTLA-4 and CD122 (IL-2Rbeta). The fact that CD4(+)CD25(+) regulatory T cells are present with a similar frequency in the thymus of humans, rats and mice, suggests that the role of these cells in the maintenance of immunological tolerance is an evolutionarily conserved mechanism.
authors: Sir William Dunn School of Pathology, University of Oxford, Oxford, GB. leighs@molbiol.ox.ac.uk
authors: L A
authors: LA
authors: Stephens
authors: C
authors: C
authors: Mottet
authors: D
authors: D
authors: Mason
authors: F
authors: F
authors: Powrie
mesh_terms: D015551:Autoimmunity / Q000276:immunology; D015704:CD4 Antigens / Q000276:immunology / Q000378:metabolism*; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D002450:Cell Communication / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D018920:Coculture Techniques; D005434:Flow Cytometry; D006801:Humans; D007108:Immune Tolerance / Q000276:immunology*; D007371:Interferon-gamma / Q000096:biosynthesis / Q000276:immunology; D016753:Interleukin-10 / Q000096:biosynthesis / Q000276:immunology; D007376:Interleukin-2 / Q000096:biosynthesis / Q000276:immunology; D015759:Ionomycin / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects; D008934:Mitogens / Q000276:immunology; D015375:Receptors, Interleukin-2 / Q000276:immunology / Q000378:metabolism*; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013950:Thymus Gland / Q000166:cytology* / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism
chemical_list: D015704:CD4 Antigens; D007376:Interleukin-2; D008934:Mitogens; D015375:Receptors, Interleukin-2; D016753:Interleukin-10; D015759:Ionomycin; D007371:Interferon-gamma; D013755:Tetradecanoylphorbol Acetate