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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.

Original publication




Journal article


Eur J Immunol

Publication Date





1247 - 1254


Autoimmunity, CD4 Antigens, CD4-Positive T-Lymphocytes, Cell Communication, Cell Division, Cells, Cultured, Coculture Techniques, Flow Cytometry, Humans, Immune Tolerance, Interferon-gamma, Interleukin-10, Interleukin-2, Ionomycin, Lymphocyte Activation, Mitogens, Receptors, Interleukin-2, T-Lymphocytes, Tetradecanoylphorbol Acetate, Thymus Gland