The critical contribution of TGF-β to the induction of Foxp3 expression and regulatory T cell function

Stimulation of mouse CD4(+) T cells in the presence of TGF-beta results in the expression of Foxp3 and induction of T-reg function. Stimulation of human CD4(+) T cells under similar conditions results in the expression of Foxp3, but the cells lack regulatory cell function. TGF-beta expressed on the surface of T-reg also induces Foxp3 expression and T-reg function in responder cells. Both of these mechanisms may play a role in vivo in the induction of antigen-specific extra-thymic T-reg.