Antigen-induced regulatory T cells: 3 mechanisms of suppression. (A) After antigen-specific recognition of the target DCs, Trs inhibit CD40, CD80, and CD86 up-regulation. (B) After recognition of its specific antigen, Tr secretes IL10 and/or TGFβ. (C) Tr activates the FAS–FAS ligand cytolytic pathway to kill the effector target T cell (T) after its specific recognition.