Figure 1.

Functions of regulatory T cells. (A) Interaction of pro-inflammatory IL-2 with CD25 for the differentiation and maintenance of Tregs and stabilization of FoxP3. (B) Production of anti-inflammatory cytokines including IL-10, TGFβ, and cAMP to create an immunotolerant environment. (C) Secretion of granzymes and perforins causes apoptosis of CD4+T effector cells. (D) CTLA4 interacts with co-stimulatory CD80 and CD86 ligands on the surface of APCs and activates IDO in them which depletes tryptophan in the local environment and consequently inhibits the proliferation of T cells.