GITR glucocorticoid-induced TNFR-related gene, is a member of the TNF receptor superfamily, also known as TNFRSF18,and AITR (in humans).It is expressed at low levels on resting T lymphocytes and at high levels on CD25+CD4+Treg cells.The expression of GITR on T cells can be upregulated upon activation.Interaction of GITR with its ligand (GITRL) has been demonstrated to augment T cell activation, proliferation, cytokine production, as well as MAPKs and NF-kB activation, and abrogate the inhibitory function ofCD25+CD4+ T reg cells.In vivo activation of GITR causes development of autoimmune diseases and restores the suppressed immune response.