GITRL, also known as TNFSF18 and AITRL, along with its corresponding receptor, are members of the TNF superfamily. GITRL is expressed in endothelial cells and is thought to modulate T lymphocyte survival in peripheral tissues. It plays a role in interactions between activated T lymphocytes and endothelial cells. GITRL also triggers an increase in the capability of endothelial cells to support leukocyte adhesion.