AITRL also known as TNFSF18, GITRL and TL6, belonging to TNF superfamily. AITRL is a 20.3 kDa protein containing 177 residues that implicates in regulating immune systems. AITRL contributes to tumor suppression and the development of autoimmune diseases via interacting with TNFRSF18/AITR/GITR. Besides, AITRL-GITR signaling has been demonstrated to enhance phosphorylation of STAT1 and up-regulate expression of VCAM1 and ICAM1 in endothelial cells. Furthermore, AITRL can also facilitate the adhesion and transmigration of leukocytes to endothelial cells.