Mouse GITR Ligand/TNFSF18 Antibody

Glucocorticoid-induced TNF receptor superfamily-related protein ligand (GITRL) is a member of the TNF superfamily (TNFSF) and has been designated TNFSF18. Mouse GITRL cDNA encodes a 173 amino acid (aa) type II membrane protein with a C-terminal extracellular domain of 131 aa, an N-terminal cytoplasmic domain of 23 aa and a transmembrane domain of 19 aa. It shares approximately 60% aa sequence identity with human GITRL (2). Mouse GITRL is expressed at high levels in macrophages, dendritic cells and B cells. The expression is transiently upregulated by LPS stimulation. GITRL binds to the type I transmembrane protein GITR/TNFRSF18, which is a member of the TNF receptor superfamily that is predominantly expressed on CD25⁺ regulatory CD4⁺ T cells (Treg). GITR is also expressed on naïve CD4⁺ CD25^- T cells, where its expression is upregulated after antigen-driven activation (1, 2). Ligation of GITR has been found to induce nuclear factor (NF)-kappa B activation via TNF receptor-associated factor 2. GITRL provides costimulatory signals for activated CD4⁺ CD25^- T cells to enhance cell proliferation and augment cytokine production. On CD4⁺ CD25⁺ Treg cells, GITRL also provides costimulatory signals to induce proliferation, setting Treg cells in an active/hyperproliferactive state that reverses the suppressive function of Treg cells. GITRL-GITR ligation provides important costimulatory signals that play important roles in modulating diverse T cell functions (1-4).