Recombinant Human 4-1BBL

4-1BB ligand (4-1BBL), also known as TNFSF9 and CD137L, is a type 2 transmembrane glycoprotein belonging to the TNF superfamily. It is a ligand for TNFRSF9, which is a co-stimulatory molecule in T lymphocytes. 4-1BBL and its receptor are involved in the antigen presentation process, generation of cytotoxic T cells and are required for the optimal CD8 responses in CD8 T cells (1). It is expressed on activated T and B cells, macrophages, dendritic cells, neurons and astrocytes (2-3). 4-1BBL also plays an important role in co-stimulation of IL-2 production (3). In addition, 4-1BBL is expressed in various carcinoma cell lines, and is thought to be involved in T cell-tumor cell interaction (4). One study reports the long-term remission of liver metastases in a mouse model involving the gene transfer of IL-12 and 4-1BBL (5).