Mouse 4-1BB/TNFRSF9/CD137 Antibody

4-1BB, also known as CD137 and ILA (induced by lymphocyte activation), is a TNF receptor superfamily member and has been designated TNFRSF9. Mouse 4‑1BB cDNA encodes a 256 amino acid (aa) residues type I transmembrane protein with a putative 23 aa signal peptide, a 164 aa extracellular domain, a 21 aa transmembrane domain and a 48 aa cytoplasmic region (1‑3). A soluble 4‑1BB is released from surfaces of cells expressing the transmembrane protein (4).
Mouse 4‑1BB shares approximately 60% aa sequence identity with its human counterpart. 4‑1BB is expressed on activated CD4⁺ and CD8⁺ T cells, thymocytes, and NK cells. It is also expressed on monocytes, neutrophils, DCs and eosinophils (5). The ligand for 4‑1BB (4‑1BBL), also named TNFSF9, belongs to the TNF ligand superfamily. 4‑1BBL is predominantly expressed on activated antigen presenting cells (APCs) such as B cells, macrophages and dendritic cells (DCs). It is also expressed on most T and B lymphoma cell lines. In response to 4‑1BBL binding, 4‑1BB transduce a T cell costimulatory signal in both CD4⁺ and CD8⁺ T cells to promote survival and enhance proliferation, cytokine production and effector function. In vivo, the costimulatory activity of 4‑1BB has been shown to be important in graft-vs-host disease and antiviral CTL responses. On dendritic cells, 4‑1BB is a DC-activating molecules that enhances cytokine production and up‑regulates expression of B7-1 and B7-2 costimulatory molecules, resulting in an improved ability to stimulate T cell responses (1‑5).