General Notes
Mouse anti Human CD137, clone 4B4-1 recognizes CD137. CD137 (also known as 4-1BB ligand receptor or TNFRSF9) is a type I transmembrane glycoprotein of the Tumor Necrosis Factor receptor family that is expressed on activated T and NK cells, dendritic cells, myeloid cells and at the surface of some non-lymphoid cells under specific conditions (Schwarz et al. 1995). CD137 acts as a receptor for 4-1BB ligand, expressed on activated macrophages, activated B cells, hematopoietic stem cells and myeloid progenitor cells (Pollock et al. 1994) and for some proteins of the extracellular matrix (Chalupny et al. 1992).The interaction between CD137 and 4-1BBL acts as a co-stimulatory signal for the activation, expansion and survival of T cells (Wen et al. 2002). CD137 signaling is involved in the generation of CD8+ T cells and enhance their cytotoxic activity (Shuford et al. 1997). Because of its ability to promote the anti-tumorigenic activity of cytotoxic T cells, CD137 is the target of several cancer immune therapies, such as the agonist anti-CD137 Urelumab (Segal et al. 2017) and Utomilumab (Chester et al. 2018). CD137 also binds to the adaptor proteins TRAF1, 2 and 3 to promote NF-kappaB activation (Jang et al. 1998).Mouse anti-human CD137, clone 4B4-1 has been reported to immunoprecipitate a homodimeric protein of 32kDa under reducing conditions and 85kDa under non-reducing conditions (Garni-Wagner et al. 1996).