Description: This 26F8 monoclonal antibody reacts with human CD317 (also known as BST2 and tetherin). CD317 is a 30-36-kDa type II transmembrane protein expressed on B cells and bone marrow stromal cells. Although reports have indicated that CD317 mRNA is detectable in activated T cells, protein expression in primary T cells and macrophages is undetectable. Moreover, certain T cell lines, such as Jurkat, do not express detectable levels of CD317 protein. CD317 has been associated with pre-B cell growth and the terminal differentiation of plasma B cells. More recently, this molecule has been reported to prevent HIV-1 virion release from the surface of infected cells, leading to reuptake and degradation of the virus. This activity is inhibited by the HIV-1 accessory protein Vpu. CD317 has been identified as the ligand for the ILT7 receptor.