The SY/11B5 monoclonal antibody specifically binds to CD157 which is also known as BST-1 (Bone marrow stromal antigen 1), BP-3/IF-7, Mo5, ADP-ribosyl cyclase 2, and cADPr hydrolase 2. CD157 is a 40-46 kDa glycophosphatidylinositol-linked cell membrane glycoprotein. It is an ectoenzyme that has both cyclic ADP-ribose hydrolase and ADP-ribosyl cyclase activities. CD157 is expressed as a homodimer by a variety of cell types including bone marrow stromal cells, granulocytes, monocytes, macrophages, dendritic cells, endothelial cells, and B and T cell progenitors. In addition to its ectoenzyme activities, CD157 reportedly functions as a receptor involved in neutrophil and monocyte adhesion, transendothelial migration and diapedesis and in tumor cell migration.
The antibody was conjugated to BD Horizon™ BUV661 which is part of the BD Horizon Brilliant™ Ultraviolet family of dyes. This dye is a tandem fluorochrome of BD Horizon BUV395 with an Ex Max of 348-nm and an acceptor dye with an Em Max at 661-nm. BD Horizon Brilliant BUV661 can be excited by the ultraviolet laser (355 nm) and detected with a 670/25 filter and a 630 nm LP. Due to cross laser excitation of this dye, there may be significant spillover into channels detecting APC-like emissions (eg, 670/25-nm filter).
Due to spectral differences between labeled cells and beads, using BD™ CompBeads can result in incorrect spillover values when used with BD Horizon BUV661 reagents. Therefore, the use of BD CompBeads or BD CompBeads Plus to determine spillover values for these reagents is not recommended. Different BUV661 reagents (eg, CD4 vs. CD45) can have slightly different fluorescence spillover therefore, it may also be necessary to use clone-specific compensation controls when using these reagents.