The 657909 monoclonal antibody specifically recognizes Tetraspanin-8 (TSPAN8) that belongs to the Transmembrane 4 (Tetraspanin) superfamily (TM4SF). This molecule is also known as Transmembrane 4 superfamily member 3 (TM4SF3). TSPAN8 is a protein that spans the membrane four times with transmembrane segments and has intracellular N- and C-termini. TSPAN8 has a small and a large extracellular loop that can mediate dimerization and association with other molecules including integrins, proteases, or cell signaling receptors. TSPAN8 is variably expressed on hematopoietic progenitor cells, spermatogonial stem cells, epithelial cells, and some tumor cells. TSPAN8 is involved in epithelial wound healing and may contribute to tumor cell metastasis.
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.