The A8 monoclonal antibody specifically binds to CD100 which is also known as Semaphorin-4D (SEMA4D). CD100 is a 150 kDa type I transmembrane glycoprotein that belongs to the semaphorin family. CD100 is widely expressed in the nervous and immune systems. Although it is expressed on T cells, its expression is significantly upregulated on activated T cells. It is also expressed on NK cells, B cells, and monocytes. CD100 is an adhesion molecule that functions as a signaling molecule which plays a role in lymphocyte activation. CD100 interaction with CD72 enhances B cell signaling and ultimately promotes B cell activation and survival.
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.