The U21-1283 monoclonal antibody specifically recognizes Neuropilin-1 (NRP1), also known as CD304, Blood dendritic cell antigen 4 (BDCA4), and Vascular endothelial cell growth factor 165 receptor (VEGF165R). CD304 is a type I transmembrane glycoprotein involved in the development of the nervous and cardiovascular systems. It mediates the interaction, growth, survival, and migration of a variety of normal and tumor cells. CD304 is expressed on neurons, thymocytes, regulatory T cells, a subset of T follicular helper cells, dendritic cells, endothelial cells, and certain tumor cells. Neuropilin-1 has a very short cytoplasmic domain and interacts with various coreceptors to form ligand-binding, signal-transducing receptor complexes. CD304 complexes with Plexin-A family members to bind chemorepellent Class 3 Semaphorins and guide neuronal axon growth. It also functions as a coreceptor with VEGFR2/CD309 to stimulate angiogenesis in response to VEGF165. CD304 mediates the interactions between some T cells and dendritic cells.
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.