The C9Mab-1 monoclonal antibody specifically binds to Chemokine (C-C motif) receptor 9 (CCR9), which is also known as CD199. CCR9 is an ~42 kDa seven-transmembrane protein in the G protein-coupled receptor (GPCR) supergene family. It is upregulated by CD4+CD8+ double-positive thymocytes, then downregulated in committed CD4+ or CD8+ single-positive thymocytes. CCR9 is also expressed on small intestinal B cells, subsets of memory CD4+ T cells and CD8+ T cells, and dendritic cells. CCR9 binds CCL25, which is also known as thymus-expressed chemokine (TECK) or small inducible chemokine 25 (Scya25). CCL25 is highly expressed in the thymic cortex and small intestinal epithelium. CCR9 is involved in T cell development and gut-associated immune functions via lymphocyte recruitment to the gastrointestinal tract.
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).