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™ BV711 which is part of the BD Horizon Brilliant™ Violet family of dyes. This dye is a tandem fluorochrome of BD Horizon BV421 with an Ex Max of 405-nm and an acceptor dye with an Em Max at 711-nm. BD Horizon BV711 can be excited by the violet laser and detected in a filter used to detect Cy™5.5 / Alexa Fluor™ 700-like dyes (eg, 712/20-nm filter). Due to the excitation and emission characteristics of the acceptor dye, there may be moderate spillover into the Alexa Fluor™ 700 and PerCP-Cy5.5 detectors. However, the spillover can be corrected through compensation as with any other dye combination.