The CW-1.2 monoclonal antibody specifically binds to CD199 which is also known as Chemokine (C-C motif) receptor 9 (CCR9) or C-C chemokine receptor type 9 (C-C CKR-9). CD199 is a ~42 kDa seven-transmembrane protein and member of the G protein-coupled receptor 1 family. CD199 binds to CCL25, which is likewise known as thymus-expressed chemokine (TECK) or small inducible chemokine 25 (Scya25). CCL25 is selectively and constitutively expressed in the thymic cortex and small intestinal epithelium. CD199 is highly expressed on CD4+CD8+ double-positive thymocytes, and mature naïve CD8+ T cells, but not naïve CD4+ T cells, in the peripheral lymphoid organs. CD199 is also expressed on small intestinal B cells, and on subsets of memory CD4+ T cells and CD8+ T cells, and dendritic cells. The CCR9/CCL25 pathway plays important roles in T cell development and gut-associated immune functions. It is especially involved in the recruitment of CD8αα+ intraepithelial lymphocytes (IELs) and the homing of other lymphocytes to the gut. Dysregulation of this pathway is associated with inflammatory responses, such as inflammatory bowel disease (IBD) and celiac disease.
The antibody was conjugated to BD Horizon BB515 which is part of the BD Horizon Brilliant™ Blue family of dyes. With an Ex Max near 490 nm and an Em Max near 515 nm, BD Horizon BB515 can be excited by the blue laser (488 nm) laser and detected with a 530/30 nm filter. This dye has been exclusively developed by BD Biosciences and is up to seven times brighter than FITC with less spillover into the PE channel. Due to similar excitation and emission properties, BB515, FITC, and Alexa Fluor® 488 cannot be used simultaneously. It is not recommended to use BB515 in cocktails that include Streptavidin conjugates as it may cause high background.