The DX9 monoclonal antibody specifically binds to CD158e1, also known as NKB1. CD158e1 functions as a killer cell inhibitory receptor (KIR) and is encoded by KIR3DL1 (Killer cell immunoglobulin-like receptor, three domains, long cytoplasmic tail). CD158e1 is a 70 kDa glycoprotein that belongs to the Ig superfamily. It is expressed on a subset of natural killer cells and a small subset of T cells. Expression of CD158e1 has been observed to vary among individuals. KIR molecules specifically recognize a certain group of HLA class I antigens. Interaction of CD158e1 with specific HLA-B antigen on a target cell appears to inhibit cell-mediated cytotoxicity by delivering a negative signal that prevents lymphocyte activation. It is suggested that this MHC class I-KIR interaction works as a signaling mechanism that regulates NK and T-cell responses to antigenic challenge.
The antibody was conjugated to BD Horizon BV750 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 750-nm. BD Horizon Brilliant BV750 can be excited by the violet laser (405 nm) and detected with a 750/30 nm filter with a 740 nm long pass. Due to spectral differences between labeled cells and beads, using BD™ CompBeads can result in incorrect spillover values when used with BD Horizon BV750 reagents. Therefore, the use of BD CompBeads or BD CompBeads Plus to determine spillover values for these reagents is not recommended.