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 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).