Clone DX9 recognizes CD158e (KIR3DL1), a member of the killer immunoglobulin-like receptor (KIR) family expressed on CD56dimCD16+ natural killer (NK) cells and CD8+ T cells. KIRs contribute to the regulation of NK cell-mediated cytotoxicity. They are monomeric receptors possessing high allelic polymorphism with either 2 or 3 Ig-like extracellular domains. According to the length of their cytoplasmic tail, KIRs can be further subdivided into inhibitory KIRs and activating KIRs (KIR2DS or KIR3DS). KIR3DL1 provides an inhibitory signal of NK cell lytic activity upon interaction with its specific ligand, HLA-Bw4.
Human peripheral blood mononuclear cells (PBMCs) were stained with CD158e (KIR3DL1) antibodies as well as with CD56 antibodies and analyzed by flow cytometry using the MACSQuant® Analyzer. The Tandem Signal Enhancer has been used to increase binding specificity of tandem-dye–conjugated antibodies. Cell debris and dead cells were excluded from the analysis based on scatter signals and propidium iodide fluorescence or 4',6-diamidino-2-phenylindole (DAPI) fluorescence, as in the case of tandems.