Alexa Fluor^® 647 Mouse Anti-Human CD158b/j Antibody (S-2917)

CD158b/j, also known as Killer Cell Immunoglobulin-Like Receptor 2DL2/3 (KIR2DL2/3), is a highly polymorphic inhibitory receptor belonging to the KIR family that is primarily expressed on the surface of natural killer (NK) cells and specific T-cell subsets, where it plays a critical role in regulating immune responses by recognizing specific epitopes of Human Leukocyte Antigen (HLA)-C group 1 molecules (characterized by an asparagine at position 80). Structurally, this type I transmembrane glycoprotein features two extracellular immunoglobulin-like domains, a transmembrane region, and a long cytoplasmic tail containing immunoreceptor tyrosine-based inhibitory motifs (ITIMs); upon binding to its HLA-C ligand on healthy self-cells, these ITIMs become phosphorylated and recruit phosphatases such as SHP-1 or SHP-2 to dampen downstream activating signaling cascades, thereby preventing NK cell-mediated cytotoxicity and cytokine release against normal tissues. The "b/j" designation reflects the complex genetic variation and serological cross-reactivity often observed between the KIR2DL2 and KIR2DL3 gene products, which share significant sequence homology but differ in their binding avidity and functional thresholds, making CD158b/j a pivotal checkpoint in maintaining self-tolerance, shaping NK cell education, and influencing clinical outcomes in scenarios such as viral infections, pregnancy complications, and hematopoietic stem cell transplantation where donor-recipient KIR-HLA mismatches can significantly alter graft-versus-leukemia effects or graft rejection risks.