Immunoglobulin-Like Transcript 5, Recombinant, Human (ILT5, CD85a, CD85 antigen-like family member A

Immunoglobulin-like transcript 5 (ILT5), also known as leukocyte immunoglobulin-like receptor subfamily B (LILRB3), leukocyte immunoglobulin-like receptor 3 (LI R3) and CD85a, is an Ig-like recept or family member that is involved in immune regulation. ILT5 belongs to subfamily B whose members have cytoplasmic tails that contain immunoreceptor tyrosine-based inhibitory motifs (ITIMs) that inhibit signaling events via phosphatase SHP-1. The counterpart to subfamily B is subfamily A, whose members qualify as activating receptors that lack ITIMs, but signal through association with FcRg . ILTs share structural homology and chromosomal localization with the KIR family of receptors (1, 2). Mature ILT5 is a highly polymorphic 85-95kD glycoprotein that consists of a 420aa extracellular domain with four Ig-like domains, a 21aa transmembrane segment, and a 167aa cytoplasmic domain with three ITIMs (3, 4). Alternate splicing generates an isoform with a 17aa insertion in the juxtamembrane ECD. In mouse and rat , the LILRB3 gene encodes the PIR­B protein which has six Ig­like domains. Rodent PIR­B and human ILT5 share 55% aa sequence identity within common regions of thei rECDs. Both PIR­B and ILT5 are receptors for S. aureus, and activation of these receptors by bacteria influences the innate immune response triggered by TLRs (4). ILT5 is expressed on the surface of peripheral monocytes, neutrophils, eosinophils, basophils, and mast cell progenitors but not on mature mast cells (5­7). On basophils, cross­linking of ILT5 to the activating receptors ILT1/LIR7 or FceRI inhibits the release of histamine, leukotriene C4, and IL­4 (6). On osteoclast precursors, ILT5 ligation inhibits RANKL or M­CSF induced differentiation (8). ILT5 is downregulated on macrophages in rheumatoid arthritis synovial ti ssue following successful treatment with DMARD anti­rheumatic drugs (9). A DNA sequence encoding human Immunoglobulin-Like Transcript 5 (Gly24-Glu443, Accession #AAB68668) fused to IEGRMD and human IgG1 (Pro100-Lys330) at the C-terminus expressed in NSO cells. , SDS-PAGE: 95-105kD, reducing conditions. Biological Activity: Measured by its ability to bind fluorescein-conjugated S. aureus Bioparticles. The ED50 for this effect is typically 0.4-2ug/ml, Storage and Stability: Lyophilized powder may be stored at -20°C. Stable for 12 months at -20°C. Reconstitute with sterile PBS. Aliquot to avoid repeated freezing and thawing. Store at -20°C. Reconstituted product is stable for 6 months at -20°C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.