• Purity

  >95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.

• Endotoxin Level

  <0.10 EU per 1 μg of the protein by the LAL method.  

• Activity

  Measured by its binding ability in a functional ELISA. When Recombinant Human LILRB4/CD85k/ILT3 is coated at 2 μg/mL, Recombinant Human Angiopoietin-like Protein 7/ANGPTL7 (Catalog # ) binds with an apparent K    _d <1 nM.  

• Source

  Mouse myeloma cell line, NS0-derived Pro17-His257, with a C-terminal 6-His tag

• Accession #

• N-terminal Sequence    
  Analysis

  Pro17& Ala (N+3 of signal derived sequence)

• Predicted Molecular Mass

  27 kDa

• SDS-PAGE

  29-43 kDa, reducing conditions

Background: LILRB4/CD85k/ILT3

ILT3, also known as CD85k and LIR-5, is an approximately 60 kDa transmembrane glycoprotein that negatively regulates immune cell activation (1). Mature human ILT3 consists of a 238 amino acid (aa) extracellular domain with two Ig-like domains, a 21 aa transmembrane segment, and a 168 aa cytoplasmic domain with 3 immunoreceptor tyrosine-based inhibitory motifs (ITIM) (2). Alternative splicing of human ILT3 generates an isoform that lacks the first ITIM and a secreted isoform that circulates in the serum of cancer patients (3, 4). ILT3 is expressed on dendritic cells (DC), monocytes, macrophages, and vascular endothelial cells (EC) (2, 5, 6). Ligation of ILT3 triggers ITIM-mediated inhibition of cell-activating signaling, leading to enhanced immune tolerance and reduced allogeneic graft rejection (2, 4, 7, 8). Soluble ILT3 induces the differentiation of CD8  ⁺ T suppressor cells (Ts) that can inhibit the effector functions of CD4  ⁺ Th cells and CD8  ⁺ CTL (4, 7, 9). In turn, CD8  ⁺ Ts cells induce ILT3 up-regulation and a tolerogenic phenotype in monocytes, DC, and EC (5, 6, 8, 10, 11).

• References:

1. Vlad, G. et al. (2010) Int. Rev. Immunol. 29:119.

2. Cella, M. et al. (1997) J. Exp. Med. 185:1743.

3. Heinzmann, A. et al. (2000) Eur. J. Immunogenet. 27:121.

4. Suciu-Foca, N. et al. (2007) J. Immunol. 178:7432.

5. Gleissner, C.A. et al. (2007) Eur. J. Immunol. 37:177.

6. Manavalan, J.S. et al. (2004) Int. Immunol. 16:1055.

7. Vlad, G. and N. Suciu-Foca (2012) Exp. Mol. Pathol. 93:294.

8. Chang, C.C. et al. (2002) Nat. Immunol. 3:237.

9. Vlad, G. et al. (2006) Int. Immunopharmacol. 6:1889.

10. Manavalan, J.S. et al. (2003) Transpl. Immunol. 11:245.

11. Brenk, M. et al. (2009) J. Immunol. 183:145.

• Long Name:

  Leukocyte Immunoglobulin-like Receptor, Subfamily B (with TM and ITIM Domains), Member 4

• Entrez Gene IDs:

  11006 (Human); 14728 (Mouse)

• Alternate Names:

  CD85 antigen-like family member K; CD85k antigen; CD85k; HM18; ILT3; ILT-3; ILT3CD85K; leukocyte immunoglobulin-like receptor, subfamily B (with TM and ITIM domains); LILRB4; LIR5; LIR5LILRB5; LIR-5subfamily B, member 4; member 4