Leukocyte Immunoglobulin-Like Receptor B4 (LILRB4)

Leukocyte immunoglobulin-like receptor B member 4 (LILRB4), also known as ILT3, LIR-5, and CD85k, is a type I transmembrane glycoprotein that functions as an inhibitory immune receptor. It is primarily expressed on monocytes, macrophages, dendritic cells (especially tolerogenic DCs), vascular endothelial cells, tumor-associated macrophages, and monocytic myeloid leukemia cells. Upon ligand binding, its ITIM motifs recruit phosphatases such as SHP‐1/SHIP‐1, leading to inhibition of activating signaling pathways within immune cells, ultimately promoting immune tolerance. It has emerged as a potential target for cancer immunotherapy, and a soluble isoform circulating in cancer patient serum may serve as a biomarker.

Other names

ILT3LIR-5CD85k

Inhibition of activating signaling pathways via recruitment of SHP-1/PTPN6 and SHIP-1/INPP5D phosphatases to ITIM motifs.