LILRB4/CD85k (F2W8T) Rabbit mAb #93591

The leukocyte Ig-like receptor subfamily B (LILRB) are type-I transmembrane glycoproteins containing ligand-binding extracellular IgG-like domains and immunoreceptor tyrosine-based inhibition motifs (ITIMS) within the cytoplasmic domain, which recruit SHP protein tyrosine phosphatases, leading to transduction of signals that inhibit immune cell activation. Encoded within a region of chromosome 19 known as the leukocyte receptor complex, the LILRB subfamily of inhibitory receptors consists of LILRB1 to LILRB5, also referred to as CD85J, CD85D, CD85A, CD85K, and CD85C, respectively (1). There is mounting evidence that LILRBs function, in part, as a novel class of immune checkpoint receptors and support tumor growth through the transmission of inhibitory signals upon engagement of ligands expressed on tumor cells (2).

LILRB4 is expressed on various immune cell types, such as monocytes, macrophages, dendritic cells (DCs), mast cells, B cells, T cells, and natural killer (NK) cells (3,4). LILRB4 expression is elevated in leukemia cells and promotes an immunosuppressive microenvironment by inhibiting T cell activity (5). LILRB4 expression is also associated with multiple myeloma (MM), and knockdown of LILRB4 has been shown to restrict MM cell proliferation (6,7). Knockout of LILRB4 or treatment with an anti-LILRB4 antibody has also been shown to reduce tumor burden in various murine tumor models, further suggesting that LILRB4 can be targeted for immunotherapies (8).