Leukocyte immunoglobulin-like receptor B1 (LILRB1), Leukocyte immunoglobulin-like receptor B2 (LILRB2), Leukocyte immunoglobulin-like receptor B3 (LILRB3) (LILRB1, LILRB2, LILRB3)

Leukocyte immunoglobulin-like receptors B1, B2, and B3 are part of the immunoglobulin superfamily and are expressed mainly on myeloid cells (monocytes, macrophages, dendritic cells), as well as subsets of B cells, T cells, and NK cells. These receptors bind to classical and non-classical MHC class I proteins, including HLA-G, to deliver inhibitory signals that dampen immune cell activation, help maintain tolerance to self, and regulate inflammation. In cancer, especially multiple myeloma, these receptors promote immune escape and tumor survival, and are considered promising targets for novel immunotherapies. LILRB1/B2/B3 engagement controls innate and adaptive immunity, impacts antigen presentation, and modulates cell proliferation and cytokine secretion. Their dysfunction or aberrant expression is implicated in cancer, autoimmune diseases, transplant biology, and infectious diseases.

Other names

CD85j (LILRB1)CD85d (LILRB2)ILT2 (LILRB1)ILT4 (LILRB2)ILT5 (LILRB3)Immunoglobulin-like transcript 2/4/5 (ILT2/ILT4/ILT5)Monocyte/macrophage antigen (sometimes used generically)

Immune checkpoint inhibition (antibody blockade to restore T cell/NK/cytotoxic function) Disruption of ligand binding (to MHC class I/β2-microglobulin, HLA-G) to prevent immunosuppressive signaling