LILRB1, also known as CD85j and ILT2, is a transmembrane immunoregulatory protein that is expressed on the surface of B cells and monocytes, as well as subsets of NK cells, memory/effector CD8+ T cells, gamma/delta T cells, and monocyte-derived dendritic cells. LILRB1 binds to MHC-I as well as non-classical MHC-I molecules (e.g. HLA-F, HLA-G, and HC-B27), the MHC-I mimetic UL18 encoded by cytomegalovirus, and Angiopoietin-like 7. Ligation of LILRB1 inhibits the antigen induced proliferation and activation of CD8+ T cells, CD4+ T cells, NK cells, and gamma/delta T cells. On dendritic cells, ligation inhibits the production of IL-10, IL-12p70, and TGF-beta and protects from Fas-mediated apoptosis.