Leukocyte Ig-like receptors (LIRs) are a family of immunoreceptors expressed predominantly on monocytes and B cells and at lower levels on dendritic cells and natural killer (NK) cells. All LIRs in subfamily B have an inhibitory function . LIRs in subfamily A, with short cytoplasmic domains lacking an immunoreceptor tyrosine-based inhibitory motif (ITIM) and with transmembrane regions containing a charged arginine residue, may initiate stimulatory cascades .
Acts as soluble receptor for class I MHC antigens. Binds both classical and non-classical HLA class I molecules but with reduced affinities compared to LILRB1 or LILRB2. Binds with high affinity to the surface of monocytes, leading to abolish LPS-induced TNF-alpha production by monocytes.