The LILRs are a family of receptors that regulate the activities of myelomonocytic cells. LILRB3 and LILRA6 represent a pair of inhibitory/activating receptors with identical extracellular domains and unknown ligands. LILRB3 (ILT5) and LILRA6 (ILT8) are highly polymorphic receptors with similar extracellular domains. LILRA6 can signal through association with an activating adaptor molecule, FcR¦Ã, which bears a cytoplasmic tail with an immunoreceptor tyrosine-based activation motif. Analysis of mRNA expression in the major fractions of PBMCs showed that LILRA6 is primarily expressed in monocytes, and its expression level correlates with copy number of the gene.