LILRA6

LILRA6 (leukocyte immunoglobulin-like receptor A6, also CD85B/LIR-9) is an activating LILR family member located in the leukocyte receptor complex, structurally related to inhibitory LILRB1 but distinguished by its short cytoplasmic tail lacking ITIMs and by a charged transmembrane residue that associates with the FcRγ chain (FcεRIγ) or DAP12 adaptors for activating SYK-dependent signal transduction. LILRA6 is expressed on myeloid cells-monocytes, macrophages, neutrophils and dendritic cells-and at low levels on NK and B cell subsets. Its extracellular D1-D2 Ig domains share close homology with LILRB1, and LILRA6 binds selected HLA class I molecules including HLA-B and HLA-G allotypes, but with weaker affinity than its inhibitory counterpart, consistent with a paired receptor system in which activation and inhibition are calibrated by ligand density and cellular context. Genetic LILRA6 variants and copy-number polymorphisms influence receptor expression and function; LILRA6 has been associated with susceptibility to infectious and inflammatory diseases, and enhanced myeloid activation phenotypes including cytokine production and antitumor responses in experimental systems.