May act as receptor (By similarity). Negatively regulates TCR-mediated CD4(+) T cell proliferation and activation, possibly by binding an unknown ligand on the T cell surface (PubMed:26311901). Enhances Toll-like receptor-mediated production of pro-inflammatory cytokines by macrophages and neutrophils (By similarity). Interacts with Fc receptor gamma chain FCER1G. Expressed in fetal and adult liver, lung, testis, thymus and spleen. Expressed in blood neutrophils. N-glycosylated.