Mouse SLAM family member 8/SLAMF8 is a single-pass type I membrane protein. It contains one Ig-likeC2-type domain. SLAMF8 is expressed in lymphnode, spleen, thymus and bone marrow. The signaling lymphocyte activation molecule (SLAM) family includes homophilic and heterophilic receptors that modulate both adaptive and innate immune responses. These receptors share a common ectodomain organization: a membrane-proximal immunoglobulin constant domain and a membrane-distal immunoglobulin variable domain that is responsible for ligand recognition. SLAM family of receptors is expressed by a wide range of immune cells. Through their cytoplasmic domain, SLAM family receptors associate with SLAM-associated protein (SAP)-related molecules, a group of cytoplasmic adaptors composed almost exclusively of an SRC homology 2 domain. SLAM family receptors, inassociation with SAP family adaptors, have crucial roles during normal immune reactions in innate and adaptive immune cells. It may play a role in B-lineage commitment and/or modulation of signaling through the B-cell receptor.