Signaling lymphocyte activation molecule (SLAM), is a self-ligand glycoprotein which exists not only found on the surface of activated and memory T cells, but also on the surface of activated B cells, dendritic cells, and macrophages. SLAM consists of a extracellular domain (ECD) with two Ig-like domains,transmembrane segment, and cytoplasmic domain with three immunoreceptor tyrosine switch motifs (ITSM). SLAM is thought to play an important role in adhesion between T cells and APCs and has been shown to act as a coreceptor in TCR-dependent responses. SLAM, together with CD46, is one of the two receptors for measles virus. SLAM is a cell surface receptor that, like the B cell receptor, CD40, and CD95, can transmit positive or negative signals. SLAM can associate with the SH2-containing inositol phosphatase (SHIP), the SH2-containing protein tyrosine phosphatase (SHP-2), and the adaptor protein SH2 domain protein 1A. It’s upregulated on activated B cells and CD4+ and CD8+ T cells, but downregulated on Th2 polarized cells. Also, it can Inhibits antigen receptor-mediated production of IFN-gamma, but not IL-2, in CD4-/CD8- T-cells