Triggering receptor expressed on myeloid cell-like transcript 2 (TLT-2, TREML2) is a type I transmembrane protein in TREM family. It consists of a single extracellular Ig-like domain of the V-type, a transmembrane domain, and a short cytoplasmic domain. TLT-2 is expressed on myeloid , B cells , and macrophages. It was also found to express on CD8+ T cells and activated CD4+ T cells. It regulates innate immune response based on its expression profile, costimulates the activation of T cells. Transduction of TLT-2 into T cells resulted in enhanced IL-2 and IFN-gamma production. It was reported that B3-H7 is a receptor of TLT-2. Blockade of the B7-H3/ TLT-2 pathway with monoclonal antibodies against B7-H3 or TLT-2 efficiently inhibited hypersensitivity response. Further studies are needed to confirm the ligand.