Triggering receptor expressed on myeloid cells-2 (TREM-2) is a cell surface receptor primarily expressed on macrophages, osteoclasts, microglia and dendritic cells. TREM-2 is one member of the TREM family, inhibiting the releasing of inflammatory mediators, so it is an important in vivo anti-inflammatory receptor. TREM-2 consists of an 18 aa signal sequence, a 153 aa extracellular domain (ECD) with one V-type Ig-like domain, a 21 aa transmembrane (TM) domain, and a 35 aa cytoplasmic tail. A soluble form of TREM-2 (TREM-2b) created by alternate splicing diverges at aa 161. TREM-2 transduces intracellular signals through the adaptor DAP12. After binding of TREM-2 with ligand, the TREM-2/DAP12 (dead-cell-activated-receptor-associated protein)-mediated signal transduction pathway causes a series of intracellular protein tyrosine phosphorylation reactions and enzymatic reactions, which then activate the myeloid cells and participate T cell responses.