Lysosomal associated membrane protein 1 (LAMP-1), also known as CD107a and LGP120, is an approximately 120 kDa transmembrane glycoprotein that is a major protein component of lysosomal membranes. In cytotoxic T cells and mast cells, LAMP-1 is expressed in the membranes of intracellular granules that contain effector molecules such as perforin, granzymes, eicosanoids, and histamine. LAMP-1 is presented on the plasma membrane during the activation of NK cells, CD8+ T cells, mast cells, basophils, monocytes, and platelets. A glycoform of LAMP-1 known as M150 is expressed on the
surface of activated macrophages where it promotes T cell costimulation and a Th1 biased immune response.