Lymphocyte activation gene 3 protein (LAG3) is also known as CD antigen CD223 and protein FDC. It belongs to immunoglobulin (Ig) superfamily and contains 4 extracellular Ig-like domains. LAG3/CD223 is one of the inhibitory receptors by negatively regulating cellular proliferation, activation, and homeostasis of T cells. LAG3 can bind to HLA class-II antigens and is involved in lymphocyte activation and autoimmunity. There are now LAG3 targeted therapies both in the clinic and in preclinical development, emphasizing the broad interest in this inhibitory receptor. MW: 47 kDa. Purity ≥95%