ABSTRACT
@# Lymphocyte-activation gene 3 (LAG-3), also known as CD223, is a 498-amino-acid type I transmembrane protein encoded by LAG-3 gene, which consists of extracellular, transmembrane and intracellular regions.LAG-3 negatively regulates T lymphocyte by binding extracellular domain to ligand, thus avoiding autoimmunitycaused by T cell over-activation. Like programmed cell death 1 (PD-1) and cytotoxic T lymphocyte antigen 4 (CTLA-4), LAG-3 is an important immune checkpoint in vivo and plays a balanced regulatory role in human immune system.Tumor cells escape the surveillance of the immune system by over-expressing LAG-3 ligand. With the development in research of immune checkpoints, LAG-3 has become a new generation of immunotherapy targets after PD-1 and CTLA-4. This article reviews the structure and function of LAG-3 and the application of its inhibitors in tumor immunotherapy, in order to provide reference for the further study of LAG-3.