[摘要] 淋巴细胞活化基因3（lymphocyte-activation gene 3，LAG-3）又称CD223，是一种由LAG-3 基因编码的含有498 个氨基酸的I 型穿膜蛋白，由胞外区、穿膜区和胞内区三部分组成。LAG-3 主要通过胞外区与配体结合，负向调控T淋巴细胞，避免T细胞过度激活引发自身免疫。与程序性死亡蛋白-1（programmed cell death 1，PD-1）和细胞毒性T淋巴细胞抗原4（cytotoxic T lymphocyte antigen 4，CTLA-4）一样，LAG-3 是体内重要的免疫检查点，对人体免疫系统起到平衡调控作用。肿瘤细胞通过高表达LAG-3 配体逃避机体免疫系统的监视。随着免疫检查点的研究逐渐深入，LAG-3 成为继PD-1 和CTLA-4 之后新一代的免疫治疗靶点。本文主要对LAG-3的结构、功能及其抑制剂在肿瘤免疫治疗中的应用进行综述，以期为LAG-3 的进一步研究提供参考。

[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.

国家自然科学基金资助项目（No.31470897，81602457）;海军总医院创新培育基金资助项目（No.CXPY201817）