综述:髓系衍生的抑制性细胞与肿瘤免疫耐受关系的研究进展

髓系衍生的抑制性细胞(myeloid-derived suppressor cells,MDSCs),是在肿瘤等病理因素的作用下髓系细胞发生分化障碍所产生的不同阶段髓系祖细胞的集合,具有广谱而强大的免疫抑制功能,是免疫系统的重要负性调节组件之一.研究表明:肿瘤微环境中的多种细胞因子或生长因子可通过激活相应的信号通路促进MDSCs扩增及活化,MDSCs进而通过多种机制抑制包括T细胞在内的多种免疫细胞的功能而促进肿瘤个体免疫耐受的发生.临床研究表明:肿瘤患者体内MDSCs的水平与肿瘤临床病程进展密切相关,基于MDSCs的免疫治疗也有望成为肿瘤免疫治疗的新策略.本文主要介绍了肿瘤中MDSCs的表型鉴定、扩增及活化机制、发挥免疫抑制作用的途径及机制、肿瘤中MDSCs的临床意义以及本领域需要解决的问题,以期对MDSCs在肿瘤免疫耐受中的作用进展提供参考.

Reivew: Recent Progress on MDSCs and Tumor Immune Tolerance

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of myeloid progenitor cells and immature myeloid cells at different stages that are blocked from differentiating into mature myeloid cells under certain pathological conditions, such as cancer. They can exert a strong and broad-spectrum immunosuppressive function, and are regarded as one of the most important negative regulators of the immune system. It has been shown that a variety of cytokines and growth factors in the tumor environment can induce MDSCs expansion and activation through activating certain signaling pathways. Then, MDSCs use multiple mechanisms to suppress the functions of various immune cells, especially T cells, thus promoting immune tolerance to tumors. Clinical studies demonstrated that the levels of MDSCs in cancer patients was closely correlated with tumor clinical progression, and the immunotherapies targeting MDSCs are expected to become novel strategies against cancer. Here, we reviewed the recent progress about MDSCs and tumor immune tolerance, including MDSCs identification, mechanisms of MDSCs expansion and activation, mechanisms of MDSCs' immunosuppressive capability, as well as the clinical significance of MDSCs in cancer. We also discussed the remaining issues in this field that need to be elucidated.