Abstract: Myeloid-derived suppressor cells (MDSCs) are a group of heterogeneous immature myeloid cells with immunosuppressive function. It is often mentioned in the study of tumor immune escape mechanism. In addition, MDSCs also participate in the immune regulation of chronic inflammation, infection, autoimmune diseases, trauma, and other diseases. Recent studies have found that MDSCs also play a key role in the pathogenesis of sepsis. Sepsis is a life-threatening organ failure caused by the imbalance of host immune response to infection. Studies have shown that compared with sepsis survivors, non-survivors have significantly reduced lymphocytes. In the early stage of sepsis, MDSCs are recruited to the inflammatory site to inhibit inflammation; however, if the number of MDSCs increases and its tissue infiltration persists, it can lead to significant pathophysiological changes (such as lymphopenia, host immunosuppression and immune paralysis), resulting in rapid progress or even worse of patients' condition. It can be seen that MDSCs provide new insights for lymphopenia in patients with sepsis, have become a new topic in sepsis research, and may provide new therapeutic targets for patients with sepsis. This article reviews the biological characteristics of MDSCs and its mechanism of action in sepsis immunosuppression, in order to provide new targets and ideas for the basic research and clinical treatment of sepsis.

Key words: Myeloid-derived suppressor cells, Sepsis, Immunosuppression, Targeted therapy

摘要： 髓源性抑制细胞（MDSCs）是一群异质性、具有免疫抑制功能的未成熟髓样细胞。常在肿瘤免疫逃避机制的研究中被提及，除此之外，MDSCs还参与慢性炎症、感染、自身免疫性疾病、创伤等疾病的免疫调节。最近研究发现，MDSCs在脓毒症的发病机制中也起着关键作用。脓毒症是由于宿主对感染的免疫反应失调而导致危及生命的器官功能衰竭。有研究表明，与脓毒症幸存者相比，非幸存者的淋巴细胞显著减少。在脓毒症发病早期，MDSCs被招募到炎症部位，起到抑制炎症的作用；然而，如果MDSCs数量增多及其组织浸润持续存在，可导致显著的病理生理学改变（如淋巴细胞减少、宿主免疫抑制和免疫瘫痪），从而导致患者病情快速进展甚至愈后恶化。由此可见，MDSCs为脓毒症患者淋巴细胞减少提供了新的见解，现已成为脓毒症研究的一个新兴课题，并可能为脓毒症患者提供新的治疗靶点。本文综述了MDSCs的生物学特征及其在脓毒症免疫抑制中的作用机制，以期为脓毒症的基础研究和临床治疗提供新的靶点和思路。

关键词: 髓源性抑制细胞, 脓毒症, 免疫抑制, 靶向治疗