The tumor microenvironment (TME), which is mostly composed of tumor cells, immune cells, signaling molecules, stromal tissue, and the vascular system, is an integrated system that is conducive to the formation of tumors. TME heterogeneity makes the response to immunotherapy different in different tumors, such as "immune-cold" and "immune-hot" tumors. Tumor-associated macrophages, myeloid-derived suppressor cells, and regulatory T cells are the major suppressive immune cells and their different phenotypes interact and influence cancer cells by secreting different signaling factors, thus playing a key role in the formation of the TME as well as in the initiation, growth, and metastasis of cancer cells. Nanotechnology development has facilitated overcoming the obstacles that limit the further development of conventional immunotherapy, such as toxic side effects and lack of targeting. In this review, we focus on the role of three major suppressive immune cells in the TME as well as in tumor development, clinical trials of different drugs targeting immune cells, and different attempts to combine drugs with nanomaterials. The aim is to reveal the relationship between immunotherapy, immunosuppressive TME and nanomedicine, thus laying the foundation for further development of immunotherapy.

肿瘤微环境（TME）主要由肿瘤细胞、免疫细胞、信号分子、间质组织和血管系统组成，是一个有利于肿瘤形成的综合系统。TME异质性使得不同肿瘤对免疫治疗的反应不同，例如“免疫冷”和“免疫热”肿瘤。肿瘤相关巨噬细胞、髓源性抑制细胞和调节性T细胞是主要的抑制性免疫细胞，它们的不同表型通过分泌不同的信号因子相互作用和影响癌细胞，从而在TME的形成以及TME的形成中发挥关键作用。癌细胞的起始、生长和转移。纳米技术的发展有助于克服限制常规免疫疗法进一步发展的障碍，例如毒副作用和缺乏靶向性。在这篇综述中，我们重点关注三种主要的抑制性免疫细胞在 TME 以及肿瘤发展中的作用、针对免疫细胞的不同药物的临床试验，以及药物与纳米材料结合的不同尝试。目的是揭示免疫治疗、免疫抑制TME和纳米医学之间的关系，从而为免疫治疗的进一步发展奠定基础。