Myeloid-derived suppressor cells (MDSCs) are notable innate immune cells, which are further divided into two subpopulations, i.e., monocytic and granulocytic. These cells are traditionally considered to mainly suppress the T-cell responses. However, more updated data indicate that their properties are rather immunomodulatory than solely immunosuppressive. Indeed, MDSCs display extensive crosstalk with other either innate or adaptive immune cells, and, according to the situation under which they are triggered, they may enhance or attenuate the immune response. However, their positive role in host's defense mechanisms under specific conditions is rarely discussed in the literature. In this mini-review, the authors briefly summarise the mechanisms of action of MDSCs under distinct conditions, such as infections and malignancies, with a particular emphasis on their role as components of the innate immunity system.

中文翻译：

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先天免疫背景下骨髓源性抑制细胞的免疫调节作用。

骨髓源性抑制细胞（MDSC）是著名的先天免疫细胞，其进一步分为两个亚群，即单核细胞和粒细胞。传统上认为这些细胞主要抑制 T 细胞反应。然而，更多更新的数据表明，它们的特性具有免疫调节作用，而不仅仅是免疫抑制作用。事实上，MDSC 与其他先天性或适应性免疫细胞表现出广泛的串扰，并且根据它们被触发的情况，它们可能会增强或减弱免疫反应。然而，文献中很少讨论它们在特定条件下对宿主防御机制的积极作用。在这篇小综述中，作者简要总结了 MDSC 在不同条件下（例如感染和恶性肿瘤）的作用机制，特别强调了它们作为先天免疫系统组成部分的作用。