Department of Clinical Laboratory Medicine, Kyoto University Hospital, Kyoto, Japan.
Department of Transfusion Medicine and Cell Therapy, Kyoto University Hospital, Kyoto, Japan.
J Immunol. 2022 Aug 1;209(3):498-509. doi: 10.4049/jimmunol.2100024. Epub 2022 Jul 15.
The mononuclear phagocyte system (MPS), composed of monocytes/macrophages and dendritic cells (DCs), plays a critical role at the interface of the innate and adaptive immune systems. However, the simplicity of MPS has been challenged recently by discoveries of novel cellular components. In the current study, we identified the CD135 subset of monocytes as a novel class of APCs in mice. CD135 monocytes were readily found in the bone marrow, spleen, and peripheral blood at steady state, and they expressed markers specific to DCs, including MHC class II and CD209a, along with markers for monocytes/macrophages. In addition, this subset phagocytosed bacteria and activated naive T lymphocytes, fulfilling the criteria for APCs. CD135 monocytes were derived directly from macrophage DC progenitors, not from common monocyte progenitors or other monocytes, suggesting that these are distinct from conventional monocytes. These findings facilitate our understanding of the MPS network that regulates immune responses for host defense.
单核吞噬细胞系统（MPS）由单核细胞/巨噬细胞和树突状细胞（DC）组成，在先天免疫和适应性免疫系统的界面中发挥着关键作用。然而，最近新的细胞成分的发现对 MPS 的简单性提出了挑战。在本研究中，我们在小鼠中鉴定出 CD135 单核细胞亚群作为一种新的 APC 群体。在稳态下，CD135 单核细胞很容易在骨髓、脾脏和外周血中被发现，它们表达 DC 特异性标志物，包括 MHC Ⅱ类和 CD209a，以及单核细胞/巨噬细胞标志物。此外，该亚群能够吞噬细菌并激活幼稚 T 淋巴细胞，符合 APC 的标准。CD135 单核细胞直接来源于巨噬细胞 DC 祖细胞，而不是来自普通单核细胞祖细胞或其他单核细胞，这表明它们与传统单核细胞不同。这些发现有助于我们理解调节宿主防御免疫反应的 MPS 网络。
