Zhong Chao, Zheng Mingzhu, Zhu Jinfang
Institute of Systems Biomedicine, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, PR China.
Molecular and Cellular Immunoregulation Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
Cytokine Growth Factor Rev. 2018 Aug;42:5-12. doi: 10.1016/j.cytogfr.2018.02.004. Epub 2018 Feb 13.
Innate lymphoid cells (ILCs) that are capable of producing effector cytokines reminiscent of CD4 T helper (Th) cells during infections and tissue inflammations have drawn much attention in the immunology field in recent years. Within the ILCs, the lymphoid tissue inducer (LTi) cells that play a critical role in lymphoid organogenesis were identified long before the establishment of the ILC concept. LTi cells, developed and functioning mainly at the fetal stage, and LTi-like cells, presumably generated during the adulthood, are regarded as a subset of type 3 ILCs (ILC3s) because they express the ILC3 lineage-defining transcription factor RORγt, and like other ILC3s, can produce an ILC3 signature cytokine IL-22 and initiate protective immune responses against extracellular bacteria. However, LTi/LTi-like cells have a unique gene expression pattern, and they develop from a progenitor that is distinct from the progenitor of all other ILCs and the progenitor of conventional natural killer (cNK) cells. There are also several other unique features of LTi/LTi-like cells comparing to non-LTi ILC3s. In addition to their classical function in lymphoid organogenesis, LTi/LTi-like cells also have specialized functions in association with the adaptive immune system, which include their effects on T and B cell development, activation and function. In this review, we summarize these specific features of LTi/LTi-like cells and propose that these cells should be considered as a separated innate lymphoid lineage in parallel with other non-LTi ILCs and cNK cells.
近年来，在感染和组织炎症期间能够产生类似于CD4辅助性T（Th）细胞的效应细胞因子的固有淋巴细胞（ILC）在免疫学领域备受关注。在ILC中，早在ILC概念确立之前就已发现了在淋巴器官发生中起关键作用的淋巴组织诱导细胞（LTi）。主要在胎儿期发育并发挥功能的LTi细胞，以及推测在成年期产生的LTi样细胞，被视为3型ILC（ILC3）的一个亚群，因为它们表达ILC3谱系定义转录因子RORγt，并且与其他ILC3一样，能够产生ILC3特征性细胞因子IL-22，并启动针对细胞外细菌的保护性免疫反应。然而，LTi/LTi样细胞具有独特的基因表达模式，它们起源于一种不同于所有其他ILC祖细胞和传统自然杀伤（cNK）细胞祖细胞的祖细胞。与非LTi ILC3相比，LTi/LTi样细胞还有其他几个独特特征。除了在淋巴器官发生中的经典功能外，LTi/LTi样细胞在与适应性免疫系统相关方面也具有特殊功能，包括它们对T细胞和B细胞发育、激活及功能的影响。在本综述中，我们总结了LTi/LTi样细胞的这些特定特征，并提出应将这些细胞视为与其他非LTi ILC和cNK细胞平行的一个独立的固有淋巴细胞谱系。
