Kraal Georg, Samsom Janneke N, Mebius Reina E
Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, The Netherlands.
Immunol Rev. 2006 Oct;213:119-30. doi: 10.1111/j.1600-065X.2006.00429.x.
The immune system is organized as a number of distinct lymphoid organs interconnected by recirculating lymphocytes. These organs, such as lymph nodes, spleen, and gut-associated Peyer's patches, are compartmentalized, providing separate niches for T and B cells. In addition, regional compartmentalization of lymphoid organs themselves exists, leading to the distinction between the mucosal and the systemic immune systems. This distinction not only reflects the anatomical localization but also is based on functional differences, with predominant tolerance induction via mucosal routes and immunity seen after systemic antigen exposure. These differences are associated with regional differences in the lymphoid organs and with environmental conditions of the tissues in which the immune system functions. Recirculation patterns of lymphocytes differ between mucosal and systemic lymphoid organs, and more insight into the mechanisms that imprint this behavior has been generated recently. Differences in dendritic cells have been observed between mucosal and systemic sites, and knowledge on how local factors contribute to the immune system is emerging. From our studies on mucosal tolerance in mouse models, it has become evident that regional lymph nodes draining the mucosa are important sites to direct immune responses. Here, we discuss the way regional lymph nodes contribute to the direction of immune responses and what is known about the local factors and cell behavior that form the basis for these differences.
免疫系统由一些通过循环淋巴细胞相互连接的不同淋巴器官组成。这些器官，如淋巴结、脾脏和肠道相关的派尔集合淋巴结，是分隔的，为T细胞和B细胞提供了各自独立的微环境。此外，淋巴器官本身也存在区域分隔，导致了黏膜免疫系统和全身免疫系统的区分。这种区分不仅反映了解剖学定位，还基于功能差异，黏膜途径主要诱导耐受性，而全身抗原暴露后则出现免疫反应。这些差异与淋巴器官的区域差异以及免疫系统发挥功能的组织的环境条件有关。淋巴细胞在黏膜和全身淋巴器官之间的循环模式不同，最近人们对影响这种行为的机制有了更多了解。在黏膜和全身部位观察到树突状细胞存在差异，关于局部因素如何影响免疫系统的知识也不断涌现。从我们在小鼠模型中对黏膜耐受性的研究来看，很明显引流黏膜的区域淋巴结是指导免疫反应的重要部位。在这里，我们讨论区域淋巴结对免疫反应指导作用的方式，以及关于构成这些差异基础的局部因素和细胞行为的已知情况。
