Reboldi Andrea, Cyster Jason G
Howard Hughes Medical Institute and Department of Microbiology and Immunology, University of California San Francisco, San Francisco, CA, USA.
Immunol Rev. 2016 May;271(1):230-45. doi: 10.1111/imr.12400.
Secondary lymphoid tissues share the important function of bringing together antigens and rare antigen-specific lymphocytes to foster induction of adaptive immune responses. Peyer's patches (PPs) are unique compared to other secondary lymphoid tissues in their continual exposure to an enormous diversity of microbiome- and food-derived antigens and in the types of pathogens they encounter. Antigens are delivered to PPs by specialized microfold (M) epithelial cells and they may be captured and presented by resident dendritic cells (DCs). In accord with their state of chronic microbial antigen exposure, PPs exhibit continual germinal center (GC) activity. These GCs not only contribute to the generation of B cells and plasma cells producing somatically mutated gut antigen-specific IgA antibodies but have also been suggested to support non-specific antigen diversification of the B-cell repertoire. Here, we review current understanding of how PPs foster B-cell encounters with antigen, how they favor isotype switching to the secretory IgA isotype, and how their GC responses may uniquely contribute to mucosal immunity.
次级淋巴组织具有将抗原和罕见的抗原特异性淋巴细胞聚集在一起的重要功能，以促进适应性免疫反应的诱导。与其他次级淋巴组织相比，派尔集合淋巴结（PPs）具有独特之处，即它们持续暴露于种类繁多的微生物群和食物来源的抗原中，以及它们所遇到的病原体类型。抗原由特化的微褶（M）上皮细胞递送至PPs，并且它们可能被驻留的树突状细胞（DCs）捕获并呈递。鉴于其慢性微生物抗原暴露状态，PPs表现出持续的生发中心（GC）活性。这些GC不仅有助于产生产生体细胞突变的肠道抗原特异性IgA抗体的B细胞和浆细胞，而且还被认为支持B细胞库的非特异性抗原多样化。在这里，我们综述了目前对PPs如何促进B细胞与抗原相遇、如何促进向分泌型IgA同种型的同种型转换以及它们的GC反应如何独特地促进黏膜免疫的理解。
