R.K. Mellon Institute for Pediatric Research, Department of Pediatrics, Division of Infectious Diseases, UPMC Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, Pennsylvania 15224, USA; email:
Department of Pathology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA; email:
Annu Rev Immunol. 2021 Apr 26;39:695-718. doi: 10.1146/annurev-immunol-102119-074236. Epub 2021 Mar 1.
Among antibodies, IgA is unique because it has evolved to be secreted onto mucosal surfaces. The structure of IgA and the associated secretory component allow IgA to survive the highly proteolytic environment of mucosal surfaces but also substantially limit IgA's ability to activate effector functions on immune cells. Despite these characteristics, IgA is critical for both preventing enteric infections and shaping the local microbiome. IgA's function is determined by a distinct antigen-binding repertoire, composed of antibodies with a variety of specificities, from permissive polyspecificity to cross-reactivity to exquisite specificity to a single epitope, which act together to regulate intestinal bacteria. Development of the unique function and specificities of IgA is shaped by local cues provided by the gut-associated lymphoid tissue, driven by the constantly changing environment of the intestine and microbiota.
在抗体中，IgA 是独一无二的，因为它已经进化为分泌到黏膜表面。IgA 的结构和相关的分泌成分允许 IgA 在黏膜表面高度蛋白水解的环境中存活，但也大大限制了 IgA 在免疫细胞上激活效应功能的能力。尽管具有这些特性，但 IgA 对于预防肠道感染和塑造局部微生物组都至关重要。IgA 的功能由独特的抗原结合库决定，该库由具有各种特异性的抗体组成，从允许的多特异性到交叉反应性到对单个表位的特异性，共同作用以调节肠道细菌。IgA 的独特功能和特异性的发展受到肠道相关淋巴组织提供的局部线索的影响，这些线索由肠道和微生物群不断变化的环境驱动。
