Macpherson A J, McCoy K D, Johansen F-E, Brandtzaeg P
Department of Medicine, McMaster University Medical Centre, Hamilton, Ontario, Canada.
Mucosal Immunol. 2008 Jan;1(1):11-22. doi: 10.1038/mi.2007.6.
The production of immunoglobulin A (IgA) in mammals exceeds all other isotypes, and it is mostly exported across mucous membranes. The discovery of IgA and the realization that it dominates humoral mucosal immunity, in contrast to the IgG dominance of the systemic immune system, was early evidence for the distinct nature of mucosal immunology. It is now clear that IgA can function in high-affinity modes for neutralization of toxins and pathogenic microbes, and as a low-affinity system to contain the dense commensal microbiota within the intestinal lumen. The basic map of induction of IgA B cells in the Peyer's patches, which then circulate through the lymph and bloodstream to seed the mucosa with precursors of plasma cells that produce dimeric IgA for export through the intestinal epithelium, has been known for more than 30 years. In this review, we discuss the mechanisms underlying selective IgA induction of mucosal B cells for IgA production and the immune geography of their homing characteristics. We also review the functionality of secretory IgA directed against both commensal organisms and pathogens.
哺乳动物体内免疫球蛋白A（IgA）的产量超过所有其他同种型，并且大部分通过粘膜输出。IgA的发现以及认识到它在体液粘膜免疫中占主导地位，这与全身免疫系统中IgG占主导地位形成对比，是粘膜免疫学独特性质的早期证据。现在很清楚，IgA可以以高亲和力模式发挥作用，用于中和毒素和致病微生物，并作为一种低亲和力系统，将密集的共生微生物群限制在肠腔内。30多年来，人们已经了解了派尔集合淋巴结中IgA B细胞的诱导基本图谱，这些细胞随后通过淋巴和血液循环，为粘膜提供浆细胞前体，这些浆细胞产生二聚体IgA，通过肠上皮细胞输出。在这篇综述中，我们讨论了粘膜B细胞选择性诱导产生IgA的潜在机制及其归巢特征的免疫地理学。我们还综述了针对共生生物和病原体的分泌型IgA的功能。
