Mestecky J, Lue C, Russell M W
Department of Microbiology, University of Alabama, Birmingham.
Gastroenterol Clin North Am. 1991 Sep;20(3):441-71.
The principal characteristic immunoglobulin of mucosal surfaces, secretory immunoglobulin A (S-IgA), is the product of two different types of cell present in mucosal and glandular tissues. Submucosal plasma cells, which are generated largely within the common mucosal immune system, synthesize predominantly polymeric, J chain-containing IgA, which is selectively bound by polymeric immunoglobulin receptor or secretory component (SC) on the basolateral surfaces of mucosal and glandular epithelial cells. The molecular and cellular events involved in SC expression, its intravesicular transport together with its polymeric IgA ligand to the apical surface of the epithelial cell, during which IgA becomes covalently linked to SC, and the proteolytic cleavage of SC from the apical membrane to release S-IgA into the lumen have been elucidated. Additional receptors and mechanisms for the uptake, catabolism, and transport of IgA exist, especially in the liver. The biologic significance of IgA transport lies in the secretion of large quantities of S-IgA antibodies for the protection of huge areas of mucosal surfaces and for the provision of passive immunity to suckling infants, and in the immune elimination of antigenic materials by hepatobiliary transport.
黏膜表面的主要特征性免疫球蛋白，即分泌型免疫球蛋白A（S-IgA），是黏膜和腺组织中两种不同类型细胞的产物。黏膜下浆细胞主要在共同黏膜免疫系统内产生，主要合成聚合的、含J链的IgA，其被黏膜和腺上皮细胞基底外侧表面的聚合免疫球蛋白受体或分泌成分（SC）选择性结合。参与SC表达、其与聚合IgA配体一起向上皮细胞顶端表面的囊泡内转运（在此过程中IgA与SC共价连接）以及SC从顶端膜的蛋白水解切割以将S-IgA释放到管腔中的分子和细胞事件已得到阐明。存在其他用于IgA摄取、分解代谢和转运的受体及机制，尤其是在肝脏中。IgA转运的生物学意义在于分泌大量S-IgA抗体以保护大面积的黏膜表面并为哺乳婴儿提供被动免疫，以及通过肝胆转运进行抗原物质的免疫清除。
