Lamm M E
Institute of Pathology, Case Western Reserve University, Cleveland, Ohio 44106, USA.
Am J Physiol. 1998 Apr;274(4):G614-7. doi: 10.1152/ajpgi.1998.274.4.g614.
The humoral arm of the mucosal immune system is principally composed of locally synthesized polymeric IgA, whose Fc portion is adapted for binding to the polymeric immunoglobulin receptor that is expressed on the basolateral surface of mucosal epithelial cells, including enterocytes. This receptor mediates the endocytosis and transcytosis of polymeric IgA, which allows IgA to function in host defense at three anatomic levels in relation to mucosal epithelium: IgA antibodies in the lamina propria can bind antigens and excrete them through the epithelium into the lumen; antiviral IgA antibodies in transit through epithelial cells can inhibit virus production by an intracellular action; and IgA antibodies secreted into the lumen can prevent antigens and microbes from adhering to and penetrating the epithelium. The ways in which IgA antibodies function in mucous membranes provide challenging investigative opportunities for cell physiologists and cell biologists.
黏膜免疫系统的体液分支主要由局部合成的聚合型IgA组成，其Fc部分适于与黏膜上皮细胞（包括肠上皮细胞）基底外侧表面表达的聚合免疫球蛋白受体结合。该受体介导聚合型IgA的内吞作用和转胞吞作用，使IgA能够在与黏膜上皮相关的三个解剖学水平上发挥宿主防御功能：固有层中的IgA抗体可结合抗原并通过上皮细胞将其排泄到管腔中；通过上皮细胞转运的抗病毒IgA抗体可通过细胞内作用抑制病毒产生；分泌到管腔中的IgA抗体可防止抗原和微生物黏附并穿透上皮细胞。IgA抗体在黏膜中发挥作用的方式为细胞生理学家和细胞生物学家提供了具有挑战性的研究机会。
