Wold A E, Mestecky J, Tomana M, Kobata A, Ohbayashi H, Endo T, Edén C S
Department of Clinical Immunology, University of Goteborg, Sweden.
Infect Immun. 1990 Sep;58(9):3073-7. doi: 10.1128/iai.58.9.3073-3077.1990.
Type 1 fimbriae with mannose-specific lectins are widely distributed among members of the family Enterobacteriaceae and confer the ability to attach to a range of host cells, including colonic epithelial cells. The mucosal surfaces are protected by secretory immunoglobulin A (IgA), which agglutinates microorganisms and prevents their attachment to host epithelial cells. This action has been attributed to a specificity of the antigen-combining site of mucosal immunoglobulins for bacterial and viral surface components. Here, we report a novel mechanism for the antibacterial effect of secretory IgA. Secretory IgA and IgA myeloma proteins, especially those of the IgA2 subclass, were shown to possess carbohydrate receptors for the mannose-specific lectin of type 1-fimbriated Escherichia coli. The presence of the high-mannose oligosaccharide chain Man alpha 1-6(Man alpha 1-3)Man alpha 1-6(Man alpha 1-3)Man beta 1-4GlcNAc beta 1-4GlcNAc correlated with binding activity. The interaction between bacterial mannose-specific lectins and IgA receptor oligosaccharide resulted in agglutination of the bacteria and in inhibition of bacterial attachment to colonic epithelial cells. Thus, this interaction could form the basis for a broad antibacterial function of secretory IgA against enterobacteria regardless of the specificity of antibody molecules.
带有甘露糖特异性凝集素的1型菌毛广泛分布于肠杆菌科成员中，赋予细菌附着于一系列宿主细胞的能力，包括结肠上皮细胞。黏膜表面受到分泌型免疫球蛋白A（IgA）的保护，IgA可凝集微生物并阻止它们附着于宿主上皮细胞。这种作用归因于黏膜免疫球蛋白抗原结合位点对细菌和病毒表面成分的特异性。在此，我们报道了分泌型IgA抗菌作用的一种新机制。分泌型IgA和IgA骨髓瘤蛋白，尤其是IgA2亚类的蛋白，被证明对1型菌毛化大肠杆菌的甘露糖特异性凝集素具有碳水化合物受体。高甘露糖寡糖链Manα1-6(Manα1-3)Manα1-6(Manα1-3)Manβ1-4GlcNAcβ1-4GlcNAc的存在与结合活性相关。细菌甘露糖特异性凝集素与IgA受体寡糖之间的相互作用导致细菌凝集，并抑制细菌附着于结肠上皮细胞。因此，这种相互作用可能构成分泌型IgA针对肠杆菌的广泛抗菌功能的基础，而与抗体分子的特异性无关。
