Matousovic K, Mestecky J, Tomana M, Novak J
Interní klinika 2 lékarské fakulty UK a FN Motol, Praha.
Vnitr Lek. 2006 Mar;52(3):256-62.
Immunoglobulin A (IgA) is a dominant immunoglobulin of the mucosal surfaces, but it is also present in plasma. In men and in hominoid primates it occurs in two subclasses: IgA1 and IgA2. Circulating IgA is mostly IgA1 monomer, secretory IgA is mostly dimer or tetramer with varying content of IgA1 and IgA2 on individual mucosal surfaces. Its main physiological function is a defence of the mucosal surfaces against infection. It binds either specifically to bacterial antigens or through its O-linked glycosidic chains, it binds to the lectins of bacterial cells and thus protects mucosal surfaces against bacterial adhesion and infection. On each of its heavy chain, IgA1 has at least two N-glycosidically bound oligosaccharides and 3 to 5 O-linked side-chains. The occurrence of O-glycosidically bound glycans on other circulating immunoglobulins is rare. An aberrant composition of these glycans may be an antigenic determinant for naturally occurring circulating antibodies. The resulting IgA-containing immune complexes, which are deposited in the glomeruli, may be the cause of IgA nephropathy. IgA glomerular deposits are also frequently present in many other primary and systemic glomerulonephritides.
免疫球蛋白A（IgA）是黏膜表面的主要免疫球蛋白，但也存在于血浆中。在男性和类人猿灵长类动物中，它以两种亚类形式存在：IgA1和IgA2。循环中的IgA主要是IgA1单体，分泌型IgA主要是二聚体或四聚体，在各个黏膜表面上IgA1和IgA2的含量各不相同。其主要生理功能是保护黏膜表面免受感染。它要么特异性地结合细菌抗原，要么通过其O-连接糖苷链与细菌细胞的凝集素结合，从而保护黏膜表面免受细菌黏附和感染。在其每条重链上，IgA1至少有两个N-糖苷键连接的寡糖和3至5个O-连接侧链。其他循环免疫球蛋白上O-糖苷键连接聚糖的情况很少见。这些聚糖的异常组成可能是天然存在的循环抗体的抗原决定簇。由此产生的含IgA免疫复合物沉积在肾小球中，可能是IgA肾病的病因。IgA肾小球沉积物也经常出现在许多其他原发性和全身性肾小球肾炎中。
