Unlike other antibodies, IgA can be secreted out in pairs, or a dimeric form called secretory IgA, which is literally two IgA antibodies attached together.

抗体不同，IgA可以以成对或二聚体形式分，也就是两个IgA连接在一起。

Now, IgA comes in subclasses—IgA1 and IgA2, IgA1 is found mainly in the serum while IgA2 is more often found in the mucus secretions, typically in its dimeric form.

IgA分两个亚：IgA1IgA2；IgA1要存在于血清中，IgA2要以二聚体形式存在于粘膜分液中。