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.

与其他抗体不同，IgA可以以成对体形式分，也就是两IgA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分两亚型：IgA1和IgA2；IgA1主要存在于血清中，IgA2主要以体形式存在于粘膜分液中。