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，IgA以以成对或二聚体形式，也就是个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个亚型：IgA1和IgA2；IgA1主要存在于血清中，IgA2主要以二聚体形式存在于粘膜液中。