1

Serves an effector function st mucous membrane surfaces (main entry sites for most pathogenic organisms).

2

Because it is polymeric, secretory IgA can cross-link large antigens with multiple epitopes

3

Binding of secretory IgA to bacterial and viral surface antigens prevents attachment of the pathogens to the mucosal cells.

5

Provide an important line of defense against pathogens.

4

Complexes of secretory IgA and antigen are easily entrapped in mucus and then eliminated by the ciliated epithelial cells.