Strategies of immunization against mucosal infections.

The presence of secretory (S-) IgA in middle-ear fluid and localization of IgA-secreting cells in its mucosae suggest that the middle ear is an effector site of the mucosal immune system. Several strategies have been devised to induce potent, long-lasting, and recallable mucosal S-IgA antibodies, as well as circulating IgG antibodies and Th1- or Th2-type help, according to the most appropriate responses for a particular infection. Application of immunogens to inductive sites in the upper respiratory tract may be most effective for generating responses in the middle ear and nasopharynx for protection against the organisms responsible for otitis media.