The middle ear mucosal immune system in otitis media with effusion.

The mucous membrane of the middle ear cavity in otitis media with effusion has a number of immunobiological mechanisms capable of defending the organ. A humoral immune mechanism, with all the attributes of a local mucosal immune system, appears to be present and capable of preventing viral and bacterial access to middle ear tissue. Putative cells of a cell-mediated immune response also appear to be present, and the distribution of T cells and B cells and T-helper and T-suppressor cells is described. The exact role of these cells in either cell-mediated immunity or delayed hypersensitivity remains to be defined in otitis media. Lymphocyte--macrophage interaction is briefly described and may represent an important aspect of immune modulation in the middle ear in otitis media with effusion. Finally, the effect of middle ear supernatants on natural killer cell activity is discussed. Serous effusions appear to augment natural killer cell activity of peripheral blood lymphocytes.