Immunohistochemical study of murine middle ear and Eustachian tube

The localization of the immunocompetent cells and secretory component (SC) of the middle ear and Eustachian tube (ET) was investigated in healthy, non-immunized BALB/c mice, using immunohistochemical methods. Utilizing specific antisera against murine cell associated antigens and SC, we investigated the distribution of macrophages and granulocytes (Mac-1+ cells), helper T cells (Lyt-1+ cells), suppressor/cytotoxic T cells (Lyt-2+ cells), immunoglobulin-bearing cells (IgA, IgG, IgM) and SC in the middle ear and ET. Mac-1+ cells were found to be the most predominant cell type, followed in descending order by Lyt-1+ cells, IgA+ cells, Lyt-2+ cells, IgG+ cells and IgM+ cells. Lyt-1+ cells were found in the lamina propria, whereas Lyt-2+ cells were detectable in the epithelium of the ET. SC was seen predominantly within the tubal and glandular epithelial cells. These findings suggest that the distribution of the immunocompetent cells and SC in the ET is similar to that seen in secretory immune sites elsewhere in the body.