Experimental Otitis Media in Mice:Immunohistochemical Observations

In order to identify T cells and B cells in the middle ear (ME) mucosa, immunohistochemical observations were performed on mice which were induced with immune-mediated otitis media with effusion (OME). C3H/HeN mice were challenged with dinitrophenylated ovalbumin in the ME, 2 weeks after the systemic immunization. At 1, 3 and 7 days post challenge, the mice were sacrificed, and IgG-, IgA- or IgM-positive cells, as well as Lyt-1- or Lyt-2-positive cells, were observed in the subepithelial layer of ME. IgG- or IgA-positive lymphocytes were detected at 7 days post challenge, whereas IgM-positive cells were rarely seen. At 3 days post challenge, the number of Lyt-1-positive lymphocytes exceeded that of Lyt-2-positive lymphocytes; however, at 7 days post challenge they were similar. Previous studies have suggested that immune complexes are a key factor in the generation of immune-mediated OME. However, it seems possible that delayed type hypersensitivity may contribute to the pathogenic mechanism of OME.