Role of IgE in Eosinophilic Otitis Media

ABSTRACT: Eosinophilic otitis media (EOM) is an intractable otitis media characterized by the presence of a highly viscous yellow effusion containing eosinophils. It mainly occurs in patients with bronchial asthma and is resistant to conventional treatments for otitis media. Here we discuss the role of IgE in the pathogenesis of EOM. In middle ear effusion, a significantly higher IgE level was detected in EOM patients than in control patients with common otitis media with effusion. This IgE level was significantly higher (about 10 fold) than the serum IgE level. In addition, many IgE-immunopositive cells were found in the middle ear mucosa. The IgE staining was mainly observed on mast cell surfaces, but also partially in the cytoplasm of cells that appeared to be plasma cells. These results suggested that IgE is produced locally in the middle ear mucosa. The existence of high-level IgE may exacerbate eosinophilic inflammation in the middle ear. One of the most distinct characteristics of EOM is the high incidence of sensory hearing loss independent of age. High-tone hearing loss is more frequently found and more severe in EOM patients than in control patients with common chronic otitis media. The concentration of IgE in middle ear effusion significantly and positively correlated with bone conduction hearing levels at 2 kHz and 4 kHz in EOM patients. Overproduction of IgE locally in the middle ear may be related to the pathological condition of EOM and eventually cause inner ear damage. KEY WORDS: bronchial asthma, eosinophilic otitis media, eosinophils, IgE, sensory hearing loss