Immune Response of the Inner Ear

Abstract

The etiopathogenesis of a large number of inner ear disease has not yet been clarified. Although immunologic injury was implicated in the pathogenesis of inner ear diseases in McCabe's case report, an autoimmune etiology was not proven due to the fact that the inner ear is an extremely small sensory organ. Recently, advances in the cellular and molecular analysis of immunological reactivity have been increasingly applied to diseases of the inner ear.
In this chapter, I first describe some animal models of immunologically mediated hearing loss and some clinical cases of sensorinerual hearing loss that might respond to immunosuppressive therapy. Second, experimental studies are discussed. Immune responses necessarily involve complement reactions, with the exception of type I allergic reactions. Complement is known to be related to many inflammatory reaction. C4a, C3a, and C5a, known as anaphylatoxin, are known to cause strong inflammatory reactions.
The role of anaphylatoxins on pathogenesis in the cochlea was examined, w ith atrophy of the stria vascularis, and endolymphatic hydrops, as well as other morphological changes clearly seen. These results were similar to the pathological changes observed in inner ear diseases in human being. Observation of inner ear inflammation due to specific and nonspecific immune responses is necessary.
Indeed, experimental evi d e nce establishing the operation of a distinct inner ear immune system is presented. However, though clinical cases may have an immunological basis a clear some etiology must be established.