Immunologically mediated and nonspecific inflammatory responses in the middle ear

Abstract

The immune response to antigens presented to the middle ear has been postulated as a factor in the pathogenesis of serous otitis media. We have previously described the immune response to keyhole limpet hemocyanin (KLH) presented to the middle ear in guinea pigs. In this report we describe the histologic and cytologic response in the middle ear cavity. KLH with or without alum was introduced into the middle ear. The nonspecific inflammation caused by alum alone served as comparison. No effusion was observed after any of these interventions. Large numbers of polymorphonuclear neuropils (PMNs) infiltrated the middle ear cavities of all subjects within 24 hours; this PMN response was gradually supplanted by lymphocytic and mononuclear cell infiltration. Eosinophils and basophils were noted only after introduction of antigen, with or without alum. All subjects showed submucosal edema and some degree of epithelial hyperplasia. Proliferation of respiratory epithelium was only seen after injection of alum with or without antigen. The appearance of plasma cells in the middle ear mucosa, indicating the development of a local immune response, was noted only after injection of antigen with alum adjuvant. The results indicate that both the development of a potent local immune response and the elicitation of a strong inflammatory response can occur in the middle ear without development of effusion.