Cells Involved in the Middle Ear Defense System

Abstract

Despite the high incidence and prevalence of otitis media, its pathogenesis is not thoroughly understood. In the last decade, many efforts have been made to provide a better understanding, and abundant information has become available. At the same time the field of immunology has advanced at an extremely rapid pace. We have followed the gradual cellular events in the defense reaction of the middle ear, utilizing eustachian tube obstruction to induce otitis. Seventy-five cats were divided in groups and sacrificed at intervals between one day and six months, and their temporal bones were studied. During an initial phase of inflammation, polymorphonuclears appear at three days in connective tissue; at the same time active fibroblasts synthesize tropocollagen and ground substance while epithelial cells secrete mucus and lysozymes. These cells, together with those involved in the mucociliary transport system and a patent functional eustachian tube, constitute the nonspecific system of defense. The transition cells are the macrophages which appear at one week to interact with T and B cells to produce the specific immune response. Plasma cells appear at two weeks to peak at one month with synthesis of immunoglobulins A, G and M. A secretory immune system is observed. At three and six months, lymphocytes are the predominant cells and occasional accumulations of mononuclears are observed. The reaction involves the entire middle ear, including mucoperiosteum, middle ear muscles and round window membrane. We believe that a better understanding of the middle ear defense system will lead in time to a practical clinical assessment of the immunological status during the evolution of each particular process or disease involving the middle ear, and a more rational approach to the treatment and, hopefully, prevention of chronic ear disease.

Clinical Aspects of Round Window Membrane Permeability Under Normal and Pathological Conditions

“…Experimental evidence in cats and chinchillas (13,14) has shown the passage of cationic ferritin These changes, with the involvement of non-speci c and speci c defense factors (14), are suggestive of round window membrane participation in a middle ear (18), inner ear (19) and round window defense system.…”

“…In otitis media-induced cats, round window membrane changes have been evaluated by light mi- croscopy (15,16) and the membrane was observed to undergo gradual changes similar to those of the mucoperiostium (18,48). These changes suggest that perhaps, at early stages, there may be an increase in permeability but that, as the in ammatory process develops, the changes in the membrane become protective in terms of decreased permeability.…”

Gland Formation in Otitis Media. An Ultrastructural Study in Humans

“…In otitis media, histopathological changes are manifested in the epithelial and subepithelial layers and also in the form of middle ear effusions (7,9). These changes, which occur not only in the middle ear space and include, among others, increased goblet cell density and formation of new glands, granulation tissue and adhesions.…”

Middle ear effusion—A theoretical neuro mechanical hypotheses

“…In secretory otitis media, the mucosa shows an inflam-matory reaction (Sade, 1979C). However, this may be a non-specific reaction (Gaycoolea et al, 1980), as a response to an effusion which cannot be expelled (Zechner, 1980), or due to prostaglandins E. and F. found in the middle ear effusion (Jackson et al, 1975;Bernstein et al, 1976). There is increase in mucous glands and goblet cells (Sade, 1966B;Lim and Birck, 1971;Tos and Pederson, 1972).…”