[Experimental studies on allergic otitis media].

Experimental acute otitis media was produced by injecting various agents into the middle ear cavity of the guinea-pig and the animal was sacrificed for histological studies after 7 days of careful observation. The results are summarized as follows: 1) The introduction of bacteria suspension, egg albumin or milk into the healthy middle ear cavity produced the proliferation of the connective tissue and the infiltation of neutrophilic leucocytes in the mucosa, The secretion in the middle ear mostly consisted of the neutrophilic leucocytes. The introduction of egg albumin and milk produced a milder inflammation as compared with that of bacteria. No eosinophilic leucocytes were found in the lesion of these series. 2) In the guinea-pigs sensitized with egg albumin or milk, the introduction of the antigen agents into the middle ear cavity led to the allergic changes characterized by the edema, hemornhage, vascular dilatation, production of fibrin and the infiltration of eosinophilic leuco-cytes in the tympanic membrane or mucosa of fhe tympanic cavity. The secretion was also characterized by fibrin clots, blood, and eosinophilic cells. 3) When the egg albumin was employed as the antigen, the pathologic process was characterized by high degree of edema, while with milk it is characterized by hemorrhage and fibrinous exudation. It is evident that different antigen gives rise to different histopathologic manifestations. 4) The injection of bacteria suspension into the tympanic cavity of the sensitized guinea-pig resulted in the edema, vascular dilatation, eosinophilic infiltration and hemorrhage, which are similar to the allergic response of the tympanic membrane or the mucosa of the cavity. However, these changes are much milder as compared with those produced by true antigen-antibody reaction. The edema, in some instances, was absent. Neutrophilic leucocytes are the chief constituent of the middle ear secretion, but in many instances, fibrin clots and eosinophilic cells were demonstrated. It is clear that the sensitized mucous membrane differs entirely in the reaction to bacteria from the intact membrane. 5) In non-allergic reaction, eosinophilic cells are scarcely detected in the tissue or secretion, but in allergic response, eosinophilic leucocytes are demonstrable in all instances. It is, therfore, considered that the presence of eosinophilic cells in case of acute otitis media is characteristic to the allergic nature of the inflammation.