Role of mast cells in otitis media

Background: New pathophysiologic concepts are needed to explain the clinically observed connection between the allergic diathesis and otitis media. Although mast cells, unlike lymphocytes, are common in the normal middle ear mucosa, their potential role in innate immunity of the middle ear and in the expression of inflammatory responses in that space to bacterial challenge, as opposed to allergy, has received relatively little attention. Objective: In the current study, we examine the contributions of mast cells to the pathogenesis of bacterially induced inflammation in the middle ear and thus to otitis media. Methods: Wild-type mice, mast cell-deficient mice, and mast cell-deficient mice whose mast cell populations were restored by transplantation of bone marrow-derived mast cells were challenged by using models of bacterial and allergic middle ear inflammation. Results: Our results indicate that mast cells account for a substantial proportion of the innate immune response to bacteria in the middle ear. Conclusion: This mechanism may link responses to allergy and infection in the middle ear mucosa, and thus the mast cell may be a critical control element in the pathogenesis of otitis media.