Langerhans cells in the human tympanic membrane in health and disease: a morphometric analysis.

HYPOTHESIS: The normal tympanic membrane contains Langerhans dendritic cells, and they play a role in the pathogenesis of chronic suppurative otitis media. BACKGROUND: The presence of Langerhans dendritic cells in the normal tympanic membrane is disputed. However, they have been identified in tympanic membranes of patients with otitis media. A quantitative analysis of the distribution and morphology of these cells in the types of chronic suppurative otitis media has not been undertaken. METHODS: Samples of normal cadaveric tympanic membranes and those from patients with chronic suppurative otitis media of the tubotympanic and atticoantral varieties were stained with the immunohistochemical marker CD1a. The number of cells per unit length of basement membrane, diameters of cells, and number and length of dendritic processes were compared between the groups. RESULTS: CD1a-positive Langerhans dendritic cells were present in the normal tympanic membrane. The number of cells per unit length of basement membrane, diameters of cells, and the length of dendritic processes increased significantly in tubotympanic disease and in atticoantral disease, the difference being more pronounced in the latter form of otitis media. CONCLUSION: Langerhans cells are present in the normal tympanic membrane, and they probably play differing roles in the pathogenesis of tubotympanic and atticoantral forms of chronic suppurative otitis media.