Lymphocyte subpopulations in otitis media with effusion

The distribution of B and T lymphocytes and macrophages in the middle ear fluid (MEF) was studied in groups of children with otitis media associated with serous, seromucinous, or mucoid effusions in the middle ear. The subpopulations of T and B lymphocytes and macrophages were identified in the MEF by employing the techniques of spontaneous erythrocyte rosetting (E), membrane immunofluorescence, erythrocyte-amboceptor- complement (EAC) and erythrocyte-amboceptor (EA) rosette formation, respectively. A significant number of B and T lymphocytes or macrophages were detected in all specimens; however, certain differences were observed in their relative distribution in different types of effusions. Serous MEF was characterized by a cellular response associated predominantly with macrophages, although T lymphocytes were also seen frequently. No B lymphocytes were seen in such exudates. The seromucinous MEF contained B and T lymphocytes and macrophages in approximately similar proportions. Significantly, however, the mucoid effusion consisted mainly of B lymphocytes. Only macrophages and no T cells were observed in these effusions. The cytologic findings reported here may be helpful in a more definitive classification of middle ear effusions. These data may suggest a possible role of the different components of cellular immunity in the development of middle ear effusions. Speculation: E rosette-forming cells predominate in the serous and seromucinous effusions of otitis media. EAC rosette-forming cells appeared as a predominant cell type in mucoid effusions. The different types of effusions in otitis media may represent the various stages of the same inflammatory process. The differences in the types of immunocompetent cells observed may reflect the nature of the underlying immune response in serous, seromucinous, or mucoid forms of otitis media.