Cellular events in relation to bacteria-specific antibodies in middle ear effusion during acute otitis media

The proportions of neutrophils and lymphocytes, the total number of viable lymphocytes and their spontaneous proliferating activity as well as the proportion of B-cells were determined in 238 middle ear effusion (MEE) samples from 124 ears and in 40 serum samples of 85 children in relation to the presence of bacteria-specific antibodies in MEE and the clinical outcome of acute otitis media (AOM) during the course of AOM. The percentage of lymphocytes was higher, and that of the neutrophils lower, in the ears with bacteria-specific antibodies than in the ears with no antibodies. The higher proportion of MEE lymphocytes and the presence of antibodies correlated to the faster resolution of AOM. Moreover, the total number of viable lymphocytes and the proliferating activity of these cells were related to the presence of specific antibodies in MEE. The findings of this study underline the importance of local mucosal immunity taking place in the middle ear in connection with bacteria-specific antibodies in resting AOM.