Antibody production directed against pneumococci by immunocytes in the adenoid surface secretion

In previous studies of the adenoid surface secretion we revealed the presence of activated T cells, granulocytes engaged in phagocytosis and immunocytes that produce IgG, IgA and IgM. In the present study the objective was to assess the ability of these immunocytes to produce antibodies directed at S. pneumoniae.

Nine children subjected to adenoidectomy due to adenoid hypertrophy, secretory otitis media or recurrent otitis media were enrolled in the study. Samples of adenoid surface secretion were obtained by an imprint method and for comparison samples of adenoid tissue and peripheral blood were also obtained as well as a nasopharyngeal culture. Double-colour enzyme-linked immunospot (ELISPOT) assays were performed to detect total and pneumococci-specific IgG- and IgA-antibody secreting cells (ASC). In the adenoid tissue, the presence of H. influenzae type b specific ASC was also examined.

ASC were present in all nine samples of adenoid surface secretion with a dominance of IgG-ASC as compared to IgA-ASC. The proportion of ASC relative to the total number of lymphocytes was always greater in the secretion than in the corresponding adenoid tissue. The adenoid surface secretion samples from three of nine children contained IgG-ASC directed against S. pneumoniae. IgG-ASC directed against S. pneumoniae were detected in six of eight adenoids and IgA-ASC directed against S. pneumoniae were detected in two of eight adenoids. IgA-ASC directed against H. influenzae type b (Hib) were detected in one of seven adenoids.

The immunocytes in the adenoid surface secretion and the adenoid tissue itself hold the property to produce antibodies specific for known pathogens of the upper airways. These ASC are probably engaged in the immunologic defence of the nasopharyngeal mucosa and further studies are therefore called upon.