Local production of IgG to pneumococcal C-polysaccharide in upper airway secretions from children with recurrent acute otitis media.

Antibodies against C-polysaccharide (C-Ps), a common cell wall component of all pneumococci, may be of importance for the elimination of decaying pneumococci. By means of ELISA with phenylated C-Ps, anti-C-Ps IgG was measured in samples of plasma and upper airway secretions from otitis-prone children (OP), children with fewer episodes of recurrent acute otitis media (rAOM), and children with no previous history of AOM, but suffering from secretory otitis media (SOM). All children were free from acute illness at the time of sampling. No statistically significant differences of anti-C-Ps IgG in plasma or in nasopharyngeal secretions (NPS) were found between any of the groups. Based on calculations of the correlation between levels of anti-C-Ps IgG in plasma and NPS, and of the transudation ratios of anti-C-Ps IgG, total IgG, and albumin from plasma to NPS, we suggest that a significant amount of the anti-C-Ps IgG in NPS must be locally produced. The additional finding that OP children had significantly higher levels of anti-C-Ps IgG in their middle ear effusions (MEE) than SOM children points in the same direction. Anti-C-Ps IgA and IgM were detected in very low concentrations in plasma and secretion samples.