Anti pneumococcal antibody activity in nasopharyngeal secretions in healthy adults and children.

The local antibody activity to Streptococcus pneumoniae serotype 6B was measured in nasopharyngeal secretions from 20 healthy adults and 43 children, 1-3 years of age, 14 of whom were healthy and 29 were at risk for developing recurrent episodes of acute otitis media (RAOM) according to the criteria described below. In children, anti pneumococcal IgA and IgG antibody activity was of the same magnitude in both groups. Adults showed significantly higher specific IgA activity. Antibody activity of the IgG isotype was also higher in adults, possibly reflecting the higher serum antibody levels. The children at risk of developing RAOM had significantly higher levels of secretory component (SC) in their nasopharyngeal secretions. Our data suggest that local immunity in the nasopharynx is not fully developed in young children, which might contribute to bacterial survival and colonization in the region.