ANTIBODIES TO PNEUMOCOCCAL POLYSACCHARIDES IN HUMAN-MILK - LACK OF RELATIONSHIP TO COLONIZATION AND ACUTE OTITIS-MEDIA

Background. This study analyzed antibodies to pneumococcal polysacchar ides in human milk and their effect on nasopharyngeal colonization and acute otitis media in breast-fed infants. Methods. A total of 503 mil k samples were collected from 310 mothers. Nasopharyngeal cultures wer e obtained from their children at 2, 6 and 10 months postpartum, and t he capsular groups/types of the Streptococcus pneumoniae isolates were determined. Results. Types 6A, 6B, 19A, 19F and 23F accounted for 54% of the pneumococcal isolates, but type 3 isolates were uncommon. Milk samples were analyzed for antibody activity to the common capsular po lysaccharide types 6A, 19F and 23F; to the type 3 polysaccharide; to C -polysaccharide; and to phosphorylcholine (PC), a major component of t he pneumococcal cell wall polysaccharide (CWPS). Anti-capsular antibod y activity was low or absent in >90% of the milk samples. In contrast anti-PC antibody activity was detected in 88% and anti-CWPS in 84% of the samples. The frequency of acute otitis media did not vary with the milk anti-capsular, anti-PC or anti-CWPS antibody activity. Conclusio ns. There was no reduction in nasopharyngeal carriage of S. pneumoniae among children fed milk with anti-capsular or anti-PC antibody activi ty, but carriage was increased in those children who received milk wit h anti-CWPS antibody activity. A protective role of anti-polysaccharid e or anti-CWPS antibodies in milk was not detected under the study con ditions.