Effect of early carriage of Streptococcus pneumoniae on the development of pneumococcal protein-specific cellular immune responses in infancy.

BACKGROUND

The aim of this study was to examine the relationship between nasopharyngeal pneumococcal colonization in early life and the subsequent development of pneumococcal-specific T cell responses.

METHODS

Pernasal swabs were collected from Papua New Guinean infants at the ages of 1 and 2 weeks (n = 279). At 9 months, in vitro cellular immune responses to choline-binding protein A (n = 132), pneumococcal surface protein A (n = 132), pneumolysin (n = 99), and the pneumococcal conjugate vaccine carrier CRM197 were determined. Responses were compared based on the children's carriage status within the first 2 weeks of life.

RESULTS

Within the first 2 weeks of life, 40% of the study children carried Streptococcus pneumoniae. Early carriage was associated with lower interferon-γ and interleukin 10 responses to pneumococcal proteins at age 9 months when children had not received pneumococcal conjugate vaccines during the study period.

CONCLUSIONS

Early pneumococcal carriage may result in enhanced disease susceptibility and suboptimal vaccine responses by modulating the development of pneumococcal immune responses.