Immunologic responses to polysaccharides and polysaccharide–conjugate vaccines are complex

Abstract

The concurrent evaluations of pneumococcal nasopharyngeal colonization and responsiveness to pneumococcal polysaccharide-protein conjugate vaccine (PCV) provide insight into the complexity of immunologic responses. We knew that PCV affects colonization, and now we know that colonization affects PCV response. In the current study from the Netherlands, investigators found a dampening effect of carrying or having carried S pneumoniae in the nasopharynx on type-specific antibody response to PCV at 24 months of age. This phenomenon has been reported for young infants, particularly for those who had type-specific colonization prior to their first dose of PCV. Exhaustion of B lymphocytes (presumably “busy” reacting to colonizing strains) in immunologically immature infants was proposed as the mechanism of hyporesponsiveness. Finding the same dampening effect in 24-month old (presumably more immunologically mature) previously immunized/not previously immunized children who were found to be recently colonized with S penumoniae vaccine serotypes helps to clarify what seems to be complex and multifaceted bacterial polysaccharide–protein conjugate–host interactions. Clinical importance of diminished antibody response in the context of nasopharyngeal colonization is unknown. Article page 965▶ Lower Immunoglobulin G Antibody Responses to Pneumococcal Conjugate Vaccination at the Age of 2 Years after Previous Nasopharyngeal Carriage of Streptococcus pneumoniaeThe Journal of PediatricsVol. 159Issue 6PreviewTo determine whether nasopharyngeal pneumococcal carriage with serotypes 6B, 19F, or 23F interferes with immunoglobulin G (IgG) antibody responses to vaccination with 7-valent pneumococcal conjugate vaccine (PCV7) at the age 24 months. Full-Text PDF