Antibody Levels and Opsonophagocytic Function to S. pneumoniae 19F Capsular Polysaccharide

ABSTRACT

PURPOSE: The increasing prominence of pneumococcal infections and of antimicrobial resistance has emphasized the need for a effective vaccine to reduce the risk of pneumococcal disease in childhood. To study the antibody response of pneumococcal vaccine, we compared the concentration and opsonophagocytic capacity of antibodies to the capsular polysaccharide of S. pneumoniae serotype 19F in sera from healthy adults after immunization with 23-valent pneumococcal polysaccharide(PS) vaccine. METHODS: Thirty healthy adults were immunized with pneumococcal 23-valent PS vaccine. One month after vaccination, the amounts of total, IgG, IgG1, and IgG2 antibody were determined by enzyme-linked immunosorbent assay(ELISA). To investigate the function of anti-19F antibodies, the opsonization titer was determined by opsonophagocytic assay. RESULTS: The mean antibody levels of total immunoglobulin and IgG specific to 19F serotype were 21.9mg/mL and 16.2mg/mL, respectively. Most of the IgG anti-PS antibodies were IgG2 isotype. The mean value of opsonization titer was 229.1. The opsonization titer against the 19F serotype was strongly correlated with total immunoglobulin and IgG anti-19F antibody concentration. And IgG2 concentration was correlated more with opsonization titer than with IgG1. CONCLUSION: Antibody level may be of general use in predicting vaccine-induced protection among adults for 19F pneumococcus. This study should be extended to other serotypes and to assess the antibody response to new protein conjugate pneumococcal vaccine in young children.