Functional Antibody Responses to Seven Serotypes in Pneumococcal Polysaccharide Vaccine in Children

Park, Ji Hye; Kim, Hee Jung; Hong, Young Mi; Kim, Kyung Hyo

Abstract

PURPOSE
Streptococcus pneumoniae is an important pathogen in children as well as in elderly people. The aim of this study was to assess the opsonization activity of pneumococal capsular antibody to seven serotypes in 23-valent pneumococcal polysaccharide vaccine before and after immunization in Korean children.
METHODS
Nine children from 24 to 49 months of age were immunized with 23-valent polysaccha ride pneumococcal vaccine in Ewha Woman's University Tongdaemoon Hospital. From them, sera were collected before immunization as well as 1 month after immunization. Double-serotype opsono phagocytic killing assay was performed against seven serotypes(4, 6B, 9V, 14, 18C, 19F and 23F) of S. pneumoniae to get opsonization titer of these sera using dimethyl formamide differentiated HL-60 cells.
RESULTS
After immunization, geometric mean opsonization titer of sera against serotype 18C(4,352) was the highest followed by serotype 9V(3,317), serotype 14(1,545), serotype 4(1,359). The opsonization titer against serotype 23F(342) was the lowest followed by serotype 19F(525), and serotype 6B (809). Fold increases of opsonization titer were higher against serotype 4(339.8), 9V(65.7), 19F(34.5), and 14(18.8) than those against serotype 23F(4.5), 6B(8.9), and 18C(9.9).
CONCLUSION
The opsonization titers of postimmune sera against seven serotypes of S. pneumoniae were increased in many(not all) preschool children. But they showed variable values of opsonization titer in postimmune sera as well as in preimmune sera against different serotypes. The immune responses to pneumococcal polysaccharide in preschool children are not maturated sufficiently yet.