Related Experiment Videos
IgG subclass response to immunization with Haemophilus influenzae type b polysaccharide-outer membrane protein
D M Granoff1, G A Weinberg, P G Shackelford
1Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, Children's Hospital, St. Louis, Missouri 63110.
Insights
Children receiving Haemophilus influenzae type b polysaccharide vaccines showed varied antibody responses. Conjugate vaccines in infants produced primarily IgG1 antibodies, while older children and boosted groups showed both IgG1 and IgG2 responses.
Area of Science:
- Immunology
- Vaccinology
- Pediatrics
Background:
- Haemophilus influenzae type b (Hib) is a significant cause of bacterial meningitis in young children.
- Antibody subclass responses, particularly IgG1 and IgG2, are crucial for effective immunity against polysaccharide antigens.
- The immunogenicity of Hib polysaccharide vaccines can be enhanced by conjugation to carrier proteins.
Purpose of the Study:
- To compare the IgG subclass (IgG1 and IgG2) antibody responses to Haemophilus influenzae type b polysaccharide in children immunized with conventional polysaccharide vaccine versus a conjugate vaccine.
- To evaluate the antibody response after primary immunization and booster doses in different age groups.
Main Methods:
- Enzyme-linked immunosorbent assay (ELISA) was used to measure IgG, IgG1, and IgG2 antibody concentrations in post-immunization sera from 117 children.
- Children were immunized with either a conventional Hib polysaccharide vaccine or a Hib conjugate vaccine (polysaccharide coupled to an outer membrane protein).
- Age groups included infants (2-17 months) and older children (24-83 months), with some receiving primary immunization and others a booster dose.
Main Results:
- Children (24-83 months) receiving the conventional Hib polysaccharide vaccine showed IgG responses composed of both IgG1 and IgG2 subclasses.
- Infants (2-17 months) immunized with the conjugate vaccine had predominantly or exclusively IgG1 antibody responses.
- Children primed with conjugate vaccine and boosted approximately one year later demonstrated robust memory responses with both IgG1 and IgG2 subclasses, regardless of whether boosted with polysaccharide or conjugate vaccine.
Conclusions:
- Conventional Hib polysaccharide vaccine in older children elicits both IgG1 and IgG2 responses, with a slight IgG1 predominance.
- Hib conjugate vaccine in infants induces a predominantly IgG1 response, suggesting a T-cell dependent mechanism.
- Both vaccine types elicit effective memory responses upon boosting, characterized by significant IgG1 and IgG2 subclass production.
Abstract:
We immunized 117 children with either Haemophilus influenzae type b polysaccharide vaccine or type b polysaccharide coupled to an outer membrane protein of group B Neisseria meningitidis (conjugate vaccine), and measured the IgG, IgG1, and IgG2 subclass composition of antibody to type b polysaccharide in postimmunization sera by ELISA. The IgG responses of 51 children, 24-83 months of age, immunized for the first time with the conventional type b vaccine consisted of both IgG1 and IgG2 antibody (respective geometric means of 2.24 and 0.77 micrograms/ml). In contrast, the IgG responses of 28 infants, 2-17 months of age, immunized with conjugate vaccine were predominantly or exclusively IgG1 (genometric mean IgG1 and IgG2 antibody concentrations of 1.92 and 0.19 micrograms/ml). A total of 38 children was primed with conjugate vaccine between 2 and 17 months of age and boosted approximately 1 yr later. The 28 children boosted with type b polysaccharide vaccine showed memory antibody responses consisting of both IgG1 and IgG2 (respective geometric means of 12.7 and 4.8 micrograms/ml); the 10 children boosted with conjugate vaccine showed a similar pattern of IgG subclass responses (respective geometric means of 20.8 and 5.1 micrograms/ml, p greater than 0.4 compared to the respective geometric mean IgG1 and IgG2 values of the group boosted with polysaccharide). Thus, in children 24-83 months of age, immunization with conventional type b polysaccharide vaccine generally elicits both IgG1 and IgG2 responses, with a slight predominance of IgG1.(ABSTRACT TRUNCATED AT 250 WORDS)