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Humoral immune responses to Neisseria meningitidis in children
A J Pollard1, R Galassini, E M van der Voort
1Departments of Paediatrics and Infectious Diseases & Microbiology, Imperial College School of Medicine, St. Mary's Hospital, London W2 1PG, United Kingdom. AJPollard@csi.com
Insights
Infants show poor immune response to meningococcal B infections, despite producing similar antibody levels to older children. This suggests qualitative antibody differences, not class switching failures, impact infant immunity to Neisseria meningitidis.
Area of Science:
- Immunology
- Pediatrics
- Microbiology
Background:
- Understanding childhood immunity to serogroup B meningococci is crucial for developing effective infant vaccines.
- Previous studies indicate suboptimal immune responses in infants, necessitating investigation into the underlying mechanisms.
Purpose of the Study:
- To investigate the characteristics of humoral immune responses to Neisseria meningitidis infection in relation to age.
- To identify factors contributing to poor vaccine responses in infancy.
Main Methods:
- Analysis of serum bactericidal activity in children of different age groups following Neisseria meningitidis infection.
- Measurement of total immunoglobulin G (IgG) and IgG subclass antibodies using enzyme-linked immunosorbent assay (ELISA).
Main Results:
- Serum bactericidal activity against serogroup B meningococci was significantly lower in children under 12 months compared to older children.
- Infants produced comparable levels of total IgG and specific IgG subclasses (IgG1 and IgG3) to older children.
- Highest bactericidal activity was observed in children over 10 years of age.
Conclusions:
- The age-dependent variation in bactericidal antibody response following meningococcal infection is not attributed to impaired immunoglobulin class switching in infants.
- Qualitative differences in antibody specificity or affinity may explain the reduced bactericidal capacity in infants.
Abstract:
An understanding of the nature of immunity to serogroup B meningococci in childhood is necessary in order to establish the reasons for poor responses to candidate vaccines in infancy. We sought to examine the nature of humoral immune responses following infection in relation to age. Serum bactericidal activity was poor in children under 12 months of age despite recent infection with Neisseria meningitidis. The highest levels of bactericidal activity were seen in children over 10 years of age. However, infants produced levels of total immunoglobulin G (IgG) and IgG subclass antibodies similar to those in older children in a meningococcal enzyme-linked immunosorbent assay. Most antibody was of the IgG1 and IgG3 subclasses. This striking age dependency of bactericidal antibody response following infection is not apparently due to failure of class switching in infants but might be due to qualitative differences in antibody specificity or affinity.