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Study of antibody levels in children with purulent otitis media
Insights
Children with recurrent acute otitis media often have high antibody levels (IgG, IgM) against bacteria like Haemophilus influenzae and Streptococcus pneumoniae, but these high titers do not always prevent reinfection.
Area of Science:
- Immunology
- Pediatrics
- Infectious Diseases
Background:
- Recurrent acute otitis media (AOM) is common in children.
- Bacterial pathogens in the nasopharynx are linked to AOM.
- Understanding the antibody response is crucial for managing AOM.
Purpose of the Study:
- To investigate serum antibody levels (IgG, IgM, IgA) in children with frequent AOM.
- To correlate antibody responses with specific bacterial antigens (Haemophilus influenzae, Streptococcus pneumoniae).
- To assess the protective efficacy of antibody titers against subsequent infections.
Main Methods:
- Studied children aged 9 months to 10 years with recurrent AOM.
- Measured serum IgG, IgM, and IgA antibody levels using enzyme-linked immunosorbent assay (ELISA).
- Tested against polysaccharide antigens from Haemophilus influenzae type b and Streptococcus pneumoniae types 3, 6, 19, 23.
Main Results:
- Most children exhibited high homologous antibody titers (IgG, IgM), especially during infection.
- High antibody titers (10^4-10^5) did not consistently prevent reinfection with the same bacterial type.
- Significant IgG and IgM titers against heterologous antigens were observed; IgA levels were generally lower and often undetectable.
Conclusions:
- Children with recurrent AOM possess robust, though not always protective, antibody responses.
- The presence of high antibody titers does not guarantee protection against subsequent AOM episodes.
- Further research is needed to understand the mechanisms of protection and susceptibility in recurrent AOM.
Abstract:
A series of episodes of acute otitis media were studied with reference to the bacterial findings in the nasopharynx and the specific antibody response in a group of children nine months to ten years of age, with previous frequent episodes of acute otitis media, Serum IgG, IgM and IgA antibody levels against five polysaccharide antigens, namely Haemophilus influenzae type b and Streptococcus pneumoniae types 3, 6, 19 and 23, were studied by means of an enzyme-linked immunosorbent assay. The selection of polysaccharide antigens was based on isolation frequency. The sera to be tested were tenfold serially diluted. An extinction of 0.2 over the base was taken as the end-point titer and expressed as in-log10. The results showed that most children including those under three years of age showed increasing homologous antibody titers at an infection, or had already initially very high antibody titers, especially of the IgG class. The titers reached levels of 10(4) to 10(5). In some cases, however, it could be shown that high serum antibody titers did not give protection against a new infection with the same serological type of bacteria. It was also demonstrated that most children, regardless of age, had IgG and IgM titers against the heterologous antigens. In some cases the levels were quite high (10(3) to 10(4)). However, the IgA antibody levels were lower and in a considerable number of samples antibodies were not even detectable.