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The unspecific antibody response to N. meningitidis group A capsular polysaccharide often seen in bacteraemic

H Käyhty

    Parasite Immunology
    |May 1, 1982
    PubMed

    Insights

    Unexpected antibody activity against Neisseria meningitidis group A (MenA) was found in patients with other bacterial infections. This non-specific immune response differed from true MenA infections and vaccine responses.

    Area of Science:

    • Immunology
    • Microbiology
    • Infectious Diseases

    Background:

    • Bacterial meningitis remains a significant global health concern.
    • Accurate diagnosis of bacterial meningitis relies on identifying the causative pathogen and host immune response.
    • Non-specific antibody cross-reactivity can complicate diagnostic interpretations.

    Purpose of the Study:

    • To investigate an observed rise in antibody activity against Neisseria meningitidis group A (MenA) capsular polysaccharide in patients with non-MenA bacteraemic infections.
    • To characterize the nature of this non-specific antibody response and differentiate it from specific immune reactions.

    Main Methods:

    • Analysis of acute and convalescent phase sera from patients with various bacteraemic and non-bacteraemic diseases.
    • Measurement of antibody binding activity to MenA capsular polysaccharide using radioactive antigen.
    • Characterization of antibody immunoglobulin classes (A, G, M) and avidity.
    • Inhibition assays using N-acetylmannosamine to assess antibody specificity.

    Main Results:

    • An unexpected increase in anti-MenA antibody activity was detected in 59/292 patients with infections caused by other bacteria (e.g., H. influenzae, S. pneumoniae).
    • This non-specific reactivity was absent in non-bacteraemic conditions and following certain vaccinations.
    • The 'unspecific' antibodies were of IgA, IgG, and IgM classes, exhibited lower avidity, and were significantly inhibited by N-acetylmannosamine.

    Conclusions:

    • A non-specific antibody response against Neisseria meningitidis group A capsular polysaccharide can occur during other bacterial infections.
    • This phenomenon highlights the potential for cross-reactivity in antibody-based diagnostics.
    • The distinct inhibition profile by N-acetylmannosamine suggests a different epitope or binding mechanism compared to specific anti-MenA antibodies.

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