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Antibody interactions with the capsule of Cryptococcus neoformans
M Feldmesser1, J Rivera, Y Kress
1Division of Infectious Diseases, Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, USA.
Infection and Immunity
|May 19, 2000
Summary
Monoclonal antibodies binding to Cryptococcus neoformans capsules can alter subsequent antibody detection. IgM antibodies bind outer capsule regions, while IgG antibodies show reduced binding to new fungal buds, impacting diagnostic imaging.
Area of Science:
- Immunology
- Microbiology
- Mycology
Background:
- Monoclonal antibodies (MAbs) targeting the Cryptococcus neoformans capsule exhibit diverse immunofluorescence (IF) patterns.
- Understanding MAb binding location is crucial for interpreting diagnostic assays and developing therapeutic strategies.
Purpose of the Study:
- To investigate the relationship between MAb binding location and observed IF patterns.
- To determine if MAb binding influences subsequent antibody interactions with the C. neoformans capsule.
Main Methods:
- Immunofluorescence (IF) and electron microscopy (EM) were employed to study two IgM MAbs (12A1, 13F1) and one IgG1 MAb (2H1).
- EM utilized tissue sections and cell suspensions for optimal capsule preservation and MAb localization.
- Direct and indirect IF assessed MAb binding variations in the presence of other MAbs.
Main Results:
- MAb binding location varied significantly between tissue sections and cell suspensions.
- In tissue sections, IgM MAbs (12A1, 13F1) bound throughout the capsule; in suspension, they bound to the surface.
- MAb binding altered subsequent primary and secondary antibody detection, and IgG1 MAb (2H1) showed reduced binding to fungal buds.
Conclusions:
- MAb binding to the C. neoformans capsule can modulate the binding of other antibodies.
- IgM MAbs primarily bind outer capsule regions, despite epitopes being present throughout.
- Differences in bud capsule suggest quantitative or qualitative variations affecting MAb 2H1 binding.