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Characterization of polyclonal allergen-specific IgE responses by affinity distributions
L K Pierson-Mullany1, D R Jackola, M N Blumenthal
1Department of Medicine, The Asthma and Allergy Center, University of Minnesota Medical School, Box 434 Mayo, 420 Delaware Street S.E., Minneapolis, MN 55455, USA.
Molecular Immunology
|February 13, 2001
Summary
High-affinity IgE antibodies target a few specific epitopes in allergic individuals. This uniform immune response suggests epitope structure, not individual variation, dictates antibody affinity to allergens like ragweed and dust mite.
Area of Science:
- Immunology
- Allergy Research
- Molecular Biology
Background:
- Polyclonal IgE responses are typically assessed by antibody levels and epitope sequences.
- However, the binding affinities of these IgE antibody families remain largely uncharacterized.
- Understanding IgE binding affinities is crucial for a comprehensive understanding of allergic reactions.
Purpose of the Study:
- To investigate the binding affinities of allergen-specific IgE antibodies.
- To characterize the polyclonal IgE response to specific allergens (Amb a 1 and Der p 1).
- To determine if individual immune responses or epitope structure influences IgE binding affinity.
Main Methods:
- Sera from allergic donors were used to study binding reactions between purified allergens (Amb a 1, Der p 1) and specific IgE.
- Affinity distribution functions were determined to analyze binding affinities.
- Peptide fragments of Der p 1 epitopes were used to inhibit IgE binding and characterize polyclonal interactions.
Main Results:
- IgE affinity distributions showed a few dominant peaks, indicating a limited number of high-affinity reactions.
- Two dominant peaks were observed in all donors, with a third peak in two-thirds of cases for both allergens.
- Peptide inhibition revealed that each peak corresponded to antibodies targeting a single epitope.
Conclusions:
- The IgE response in atopic individuals is surprisingly uniform, with the majority of the response being high-affinity.
- Approximately 70-80% of the IgE response is of high affinity (10^8–10^11 M⁻¹).
- Epitope structure, rather than individual immune response variations, appears to dictate the relative affinities of IgE antibodies to specific epitopes.