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  • Open Access

IgE cross-reactivity between the major peanut allergen Ara h 2 and the non-homologous allergens Ara h 1 and Ara h 3

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Clinical and Translational Allergy20133 (Suppl 3) :P85

https://doi.org/10.1186/2045-7022-3-S3-P85

  • Published:

Keywords

  • Peptide
  • Inhibition Assay
  • Severe Reaction
  • Linear Sequence
  • Clinical Reactivity

Background

Ara h 1, a vicilin, Ara h 2, a 2S albumin, and Ara h 3, a legumin, are major peanut allergens. Ara h 2 was described as pre-eminent in importance, as it was identified as a predictor of clinical reactivity to peanut and more potent in degranulating basophils than Ara h 1 and Ara h 3. Co-sensitization to Ara h 2 and Ara h 1 and/or Ara h 3 appeared to be predictive of more severe reactions.

We investigated whether co-sensitization to the three major peanut allergens is due to cross-reactivity among them, despite the fact that 2S albumins and cupins do not display obvious linear sequence identities and structural similarities.

Methods

IgE cross-inhibitions were performed with IgG-depleted sera from 10 peanut-allergic subjects. using highly purified Ara h 1, Ara h 2, and Ara h 3. Following an in silico search for similar peptides, 4 peptides were synthesized which comprised the N-terminal region and the long loop between helices 2 and 3 of Ara h 2 and tested by IgE ELISA inhibition assay.

Results

Ara h 2 inhibited IgE binding to Ara h 1 (average 86% ± 13%) and Ara h 3 (average 96% ± 6%), respectively. IgE binding to Ara h 2 was inhibited by Ara h 1 by 78 % ± 15% and by Ara h 3 by 80% ± 6%. A comparison of Ara h 1 and Ara h 3 sequences with Ara h 2.0201 yielded four surface exposed regions on the Ara h 2 sequence which matched similar peptides on Ara h 1 and/or Ara h 3. IgE binding to Ara h 2-derived peptides was completely inhibited by Ara h 1 and Ara h 3. A mixture of these peptides reduced IgE binding to Ara h 1 and Ara h 3 by 20-60% and to Ara h 2 by 49-89%.

Conclusion

Co-sensitization to the three major peanut allergens, Ara h 1, Ara h 2, and Ara h 3 is due to IgE cross-reactivity among them. Cross-reactive IgE comprises the major fraction of IgE-specific for these allergens. These IgE are directed against highly similar sequences on surface-exposed loops of Ara h 1, Ara h 2, and Ara h 3. Supported by grant SFB F46-B19 from Austrian Science Fund to K. Hoffmann Sommergruber.

Disclosure of interest

None declared.

Authors’ Affiliations

(1)
Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria
(2)
Karl Landsteiner Institute for Dermatological Research, St Poelten, Austria
(3)
Department of Paediatrics and Adolescent Medicine, Medical University of Vienna, Vienna, Austria
(4)
Department of Paediatrics, Respiratory and Allergic Disease Division, Medical University Graz, Graz, Austria
(5)
U.S. Department of Agriculture, Agricultural Research Service, Southern Regional Research Cente, New Orleans, LA, USA

Copyright

© Bublin et al; licensee BioMed Central Ltd. 2013

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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