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United States Department of Agriculture

Agricultural Research Service

Research Project: Primary and Secondary Prevention of Peanut and Tree Nut Allergy

Location: Food Processing and Sensory Quality Research

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

Author
item Bublin, Merima
item Kostadinova, Maria
item Radauer, Christian
item Hafner, Christine
item Szepfalus, Zsolt
item Varga, Eva Maria
item Maleki, Soheila
item Vogel, Lothar
item Vieths, Stefan
item Hoffman-sommergruber, Karin

Submitted to: Journal of Allergy Clinical Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/18/2013
Publication Date: 7/5/2013
Citation: Bublin, M., Kostadinova, M., Radauer, C., Hafner, C., Szepfalus, Z., Varga, E., Maleki, S.J., Vogel, L., Vieths, S., Hoffman-Sommergruber, K. 2013. IgE cross-reactivity between the major peanut allergen Ara h 2 and the non-homologous allergens Ara h 1 and Ara h 3. Journal of Allergy Clinical Immunology. 132(1):118-124.

Interpretive Summary: Ara h 1, Ara h 2, and Ara h 3, are major peanut allergens. Ara h 2 is an important predictor of clinical reactivity to peanut, but co-sensitization to all three allergens is correlated with the severity of patients’ symptoms. We investigated whether co-sensitization to these three allergens is caused by immunoglobulin E (IgE) cross-reactivity, despite the fact that they do not display obvious structural or amino acid sequence similarities. Multiple cellular and molecular immunological experiments were performed with purified Ara h 1, Ara h 2, and Ara h 3, and serum IgE from 10 peanut-allergic subjects. Ara h 1 completely inhibited IgE binding to Ara h 2 (median 96%) and Ara h 3(median 100%), whereas, IgE binding to Ara h 1 and Ara h 3, was partially inhibited by Ara h2 (medians 81% and 73%). IgE binding affinity for Ara h 2 was greater than for Ara h 1 and Ara h 3. A comparison of sequences showed that these non-homologous peanut allergens contain several similar surface exposed peptides. 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 the capacity of the three allergens to induce histamine release (12-49%). Occurrence of similar amino acid sequences in the three major peanut allergens account for the high extent of cross-reactivity among them.

Technical Abstract: Ara h 1, a vicilin, Ara h 2, a 2S albumin, and Ara h 3, a legumin, are major33 peanut allergens. Ara h 2 is an important predictor of clinical reactivity to peanut, but co-sensitization to all three allergens is correlated with the severity of patients’ symptoms. We investigated whether co-sensitization to these three allergens is caused by IgE cross-reactivity, despite the fact that they do not display obvious structural or sequence similarities. IgE cross-inhibitions were performed using purified Ara h 1, Ara h 2, and Ara h 3, and sera from 10 peanut-allergic subjects. Following an in silico search for similar peptides, IgE binding inhibition and basophil activation assays, using synthetic peptides were performed. Ara h 1 completely inhibited IgE binding to Ara h 2 (median 96%) and Ara h 3 (median 100%), whereas, IgE binding to Ara h 1 and Ara h 3, was partially inhibited by Ara h 2 (medians 81% and 73%). IgE binding affinity for Ara h 2 was greater than for Ara h 1 and Ara h 3. A comparison of sequences showed that these non-homologous peanut allergens contain several similar surface exposed peptides. 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 the capacity of the three allergens to induce mediator release (12-49%). Occurrence of similar sequences in the three major peanut allergens account for the high extent of cross-reactivity among them.

Last Modified: 8/24/2016
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