Sensitization to the major allergen of Brazil nut is correlated with the clinical expression of allergy
ABSTRACT Only a few studies have investigated the clinical role of food allergens, especially the relationship between sensitization to a given allergen and occurrence of adverse reactions when eating the relevant food item.
This study evaluated the clinical role of the allergens of Brazil nut by comparing the patterns of IgE binding in sera from 11 patients with anaphylaxis after eating Brazil nuts with those from 10 subjects with no symptoms to this food item. Both groups had specific IgE to Brazil nut.
Allergens in the in-house extract of Brazil nut were identified by SDS-PAGE/immunoblotting, the major allergen was purified by HPLC, and its N-terminal sequence was determined by a protein sequencer.
SDS-PAGE/immunoblotting detected a number of allergenic components with molecular weights ranging from 4 to 58 kd. All sera from symptomatic patients recognized a 9-kd allergen corresponding (as established by amino acid sequencing) to a 2S albumin already described as a major allergen of Brazil nut, whereas the other allergens each bound IgE from less than 50% of sera. No sera from asymptomatic subjects showed IgE binding to the 9-kd allergen, but they did recognize components from 25 to 58 kd, which are minor allergens.
These findings indicate that the allergen underlying clinical reactions to Brazil nut is a 2S albumin of 9 kd and that in vitro reactivity to this allergen identifies subjects who react in vivo to ingestion of this food.
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ABSTRACT: It is not exactly known why certain food proteins are more likely to sensitize. One of the characteristics of most food allergens is that they are stable to the acidic and proteolytic conditions in the digestive tract. This property is thought to be a risk factor in allergic sensitization. The purpose of the present study was to investigate the contribution of the protein structure of 2S albumin (Ber e1), a major allergen from Brazil nut, on the sensitizing capacity in vivo using an oral Brown Norway rat food allergy model. Disulphide bridges of 2S albumin were reduced and alkylated resulting in loss of protein structure and an increased pepsin digestibility in vitro. Both native 2S albumin and reduced/alkylated 2S albumin were administered by daily gavage dosing (0.1 and 1 mg) to Brown Norway rats for 42 days. Intraperitoneal administration was used as a positive control. Sera were analysed by ELISA and passive cutaneous anaphylaxis. Oral exposure to native or reduced/alkylated 2S albumin resulted in specific IgG1 and IgG2a responses whereas only native 2S albumin induced specific IgE in this model, which was confirmed by passive cutaneous anaphylaxis. This study has shown that the disruption of the protein structure of Brazil nut 2S albumin decreased the sensitizing potential in a Brown Norway rat food allergy model, whereas the immunogenicity of 2S albumin remained preserved. This observation may open possibilities for developing immunotherapy for Brazil nut allergy.11/2013; 3(1):36. DOI:10.1186/2045-7022-3-36This article is viewable in ResearchGate's enriched formatRG Format enables you to read in context with side-by-side figures, citations, and feedback from experts in your field.
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ABSTRACT: Most of known allergenic proteins in rice (Oryza sativa) seed belong to Tryp_alpha_amyl family (PF00234). But the sequence characterization and the evolution of the allergenic Tryp_alpha_amyl family members in plants have not been fully investigated. In this study, we firstly found two specific motifs beside the common AAI (Alpha-Amylase Inhibitors) domain from the allergenic Tryp_alpha_amyl family members in rice seeds (trRSAs). To understand the evolution and the functional importance of the Tryp_alpha_amy1 family and the specific motifs for allergenic one, we performed BLAST search and identified 75 trHAs (homologous proteins of trRSAs) from 22 plant species including main crops such as rice, maize (Zea mays), wheat (Triticum aestivum) and sorghum (Sorghum bicolor) from all available sequences in the public databases. Statistical analysis showed that the allergenicity of trHAs is closely associated to these two motifs with high number of cysteine residues (p-value = 0.00026), and the trHAs with and without the two motifs were clustered into separate clades, respectively. Furthermore, significant difference was observed on the secondary and tertiary structures between of allergenic and non-allergenic trHAs. In addition, expression analysis showed that trHA-encoding genes of purple false brome (Brachypodium distachyon), barrel medic (Medicago truncatula), rice and sorghum are dominantly expressed in seeds. This work provides insight into the understanding of the properties of allergens in the Tryp_alpha_amyl family and is helpful for allergy therapy.Journal of Agricultural and Food Chemistry 12/2013; 62(1). DOI:10.1021/jf402463w · 3.11 Impact Factor
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ABSTRACT: Allergic reactions to tree nuts are a growing global concern as the number of affected individuals continues to rise. Unlike some food allergies, tree nuts can cause severe reactions that persist throughout life. The tree nuts discussed in this review include those most commonly responsible for allergic reactions: cashew, almond, hazelnut, walnut, pecan, Brazil nut, pistachio, and chestnut. The native allergenic proteins derived from tree nuts are frequently difficult to isolate and purify and may not be adequately represented in aqueous nut protein extracts. Consequently, defined recombinant allergens have become useful reagents in a variety of immunoassays aimed at the diagnosis of tree nut allergy, assessing cross-reactivity between various nuts and other seeds, mapping of IgE binding epitopes, and analyzing the effects of the food matrix, food processing, and gastric digestion on allergenicity. This review describes the approaches that can be used for the production of recombinant tree nut allergens and addresses key issues associated with their production and downstream applications.Methods 07/2013; DOI:10.1016/j.ymeth.2013.07.033 · 3.22 Impact Factor