Identification of Critical Amino Acids in the IgE Epitopes of Ric c 1 and Ric c 3 and the Application of Glutamic Acid as an IgE Blocker

Natalia Deus-De-Oliveira,Olga L T Machado,Renato Augusto Damatta,Keysson V Fernandes,Camila Carrielo-Gama,Shayany P Felix,Jean Kanellopoulos

doi:10.1371/journal.pone.0021455

Natalia Deus-De-Oliveira, Olga L T Machado + Show 5 more

Open Access

https://doi.org/10.1371/journal.pone.0021455

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Journal: PloS one	Publication Date: Jun 27, 2011
Citations: 32	License type: CC BY 4.0

Affiliation: State University of Norte Fluminense

Abstract

BackgroundThe allergenicity of Ricinus communis L. (castor bean, Euphorbiaceae) is associated with components of its seeds and pollen. Castor bean allergy has been described not only in laboratory workers, but also in personnel working in oil processing mills, fertilizer retail, the upholstery industry and other industrial fields. In the present study, we describe the critical amino acids in the IgE-binding epitopes in Ric c 1 and Ric c 3, two major allergens of R. communis. In addition, we also investigate the cross-reactivity between castor bean and some air and food allergen extracts commonly used in allergy diagnosis.Methodology/Principal FindingsThe IgE reactivity of human sera from atopic patients was screened by immune-dot blot against castor bean allergens. Allergenic activity was evaluated in vitro using a rat mast cell activation assay and by ELISA. Cross-reactivity was observed between castor bean allergens and extracts from shrimp, fish, gluten, wheat, soybean, peanut, corn, house dust, tobacco and airborne fungal allergens. We observed that treatment of rat and human sera (from atopic patients) with glutamic acid reduced the IgE-epitope interaction.Conclusions/SignificanceThe identification of glutamic acid residues with critical roles in IgE-binding to Ric c 3 and Ric c 1 support the potential use of free amino acids in allergy treatment.

Highlights

Castor bean (Ricinus communis L.) contains approximately 50% oil, which has special characteristics such as a high viscosity, a high stability under heat and pressure, a low freezing point, and the ability to form waxy substances upon chemical treatment
We have recently reported the identification of IgE-binding epitopes of castor bean seed allergens, defining four continuous epitopes in Ric c 3 and two in Ric c 1 [12]
To verify that these residues are essential for IgE binding, we examined mast cells incubated with IgE in the presence of synthetic peptides modified by Woodward’s Reagent K

Summary

Introduction

Castor bean (Ricinus communis L.) contains approximately 50% oil, which has special characteristics such as a high viscosity, a high stability under heat and pressure, a low freezing point, and the ability to form waxy substances upon chemical treatment. Major castor bean allergens were identified [7,8,9,10,11]. We have recently reported the identification of IgE-binding epitopes of castor bean seed allergens, defining four continuous epitopes in Ric c 3 and two in Ric c 1 [12]. (castor bean, Euphorbiaceae) is associated with components of its seeds and pollen. We describe the critical amino acids in the IgE-binding epitopes in Ric c 1 and Ric c 3, two major allergens of R. communis. We investigate the cross-reactivity between castor bean and some air and food allergen extracts commonly used in allergy diagnosis

Methods

Results

Conclusion