Characterization of Buckwheat 19-kD Allergen and Its Application for Diagnosing Clinical Reactivity

• Published in: International archives of allergy and immunology Vol. 144; no. 4; pp. 267 - 274
• Main Authors: Choi, Soo-Young, Sohn, Jung-Ho, Lee, Yong-Won, Lee, Eun-Kyung, Hong, Chein-Soo, Park, Jung-Won
• Format: Journal Article
• Language: English
• Published: Basel, Switzerland Karger 01.01.2007; S. Karger AG
• Subjects: Adolescent; Adult; Allergens - adverse effects; Allergens - genetics; Allergens - immunology; Allergies; Amino Acid Sequence; Anacardium; Antigens, Plant - adverse effects; Antigens, Plant - genetics; Antigens, Plant - immunology; Biological and medical sciences; Child; DNA, Complementary; Double-Blind Method; Escherichia coli; Fagopyrum - chemistry; Fagopyrum - immunology; Female; Food Hypersensitivity - diagnosis; Food Hypersensitivity - immunology; Fundamental and applied biological sciences. Psychology; Fundamental immunology; Grain; Humans; Immunoglobulin E - blood; Immunoglobulin E - immunology; Immunology; Immunopathology; Juglans; Male; Medical diagnosis; Medical sciences; Molecular Sequence Data; Original Paper; Plant Extracts - adverse effects; Plant Extracts - immunology; Plant Proteins - adverse effects; Plant Proteins - genetics; Plant Proteins - immunology; Proteins; Recombinant Proteins - immunology; Sarcoidosis. Granulomatous diseases of unproved etiology. Connective tissue diseases. Elastic tissue diseases. Vasculitis; Sesamum indicum; Skin Tests; Buckwheat allergen; Major allergen; Clinical reactivity; 19-kD allergen; Characterization; Allergy; Immunopathology; Immunology; Reactivity; Buckwheat; Diagnosis; Allergen
• ISSN: 1018-2438; 1423-0097; 1423-0097
• DOI: 10.1159/000106315

Background: The 19-kD protein of buckwheat (BW) has been suggested to be a major allergen, but its characteristics and clinical significance are poorly defined. Methods: cDNA of the 19-kD BW allergen was cloned and expressed in Escherichia coli. Allergenicity and cross-allergenicity were confirmed by inhibition immunoblotting or by ELISA inhibition. The recombinant (r19-kD) protein was assessed for clinical utility in the diagnosis of BW reactivity in 18 BW-allergic and 19 BW-asymptomatic sensitized subjects using receiver operating characteristic analysis. Results: The 19-kD BW allergen, which is composed of 135 amino acids, has a weak homology to the vicilin-like allergens of cashew (Ana o 1), English walnut (Jug r 2) and 7 S globulin from Sesamum indicum. The r19-kD protein can inhibit sIgE binding to native 19-kD BW allergen. The maximum percentage inhibition of sIgE binding to crude BW extract was 56%. About 83.3% of the BW allergy patients had sIgE bound to r19-kD protein, compared to only 1 of the 19 BW-asymptomatic sensitized subjects. The areas under the receiver operating characteristic curves for the skin prick tests [0.925 (95% confidence interval: 0.839–1.012), p < 0.001] as well as r19-kD protein sIgE ELISAs [0.860 (95% confidence interval: 0.725–0.995), p <0.001] were higher than that of BW sIgE coated allergen particle test results [0.803 (95% confidence interval: 0.661–0.945), p = 0.002]. Conclusions: The 19-kD BW allergen may be the major allergen from BW. For the diagnosis of clinical reactivity to BW, the r19-kD protein sIgE ELISA test was more discriminative than the coated allergen particle sIgE measurement using whole BW extract.