Purification and Characterization of a Major Cross-Reactive Allergen from Epicoccum purpurascens

• Published in: International archives of allergy and immunology Vol. 133; no. 3; pp. 217 - 224
• Main Authors: Bisht, Vandana, Arora, Naveen, Singh, B.P., Gaur, S.N., Sridhara, Susheela
• Format: Journal Article
• Language: English
• Published: Basel, Switzerland Karger 01.03.2004
• Subjects: Allergens - immunology; Allergens - isolation & purification; Alternaria alternata; Ascomycota - chemistry; Ascomycota - immunology; Aspergillus fumigatus; Biological and medical sciences; Blotting, Western; Chromatography, Agarose; Cladosporium herbarum; Cross Reactions - immunology; Curvularia lunata; Electrophoresis, Polyacrylamide Gel; Endopeptidases - metabolism; Enzyme-Linked Immunosorbent Assay; Epicoccum purpurascens; Fundamental and applied biological sciences. Psychology; Fundamental immunology; Fungal Proteins - immunology; Fungal Proteins - isolation & purification; Fusarium solani; Glycoproteins - immunology; Glycoproteins - isolation & purification; Humans; Immunoblotting; Immunoglobulin E - immunology; Immunopathology; Medical sciences; Molecular Weight; Original Paper; Periodic Acid - chemistry; Skin Tests; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Epicoccum nigrum; Purification; Electro-elution; Periodate; Cross-reactivity; Glycoprotein; Epicoccum purpurascens; Allergen; Allergy; Immunopathology; Elution; Periodates; Immunology; Cross reaction
• ISSN: 1018-2438; 1423-0097
• DOI: 10.1159/000076827

Background:Epicoccum purpurascens (formerly nigrum) (EP), is a ubiquitous saprophytic mould found both indoors and outdoors. Several studies have reported sensitization to EP in 5–7 % of different populations worldwide. The diagnosis of mould allergy requires a standardized fungal extract that contains all its important allergenic proteins. The crude allergen extract from EP was standardized earlier, however none of its allergens have been purified. Methods: A major allergen from spore-mycelia extract of EP was purified using concanavalin A (Con A) Sepharose chromatography, gel filtration and electro-elution. The allergen isolated was characterized for its IgE-binding ability and cross-reactivity with five well-known allergenic fungi by ELISA and immunoblot. Results: A 33.5-kD glycoprotein allergen of EP, Epi p 1, was purified to homogeneity. All the EP allergic patients’ sera tested recognized this protein. Periodate modification of Epi p 1 showed partial loss in IgE binding while proteinase K treatment caused complete loss in binding to IgE. Dose-dependent inhibition in binding of rabbit anti Epi p 1 antibodies was obtained with Epi p 1, Aspergillus fumigatus, Alternaria alternata, Curvularia lunata, Cladosporium herbarum and Fusarium solani in ELISA. Rabbit antibodies to all the above five fungi recognized Epi p 1 in immunoblot, confirming that Epi p 1 shares common epitopes with the fungi tested. Conclusion: A major glycoprotein allergen of 33.5 kD was purified from EP which cross-reacts with other fungi. Hence this glycoprotein can be exploited to reduce the panel of allergen extracts used for therapy of mould allergy.