Identification of a vicilin-like major allergen from Prosopis juliflora exhibiting cross- reactivity with legume food allergens. (September 2021)

• Record Type: Journal Article
• Authors: Arora, Bharti; Sharma, Swati; Gaur, S.N.; Jain, Vikram K.; Lavasa, Shakuntala; Arora, Naveen
• Is Part Of: Molecular immunology. Volume 137(2021)
• Page Start: 84
• Page End: 93
• Publication Date: 2021-09
• Subjects: Prosopis juliflora -- Glycoprotein -- Cross-reactivity -- Legumes; Immunochemistry -- Periodicals; Molecular biology -- Periodicals; Immunochemistry -- Periodicals; Allergy and Immunology -- Periodicals; Molecular Biology -- Periodicals; Immunochimie -- Périodiques; Biologie moléculaire -- Périodiques; Immunochemistry; Molecular biology; Periodicals; Electronic journals; 571.96
• DOI: 10.1016/j.molimm.2021.06.023
• Languages: English
• ISSNs: 0161-5890

Abstract

Highlights: A 35 kDa major allergen is purified from pollen of Prosopis juliflora, exhibits 75% IgE reactivity in ELISA and immunoblot. The purified allergen is a glycoprotein with terminal mannose and glucose residues. The glycan moiety of protein is partially responsible for its allergenicity and functional activity (basophil activation). The purified allergen shows sequence homology with Lup an 1(β conglutin) of lupin bean. The purified allergen exhibits significant cross-reactivity with common edible legumes. Abstract: Background: Prosopis juliflora is a clinically relevant allergic sensitizer worldwide and shares cross-reactivity with allergens from several tree pollen and food. The present study aims to purify and immunobiochemically characterize a major allergen from Prosopis pollen. The allergen was further investigated for its cross-reactivity with legume allergens. Methods: Prosopis extract was fractionated by Q Sepharose and Superdex 75 gel filtration column to purify the allergen. Specific IgE against purified protein was estimated via ELISA and immunoblot. The protein was subjected to mass spectrometric analysis. Glycan characterization was performed by Schiff staining and lectin binding assay followed by deglycosylation studies. The functional activity of the purified protein was evaluated by the basophil activation test. Cross-reactivity was assessed by inhibition studies with legume extracts. Results: A 35 kDa protein was purified and showed 75% IgE reactivity with the patients' sera by ELISA and immunoblot. Glycan characterization of protein demonstrated the presence of terminal glucose and mannose residues. A reduction of 40% and 27% in IgE binding was observed upon chemical and enzymatic deglycosylation of the protein, respectively. The glycoprotein allergen upregulates the expression of CD203c on basophils which was significantly reduced upon deglycosylation, signifying its biological ability to activate the effector cells. The identified protein shared significant homology with Lup an 1 from the lupine bean. Immunoblot inhibition studies of the purified allergen with legume extracts underlined high cross-reactive potential. Complete inhibition was observed with peanut and common bean, while up to 70% inhibition was demonstrated with soy, black gram, chickpea, and lima bean. Conclusion: A 35 kDa vicilin-like major allergen was isolated from P. juliflora . The protein possesses glycan moieties crucial for IgE binding and basophil activation. Furthermore, the purified protein shows homology with Lup an 1 and exhibits cross-reactivity with common edible legume proteins.