Allergenicity Assessment of Apple Cultivars: Hurdles in Quantifying Labile Fruit Allergens

• Published in: International Archives of Allergy and Immunology 2006-01, Vol.141 (3), p.230-240
• Main Authors: Zuidmeer, L., van Leeuwen, W.A., Kleine Budde, I., Breiteneder, H., Ma, Y., Mills, C., Sancho, A.I., Meulenbroek, E.J., van de Weg, E., Gilissen, L., Ferreira, F., Hoffmann-Sommergruber, K., van Ree, R.
• Format: Article
• Language: English
• Subjects: Allergens - analysis; Allergens - immunology; Antigens, Plant; Apples; Biological and medical sciences; birch pollen allergen; controlled food challenge; cross-reactive structures; Cultivars; double-blind; Food allergies; Fruit - chemistry; Fruit - immunology; Fundamental and applied biological sciences. Psychology; Fundamental immunology; Humans; ige-binding; Immunoassay; Immunoassay - methods; Immunoassay - standards; Immunopathology; in-vivo; lipid transfer protein; major allergens; Malus; Medical sciences; messenger-rna; Original Paper; Plant Extracts - chemistry; Plant Extracts - immunology; Plant Proteins - analysis; Plant Proteins - standards; Species Specificity; vegetable foods
• ISSN: 1018-2438; 1423-0097; 1365-2567
• DOI: 10.1159/000095293

Background: Assessment of allergenicity of foods is important for allergic consumers and regulators. Immunoassays to measure major food allergens are widely applied, often giving variable results. Using the major apple allergen Mal d 1 as a model, we aimed to establish at the molecular level why different immunoassays for assessing allergenicity of apple cultivars produce conflicting outcomes. Methods: Mal d 1 was measured in 53 cultivars from Italy and 35 from The Netherlands, using four different immunoassays. Purified Mal d 1 standards were molecularly characterized by size-exclusion chromatography (SEC) and mass spectrometry (MS). Results: Three immunoassays using an identical standard gave similar results. Minor differences in sample preparation already resulted in significant loss of allergenicity. The fourth assay, using a different Mal d 1 standard, gave 10- to 100-fold lower outcomes. By SEC, this standard was shown to be almost fully aggregated. This aggregation was accompanied by a decrease of the mass of the Mal d 1 molecule by ∼1 kDa as analyzed by MS. The deviating immunoassay was shown to selectively recognize this aggregated form of Mal d 1, whereas the other three assays, including the one based on IgE antibody recognition, preferentially bound non-aggregated allergen. Conclusions: Variable and poorly controllable major allergen modification in both extracts and standards hamper accurate allergenicity assessments of fruits.