Abstract
BackgroundSensitization to hazelnut allergens vary depending on the geographic origin and age of the patients. The objective of this study was to further investigate the allergenic activity of hazelnut allergens using sera from patients recruited in various European regions and presenting different sensitization patterns to hazelnut proteins.MethodsNatural Cor a 11 and Cor a 9 were purified from hazelnut whereas Cor a 1 and Cor a 8 were produced as recombinant proteins (rCor a 1.04 and rCor a 8). Sera from hazelnut allergic patients were collected in France (n = 5), Switzerland (n = 2), Greece (n = 11) and Spain (n = 3), within the Europrevall project. Total and allergen-specific IgE were quantified by enzyme allergosorbent test and IgE immunoblot were performed using pooled sera from birch-pollen endemic region or from Greece. Histamine Release (HR) assays were performed with stripped basophils passively sensitized with individual sera and challenged by a hazelnut extract or the different hazelnut allergens.ResultsAs previously described, hazelnut allergic patients from Mediterranean countries are mainly sensitized to the nsLTP Cor a 8 whereas patients from France and Switzerland are sensitized to pollen-related allergens. Interestingly, an intermediate profile was evidenced in patients from Madrid. Hazelnut 7S globulin (Cor a 11) and 11S globulin (Cor a 9) were found to be minor allergens, recognized only by patients from Mediterranean countries. The biologic activity of the 4 tested allergens, analysed by HR assay, further confirmed the sensitization patterns, but also demonstrated the very high elicitation potency of Cor a 8.ConclusionsThis work, extending previously published researches, represents a step towards the better understanding of the complexity of hazelnut allergy and provides new data on the biological activity of hazelnut allergens and extracts.Electronic supplementary materialThe online version of this article (doi:10.1186/s13601-015-0066-7) contains supplementary material, which is available to authorized users.
Highlights
Sensitization to hazelnut allergens vary depending on the geographic origin and age of the patients
IgE sensitization to hazelnut combined both IgE recognition of allergens cross reacting with pollen allergens of the PR-10 family, i.e., Bet v 1-related (Cor a 1), and profilin (Cor a 2), and true food allergens such as the non-specific Lipid Transfer Protein (LTP) Cor a 8 and the seed storage proteins Cor a 9 (11S globulin), Cor a 11 (7S globulin) and Cor a 14 (2S albumin)
Using purified allergens and ImmunoCAP, the IgE concentrations against rCor a 1 were demonstrated to be far higher than that against rCor a 2 [2, 8], but our study suggests that the contents and/or the allergenic activity [21] of the relative allergens within the hazelnut extract have to be taken into consideration to further assess their relative contribution in hazelnut allergy
Summary
Sensitization to hazelnut allergens vary depending on the geographic origin and age of the patients. Prevalence was variable between centers, Blanc et al Clinical and Translational Allergy (2015) 5:26 more severe reactions such as urticaria, angiodaema or anaphylaxis Those symptoms are evidenced in “true food allergic” patients [4, 5]. Sensitization to Cor a 8 purified from hazelnut was evidenced in children from birch-endemic area, i.e., the Netherlands, in which it was associated to more severe allergic reaction upon challenge [9] This was not confirmed in a later study using recombinant Cor a 8 (rCor a 8), suggesting a contamination of the natural Cor a 8 by other seed storage proteins [6, 8, 10]
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