Impact of thermal processing and the Maillard reaction on the basophil activation of hazelnut allergic patients Tatiana Cucu a,b , Bruno De Meulenaer a , Chris Bridts c , Bart Devreese b , Didier Ebo c,⇑ a Department of Food Safety and Food Quality, Research Group Food Chemistry and Human Nutrition, Ghent University, Coupure Links 653, B-9000 Gent, Belgium b Laboratory for Protein Biochemistry and Biomolecular Engineering, Ghent University, K.L. Ledeganckstraat 35, B-9000 Gent, Belgium c Faculty of Medicine, Department of Immunology – Allergology – Rheumatology, University of Antwerp, Campus Drie Eiken T4.08, Universiteitsplein 1, B-2610 Antwerp, Belgium article info Article history: Received 12 January 2012 Accepted 22 February 2012 Available online 3 March 2012 Keywords: Basophil activation test Food allergy Hazelnut (Corylus avellana) Maillard reaction Oral allergy syndrome Systemic allergic reactions abstract Food allergy, an abnormal immunological response due to sensitization to a food component, has become an important health problem, especially in industrialized countries. The aim of this study was to inves- tigate the impact of thermal processing and glycation on the basophil activation by hazelnut proteins using a basophil activation test. Patients with systemic allergic reactions (SR; n = 6) to hazelnut as well as patients with an isolated oral allergy syndrome (OAS; n = 4) were investigated. Thermal processing of hazelnut proteins either in the presence or absence of wheat proteins did not result in major changes in the stimulatory activity of the basophils for patients with SR or OAS. For the patients with OAS, incu- bation of hazelnut proteins with glucose led to complete depletion of the stimulatory activity of the baso- phils. An increase in stimulatory activity of the basophils for two out of six patients with SR was observed. For the other four patients slight or complete abolition of the stimulatory activity was observed. These results indicate that some patients with SR to hazelnut are at risk when exposed to hazelnut proteins, even in processed foods. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Food allergy, an abnormal immunological response due to sen- sitization to a food component, has become an important health problem, especially in industrialized countries. It is estimated that IgE mediated food allergy affects about 2% of the adult population and up to 8% of the children (Monaci et al., 2006). However, the prevalence of sensitization is much higher (patients with specific IgE to certain foods without manifesting clinical allergy) and in Belgium it represents about 6% for hazelnut (Burney et al., 2010). The symptoms manifested upon inadvertent ingestion of hazelnuts can vary from a mild oral allergy syndrome (OAS) (Hirschwehr et al., 1993; Luttkopf et al., 2002) to more severe anaphylactic reac- tions (Hansen et al., 2009; Schocker et al., 2004). Hazelnuts (Cory- lus avellana) are widely used nowadays in the food industry, especially in confectionary products. The European Commission Directive 2007/68/EC proposed hazelnut containing foods to be la- beled regardless of the amount present (European Parliament and Council, 2007). However, foods may be unintentionally contami- nated via allergen-containing ingredients or carry-over during pro- cessing, posing a serious threat to allergic consumers. In a previous study, we have shown that modifications of hazel- nut proteins through reactions typically occurring during food processing, lead to significant changes in the detectability of hazelnut proteins by the commercial kits leading to especially false negative results (Cucu et al., 2011). This indicates that food products de- clared free of hazelnut allergens by the commercial kits could still affect the allergic consumers. However, it is not known yet whether changes in the triggering effect of the effector cells in- volved in the IgE-mediated allergies should be expected as well. Abundant evidence exists on how thermal processing and Maillard reaction can greatly influence the IgE binding activity of some food components (Gruber et al., 2004, 2005; Nakamura et al., 2005, 2008). Decreases but also increases of the IgE binding activity were observed, without clear trends being established. It was previously shown that roasting of hazelnut can lead to a reduction of the aller- genicity nevertheless exceptions in some patients were observed (Muller et al., 2000; Pastorello et al., 2002; Schocker et al., 2000; Wigotzki et al., 2001; Worm et al., 2009). Remarkably, most of the patients considered for the study of the impact of roasting on the allergenicity were patients with OAS. It is reported that pa- tients with OAS are mostly allergic to the labile pollen related hazelnut allergens such as Cor a 1 and/or Cor a 2 (Worm et al., 2009). It is therefore not surprising that thermal processing as well as glycation lead to severe or complete reduction of the allergen- icity of roasted hazelnuts. For the patients with systemic reactions, known to react to components resistant to heat treatment and digestion (Cor a 8, Cor a 9 and Cor a 11) lesser effect were observed (Dooper et al., 2008; Muller et al., 2000; Pastorello et al., 2002). 0278-6915/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.fct.2012.02.069 ⇑ Corresponding author. Tel.: +32 (0) 3 2652595; fax: +32 (0) 3 2652655. E-mail address: didier.ebo@ua.ac.be (D. Ebo). Food and Chemical Toxicology 50 (2012) 1722–1728 Contents lists available at SciVerse ScienceDirect Food and Chemical Toxicology journal homepage: www.elsevier.com/locate/foodchemtox