Induction of Allergic Responses to Peanut Allergen in Sheep

Jenna L Van Gramberg,Robert J Bischof,Els N T Meeusen,Michael J De Veer,Robyn E O'Hehir,Marco Idzko

doi:10.1371/journal.pone.0051386

Abstract

Peanut allergy is the leading cause of deaths due to food-induced anaphylaxis but despite continued research, there are currently no specific treatments available. Challenge testing is limited in patients due to the high risk of adverse reactions, emphasising the need for an appropriate animal model. In the present study we examine the induction of allergic responses in a sheep model for peanut allergy. Sheep were sensitised with peanut (PN) extract and in separate injections with ovalbumin (OVA) or house dust mite (HDM) extract. Serum PN-specific IgE responses were detected in 40–50% of immunised sheep, while only 10% (1 of 10 sheep) showed detectable OVA-specific IgE. All PN-allergic sheep tested showed an Ara h 1-specific IgE response, while four out of five allergic sheep showed an Ara h 2-specific IgE response. Animals with high serum IgE levels to HDM were also PN IgE-positive. Of the PN-sensitised animals with high PN-specific IgE, 80% also showed an immediate hypersensitivity reaction following an intradermal PN injection. This new large animal model of peanut allergy may provide a useful tool for future investigations of allergen-associated immune mechanisms and specific immunotherapy.

Highlights

‘Food allergy’ can be described as an exaggerated immune response to certain ingredients present in food and characterised by the production of immunoglobulin E (IgE) antibodies [1,2]
Experimental sheep and allergen sensitisations All experimental animal procedures and the collection of tissues and cells were approved by the Animal Experimental Ethics Committee of Monash University, following guidelines set by the National Health and Medical Research Council (NH&MRC) of Australia
In the present study we report the induction of allergic responses to peanut (PN) allergen in sheep, whereby sensitisation with a crude extract of PN induced high levels of PN-specific IgE in 40– 50% of animals

Summary

Introduction

‘Food allergy’ can be described as an exaggerated immune response to certain ingredients present in food and characterised by the production of immunoglobulin E (IgE) antibodies [1,2] These IgE antibodies have been shown to have high affinity to receptors on immune cells such as mast cells and basophils [3] and interactions with these cells can lead to the release of potent mediators and the development of allergy symptoms [4,5]. We have previously established a sheep model of allergic asthma based on house dust mite (HDM), that represents many features of the human disease including allergen-specific IgE responses, local and systemic inflammation and remodelling of the airways [26,27]. The aim of the present study was to examine the induction of allergic responses to crude peanut allergens in sheep and establish the potential for this model in future studies of peanut allergy predisposition

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