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Skin prick testing is widely used to predict the presence of allergen-specific IgE. In eosinophilic esophagitis patients, who frequently exhibit polysensitization and broad reactivity upon skin prick testing, this is commonly used to aid avoidance recommendations in the clinical management of their disease. We present here the predictive value of skin prick testing for the presence of allergen-specific IgE, in 12 patients, determined by immunoblot against the allergen extracts using individual-matched serum. Our results demonstrate a high degree of predictive value for aeroallergens but a poor predictive value for food allergens. This suggests that skin prick testing likely identifies IgE reactivity towards aeroallergens in adult eosinophilic esophagitis but this is not true for foods. Consequently, IgE immunoblotting might be required for determining food avoidance in these patients.

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Food allergies are caused by immune responses to food proteins and represent a breakdown of oral tolerance. They can range from mild pruritis to life-threatening anaphylaxis. The only current consensus for treatment is food avoidance, which is fraught with compliance issues. For this reason, there has been recent interest in immunotherapy, which may induce desensitization and possibly even tolerance. Through these effects, immunotherapy may decrease the potential for adverse serious reactions with accidental ingestions while potentially leading to an overall health benefit. In this review, we discuss the mechanisms of food allergy and give an overview of the various immunotherapeutic options and current supporting evidence, as well as look towards the future of potential novel therapeutic modalities. Keywords food allergy; food hypersensitivity; immunotherapy; oral immunotherapy; sublingual immunotherapy Food allergy: epidemiologyFood hypersensitivity reactions have become an increasingly burdensome issue over the last few decades; not only does the prevalence appear to have risen, but the impact on healthcare systems has also become more substantial [1,2]. Data taken from the National Electronic Injury Surveillance System (NEISS) using data from US emergency rooms indicate that there are an estimated 121,000 emergency department visits per year for food allergy-related symptoms, with approximately 3100 hospitalizations. It has been suggested that only slightly over half of the patients with probable anaphylaxis may be correctly coded when entering the hospital, implying that food allergy may be even more common than currently thought [3].Food allergy affects 3.9% of children in the USA, with an approximate 18% increase in the past 10 years [1]. A population-based study using a US FDA questionnaire estimated the prevalence of self-reported food allergy in adults as 9.1%, with 5.3% having a doctor-diagnosed allergy [4]. While in some emergency room studies shellfish has been described as the most common allergen involved in food hypersensitivity in patients over 6 years of age, another meta-analysis noted that milk, egg, peanuts and nuts were more common in the general population [3]. Reactions to food allergens cover a wide clinical spectrum, from mild pruritis to life-threatening anaphylaxis. Although it is true that some types of hypersensitivity fade when children move to adulthood (commonly seen in cases of hen's egg and cow's milk allergies) peanut allergies tend to be persistent and are more commonly life-threatening.