Children Suspected for Hazelnut Allergy with and without Concomitant Peanut Allergy Have 4 Independent and Well Characterized Serotypes.
Sunday, March 6, 2016
South Exhibit Hall H (Convention Center)
Esben Eller, MSc. PhD, Charlotte G Mortz, MD, Phd, Carsten Bindslev-Jensen, MD PhD DMSci FAAAAI
Rationale: Hazelnut is the most frequent cause of tree-nut allergy, but up to half of all hazelnut allergic patients also have allergy to peanut. This, combined with cross-reactivity between birch, hazelnut and peanut allergens blur the serological picture.  We therefore aimed to identify distinct serotypes, based on Component-Resolved-Diagnostics (CRD), in patients suspected for hazelnut allergy with and without concomitant peanut allergy.

Methods:  We included 155 children suspected for hazelnut allergy and subsequently challenged them according to guidelines. Concomitant allergy to peanuts was also verified or ruled out by challenge. Skin Prick Test, Specific-IgE and CRD to hazelnut, peanut, PR10 and LPT protein families were measured with ImmunoCap.

Results: Sixty-five children had a positive hazelnut challenge, and 60% of these also had concomitant peanut allergy. Children allergic to hazelnut were mainly sensitized to Cor a 9 and Cor a 14, peanut allergic children primarily to Ara h 2. Sensitization to PR10 proteins components were seen in 30-45% of all included children, irrelevant of allergies to peanut or hazelnut. A cutoff > 0.72 kU/L of IgE towards Cor a 14 diagnosed 87% correctly, making Cor a 14 the superior serology marker.

Conclusions: We found 4 independent and well characterized serotypes; Hazelnut allergic children sensitized primarily to Cor a 14 and peanut allergic children sensitized primarily to Ara h 2. Patients with allergy to both were sensitized to both. The forth group, negative in challenge to both peanut and hazelnut, was primarily sensitized to PR10 proteins.