The Severity and Frequency of Systemic Reactions to Hazelnut Are Significantly Higher in Hazelnut Allergic Patients Monosensitized to <i>Cor a 8</i> than in Patients Polysensitized to <i>Cor a 1</i>, <i>Cor a 8</i>, and <i>Cor a 9</i>

Abstract

<b><i>Introduction:</i></b> Hazelnuts are a leading trigger of food allergy. To date, several molecular components of hazelnut are available for component-resolved diagnosis. However, little is known about how simultaneous sensitization to multiple allergens affects the severity of the hazelnut-induced reaction. In a previous study, our group demonstrated a lower risk of systemic reactions to peach in patients sensitized to both <i>Pru p 3</i> and <i>Pru p 1</i> than in the patient monosensitized to peach LTP. We aimed to assess whether this was also true in hazelnut allergy in a cohort of adult patients. <b><i>Methods:</i></b> Patients were selected based on a history of symptoms such as urticaria, vomiting, diarrhea, asthma, and anaphylaxis indicative of hazelnut IgE-mediated food allergy and graded according to a clinical severity scale. For all patients, specific IgE was determined for <i>Cor a 1</i> and <i>Cor a 8</i> and, for most patients, also <i>Cor a 9</i>. Patients were offered an oral food challenge in open format (OFC) with a cocoa-based roasted hazelnut spread on a voluntary basis in order to prescribe an appropriate diet. <b><i>Results:</i></b> A total of two hundred and fourteen patients were recruited. Among these, 43 patients were monosensitized to <i>Cor a 8</i>. One hundred and seventy-one patients were sensitized to <i>Cor a 1</i> (79.9%), and, among them, 48/171 (28.1%) were also <i>Cor a 8</i> positive. <i>Cor a 9</i> was evaluated in 124/214 patients, testing positive in 21/124 (16.9%). Patients monosensitized to <i>Cor a 8</i> experienced systemic reactions more frequently than those sensitized to <i>Cor a 1</i> ± <i>Cor a 8</i> (<i>p</i> &lt; 0.00001), with significantly more severe reactions (<i>p</i> &lt; 0.0005) and testing more frequently positive at OFC (<i>p</i> &lt; 0.0001). Regarding <i>Cor a</i> 9, the sensitized patients were significantly younger (<i>p</i> = 0.0013) and showed reactions of similar severity to patients who tested <i>Cor a 9</i> negative, and these reactions were milder than in patients monosensitized only to <i>Cor a</i> 8. <b><i>Discussion/Conclusion:</i></b> Sensitization to <i>Cor a 1</i> seems to protect from the development of the severe systemic reactions induced by <i>Cor a</i> 8 sensitization, <i>Cor a 9</i> does not influence the severity of symptoms in adult patients. The OFC with roasted hazelnut may help in dietary guidance.