Utility of Specific IgE to Ara h 2 in Italian Allergic and Tolerant Children Sensitized to Peanut

Emerging data suggest that measurement of serum IgE to peanut components can be clinically helpful and more accurate than IgE to whole peanut to predict peanut allergy. Not all studies have used prospective samples, multiple components and oral challenges. Currently, there are no data on this topic involving Italian children. 32 patients (23 males; median age 9 years) with reported history for peanut allergy and evidence of peanut sensitization (skin prick test to peanut extract  3mm) have been analyzed for serum IgE to whole peanut and recombinant allergen components Ara h 1, 2, 3, 8, and 9 with Immuno CAP and completed an open oral food challenge with peanut. 12 (37.5%) children had a positive challenge to peanut and were considered allergic. No differences were seen between the median values of IgE to peanut, Ara h 1, 3, 8 and 9 in allergic and tolerant children to peanut challenge. Noteworthy, 5 of 20 tolerant children had IgE to peanut> 15 kUA/l which is commonly considered a predictive value of peanut allergy. Conversely, a significant difference was seen when comparing the median value of IgE to Ara h 2 in the two groups: 0.75 kUA/l (IQR: 0.22-4.34 kUA/l) in allergic children versus 0.1 kUA/l (IQR: 0.1-0.12 kUA/l) in tolerant ones (P< 0.001). IgE levels to Ara h 2 are significantly higher in children that react to oral peanut challenge. Our findings in Italian children have been in line with recent reports in various populations of Northern Europe, the US and Australia and add confirmatory evidence that analysis of IgE to Ara h 2 could reduce the need for peanut challenge in suspected allergic patients