Diagnostic accuracy of component resolved diagnosis in children with wheat allergy.

Background: Wheat allergy (WA) affects about 0.4-1% of the worldwide population and can occur after ingestion (food allergy), inhalation (baker’s asthma), contact (contact urticaria) or physical exercise after eating wheat-based foods. Among the 21 allergenic components of wheat, gliadins are markers of genuine wheat sensitization and ω-5 gliadin (Tri a 19) is a significant allergen in young children with immediate reactions to ingested wheat. Moreover, the non-specific lipid transfer protein (nsLTP) Tri a 14 is a relevant food allergen in wheat allergic patients from the Mediterranean area and is also associated with baker’s asthma. The aim of this study is to investigate the molecular patterns of wheat sensitization in a pediatric population and to assess the diagnostic accuracy of Tri a 14 and Tri a 19 in predicting IgE-mediated adverse reactions to wheat. Method: For this cross-sectional study, we consecutively enrolled 19 patients (13 males, mean age 8 yrs - range 0,6-17) with sensitization to wheat grain referring to the Pediatric Allergy Outpatient Unit of S. Orsola- Malpighi Hospital of Bologna (Italy) from October 2013 to December 2014. Patients were assessed by SPT and serum sIgE against pollens, wheat, gluten and the molecular allergens rTri a 19 and rTri a 14. The diagnosis of WA was confirmed with open food challenges (OFC). Results: The diagnosis of WA was confirmed in 6/19 patients (32%), of whom 2 (33%) suffered also from grass pollen allergy. The levels of sIgE (geometric mean) to wheat were almost 4 times higher in allergic patients compared to the tolerant ones (35,2 vs.8,2 kU/L). The comparison between the different patterns of sensitization showed among the wheat-allergic group a higher prevalence of sIgE sensitization against gluten (100% vs. 75%), rTri a 14 (50% vs. 46%) and rTri a 19 (83% vs. 0%). The molecular component rTria a19 showed a good sensitivity (83,3%) and specificity (100%) in diagnosing WA, and a PPV and a NPV higher than rTri a 14 (respectively 100% vs. 33,3% and 92,9% vs. 70%). Conclusion: Patients with OFC confirmed WA have different profiles of sensitization than the tolerant ones; in particular the diagnostic accuracy of Tri a 19 is better than rTri a14 in the diagnosis of WA. However these findings need to be confirmed in a larger study population. 1. Palosuo K, Varjonen E, Kekki OM, et al. Wheat omega-5 gliadin is a major allergen in children with immediate allergy to ingested wheat. JACI 2001;108:634-38. 2. Mäkelä MJ, Eriksson C, Kotaniemi-Syrjänen A, et al. Wheat allergy in children - new tools for diagnostics. CEA 2014;44:1420-30