A potential role of gliadin extract skin prick test in IgE-mediated wheat allergy
Thunyatorn Phisitbuntoon,1 Orathai Jirapongsananuruk,1 Punchama Pacharn,1 Unchalee Wangthan,1 Witchaya Srisuwatchari,1 Onrapak Reamtong,2 Nualanong Visitsunthorn,1 Surapon Piboonpocanun3
Affiliations:
1 Division of Allergy and Immunology, Department of Pediatrics, Faculty of Medicines Siriraj Hospital, Mahidol University, Bangkok, Thailand
2 Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
3 Institute of Molecular Biosciences, Mahidol University, Salaya, Nakhonpathom, Thailand
Abstract
Background: Wheat extracts containing both water/salt and alcohol soluble proteins may increase extract’s accuracy for diagnosing IgE-mediated wheat allergy.
Objective: This study aimed to determine the performance of new invented in-house prepared wheat extracts for skin prick test (SPT).
Methods: Children aged 1-18 years with history of immediate wheat allergy were recruited. Four in-house prepared wheat extracts (wheat-Coca-10%EtOH, and 3 new invented extracts, wheat-salt, gliadin, and glutenin) and a commercial wheat extract were used for SPT. Serum specific IgE (sIgE) to wheat and omega-5 (ω-5) gliadin were also determined. Oral food challenge (OFC) with wheat flours was performed in all patients except those with history of wheat-induced anaphylaxis or with recent symptoms within the past 6 months.
Results: Thirty-one children were recruited. Of those, 14 were excluded from OFC (12 with history of anaphylaxis and 2 with recent symptom). OFC was positive in 8 of 17 children. Of the 5 extracts and sIgE to wheat and ω-5 gliadin, gliadin extract provided the best SPT performance with 84.2% sensitivity, 88.9% specificity, 94.1% positive predictive value (PPV), 72.7% negative predictive value (NPV), 7.59 positive likelihood ratio (LR), 0.18 negative LR, and 85.7% accuracy.
Conclusion: Compared to other in-house and commercial wheat extracts and sIgE to wheat and ω-5 gliadin, SPT with an in-house gliadin extract yielded the highest performance for the diagnosis IgE-mediated wheat allergy.
Key words: Gliadin, Glutenin, Oral Food Challenge, Skin Prick Test, Specific IgE to ω-5 gliadin