Safety of Low Dose Wheat Oral Food Challenges in Cases with Low ?-5 Gliadin-Specific IgE Levels.

BACKGROUND: Oral food challenge test (OFC) is essential for the diagnosis and management of wheat allergy. In individuals considered to be at low risk, OFCs may be performed even in general clinical settings. Although ω-5 gliadin-specific IgE (sIgE) is associated with immediate allergic reactions to wheat, the safety of OFCs in cases with low ω-5 gliadin-sIgE levels has not been well investigated. We evaluated the safety of wheat OFCs in cases with ω-5 gliadin-sIgE levels < 3.5 kU/L. METHODS: We retrospectively analyzed wheat OFCs performed at two hospitals between 2017 and 2021. 337 cases with ω-5 gliadin-sIgE levels < 3.5 kU/L were included. These cases were further classified according to Wheat-sIgE levels: Wheat-sIgE < 3.5 kU/L (Low Wheat-sIgE [LW-sIgE] group; 115 cases) vs ≥ 3.5 kU/L (High Wheat-sIgE [HW-sIgE] group; 222 cases). The OFC-positive rate and its association with the challenge dose were evaluated. RESULTS: A total of 337 cases with ω-5 gliadin-sIgE levels (< 3.5 kU/L) were included. The OFC-positive rate was comparable between the LW-sIgE group (22.6%) and the HW-sIgE group (23.0%). Anaphylaxis occurred in six cases (1.8%); however, none required intramuscular adrenaline administration. In low-dose OFC (≤ 2 g of udon; ≤ 52 mg of wheat protein), more than 90% of cases in both groups were negative. Cases with positive low-dose OFC results had higher ω-5 gliadin-sIgE levels and a higher rate of complete wheat elimination. CONCLUSION: Wheat OFCs can be performed relatively safely in cases with low ω-5 gliadin-sIgE levels. Initiating OFCs at a low dose may improve their safety.