Yuji Mori

BACKGROUND: Buckwheat allergy carries a high risk of anaphylaxis. Although the oral food challenge (OFC) is the diagnostic gold standard, it can provoke severe reactions, leading many patients to adopt elimination diets. Conventional markers, including buckwheat-specific IgE (Bw-sIgE) and skin prick testing, have limited accuracy. The IgE crosslinking-induced luciferase expression (EXiLE) assay is a serum-based in vitro cell-activation test that has shown high accuracy for other food allergies. We evaluated its utility for buckwheat allergy. METHODS: This multicenter observational study in Japan enrolled participants with buckwheat-specific IgE ≥ 0.35 UA/mL (n = 25), categorized as buckwheat allergy (BwA) or non-buckwheat allergy (non-BwA) based on OFC results. The EXiLE assay used crude buckwheat antigen at 0.1-1000 ng/mL. Diagnostic performance was compared using receiver operating characteristic (ROC) curves for EXiLE, Bw-sIgE, and the Bw-sIgE/total IgE ratio. RESULTS: Among 25 participants, the EXiLE assay demonstrated superior diagnostic performance compared to Bw-sIgE and the Bw-sIgE/total IgE ratio. The area under the ROC curve (AUC) was 0.96 at 10 ng/mL (1 ng/mL, 0.94), exceeding Bw-sIgE (0.68) and the Bw-sIgE/total IgE ratio (0.72). At optimal cutoffs, EXiLE achieved sensitivity 0.92, specificity 0.92, and LR+ 11.1 (versus LR+ 3.2 for Bw-sIgE and 2.5 for the IgE ratio), indicating fewer false positives and better overall accuracy. CONCLUSION: The EXiLE assay provides high diagnostic accuracy for IgE-mediated buckwheat allergy and, as a serum-based in vitro assay, may reduce reliance on OFC and help avoid unnecessary elimination diets.

Patients with peach allergy who experience severe symptoms, including anaphylaxis, reportedly have a higher positivity for peach gibberellin-regulated protein (GRP)-specific immunoglobulin (Ig) E than those with only oral symptoms. However, a study in Italy investigating apple allergy (another Rosaceae fruit) found no clear association between apple GRP-specific IgE levels and clinical disease types. This study aimed to evaluate the clinical utility of GRP-specific IgE measurement in Japanese patients with apple allergy. We collected sera from apple-allergic patients in Japan and measured their IgE levels specific to apple GRP. Apple-allergic patients (14 with oral reactions and 14 with systemic reactions) and seven non-allergic controls were examined. The specific IgE levels against apple, Mal d 1, Mal d 4, Japanese cedar, Japanese alder, Japanese white birch, Bet v 1, and Bet v 2 were also determined using 3gAllergy™. Positive results for apple-GRP-specific IgE by enzyme-linked immunosorbent assay were obtained in one patient with oral reactions and in seven cases of systemic reactions. Exercise as a cofactor was involved in cases with high apple GRP-specific IgE. GRP expression was considerably lower in apples than in peaches, as detected by reverse transcription-quantitative polymerase chain reaction testing. Thus, GRP-specific IgE may be an important marker for diagnosing systemic reactions triggered by exercise in fruits with low GRP expression, such as apples.

BACKGROUND: Walnut (Juglans regia) frequently triggers nut allergies in the United Kingdom and in the United States, with increasing cases in Japan. While oral food challenges (OFCs) are the definitive method for diagnosing these allergies, they pose the risk of symptom provocation, necessitating safer alternative tests. Our aim here was to evaluate the diagnostic utility of IgE (immunoglobulin E) crosslinking-induced luciferase expression (EXiLE) for walnut allergy compared with the walnut-specific IgE (sIgE) test, Jug r 1-sIgE test, and skin prick test (SPT). METHODS: This retrospective study analyzed 55 patients tested for walnut allergy (WA) at Fujita Health University Bantane Hospital from January 2021 to December 2023. Among them, 38 had allergic reactions to walnuts based on history or OFCs and 17 did not. We evaluated the sensitivity, specificity, positive predictive value, negative predictive value, and the area under the curve (AUC) of the receiver operating characteristic curve. RESULTS: The EXiLE method (AUC = 0.938) exhibited superior diagnostic accuracy compared to the walnut-sIgE and comparable performance to Jug r 1-sIgE and SPT. The optimal cutoff value of 1.26-fold change demonstrated high sensitivity (0.92), specificity (0.88), positive predictive value (0.92), and negative predictive value (0.82). The EXiLE method yielded positive results in all three cases with negative Jug r 1-sIgE (< 0.35 UA/mL). CONCLUSION: The EXiLE method showed high sensitivity and specificity for diagnosing WA, indicating its potential clinical utility. Furthermore, the combination of Jug r 1-sIgE and EXiLE may enhance diagnostic accuracy. Future large-scale studies are warranted to confirm these findings and establish comprehensive diagnostic protocols.