The component-specific to total IgE ratios do not improve peanut and hazelnut allergy diagnoses.

BACKGROUND: Specific IgE measurement predicts the outcome of oral food challenges with considerable uncertainty when evaluating food allergy. OBJECTIVE: Our aim was to assess whether accounting for the ratio of component- or allergen-specific to total IgE can improve this prediction. METHODS: This multicenter study collected blood samples from children with suspected peanut or hazelnut allergy referred to allergy specialist clinics for food challenges. Specific IgE to peanuts, hazelnuts, and their components (Ara h 1, Ara h 2, Ara h 3, Ara h 8, Cor a 1, Cor a 8, Cor a 9, and Cor a 14) and total IgE levels were determined by using the ImmunoCAP-FEIA. Specific to total IgE ratios were compared with raw IgE levels in terms of discrimination and prediction. RESULTS: Eighty-eight (43%) of 207 children with suspected peanut allergy and 44 (31%) of 142 children with suspected hazelnut allergy had symptoms during food challenge. Discrimination was similar for raw and ratio measures: areas under the curve of 0.93 for Ara h 2-specific IgE versus 0.92 for the Ara h 2-specific/total IgE ratio and 0.89 for Cor a 14-specific IgE versus 0.87 for the Cor a 14-specific/total IgE ratio. The probability for a positive peanut challenge with 0.35 kU/L Ara h 2-specific IgE was 16% when the total IgE level was greater than 500 kU/L compared with 51%/48% for low/medium total IgE levels (<100/100-500 kU/L). A positive hazelnut challenge with 0.35 kU/L Cor a 14-specific IgE was estimated in 7% when total IgE levels were high compared with 34%/32% with low/medium total IgE levels. CONCLUSIONS: Raw Ara h 2- and Cor a 14-specific IgE levels were the best single predictors for pediatric peanut and hazelnut allergies, suggesting the omission of challenges at very high levels. Calculating ratio measures did not improve prediction in this population. However, estimation of individual probabilities for challenge outcomes could be supported by total IgE levels because high levels might indicate lower probabilities at a given component-specific IgE level.

FPIES: Data for Germany in international comparison.

Food protein-induced enterocolitis syndrome (FPIES) is a rare, non-IgE-mediated food allergy. The triggering foods differ significantly from the typical triggers of an IgE-mediated food allergy. Until recently, there were no data on triggers of FPIES in Germany. In order to create an advisory basis for the care of German patients, a large multicenter study was initiated and published at the end of 2021. This revealed clear differences in international comparisons. The most frequent triggers for FPIES in Germany are cow's milk, fish, vegetables, and meat. Most children (84%) react to only one food. The prognosis is usually good, depending on the trigger. Regional data should be used for counseling patients with FPIES. Specific recommendations for this are given in this article.

Different Patterns of Foods Triggering FPIES in Germany.

BACKGROUND: Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated gastrointestinal food allergy mainly affecting infants and young children. Allergic FPIES reactions differ from IgE-mediated food allergies, for example, regarding elicitors and clinical course. OBJECTIVE: The aim of our study was to describe causative agents and development of tolerance in German children with FPIES. METHODS: We conducted a retrospective survey on children with FPIES from 14 centers in Germany assessing a 6-year period. RESULTS: We analyzed 142 patients with 190 FPIES reactions, 130 of which met acute FPIES criteria and 60 were defined as chronic FPIES. The most frequent eliciting food for acute FPIES was cow's milk, followed by fish, vegetables (eg, potato, pumpkin), meats (eg, beef), and grains. A total of 119 children reacted to 1 food only, 16 children to 2 or 3 foods, and 7 children to ≥4 foods. In chronic FPIES, all but 4 exclusively breastfed infants reacted to cow's milk feeding. IgE sensitization to the triggering food was found in 21 of 152 (14%) cases. Two children developed additional IgE-mediated symptoms upon a food challenge. Time to proof of tolerance was shortest in cow's milk-induced FPIES, and it was shorter in chronic than in acute FPIES. CONCLUSION: In our national survey, we identified triggers for acute FPIES that partially differ from those reported internationally. Mainly foods introduced early in infant nutrition triggered acute reactions. Time to proven tolerance was shown to be contingent on FPIES symptomatology and on the triggering food. These data should be considered regarding nutritional advice for infants with FPIES.