Oral immunotherapy for hazelnut allergy: a single-center retrospective study on 100 patients

Background: Oral immunotherapy (OIT) protects patients with IgE-mediated food allergies from food-induced allergic reactions due to accidental exposure and may improve their quality of life. This approach has never been evaluated for hazelnut, a major cause of food allergy in Europe. Objective: We sought to determine the rate of hazelnut-desensitized patients after 6 months of OIT and to identify predictors of successful desensitization. Method: In a retrospective single-center study, we included patients under 18 years old who had followed at least 6 months of hazelnut OIT for IgE-mediated allergy defined as the combination of a history of hypersensitivity reaction after hazelnut ingestion, a positive hazelnut Skin Prick Test (SPT) or serum IgE and a positive double-blind placebo-controlled food challenge (DBPCFC). We assessed the rate of desensitized subjects, patients able to tolerate 1635 mg of hazelnut protein (approximately 8 hazelnuts with each hazelnut approximately equivalent to 200mg of protein), after 6 months of hazelnut OIT, associations between baseline variables and successful desensitization, and OIT-related adverse reactions. Results: One hundred patients were included (64% males, median age: 5 years). Hazelnut hypersensitivity occurred as a severe reaction in 7% of cases. At 6 months, the rate of desensitized subjects was 34%, 95%CI: 25-44. The eliciting dose that is the amount of hazelnut protein provoking a hypersensitivity reaction during the DBPCFC increased from 106 [51-249] mg at baseline to 523 [190-1635] mg at 6 months of OIT (p<0.0001). In a multivariate analysis, successful desensitization was associated with age (OR: 1.5, 95%CI: 1.2;2.2), hazelnut SPT wheal diameter (OR: 0.61, 95%CI: 0.4;0.8) and specific IgE level (OR: 0.86, 95%CI: 0.72;0.098), and cashew allergy (OR: 0.42, 95%CI: 0.12; 0.64). Adverse reactions occurred in 32% of patients. None were severe. Conclusion: In a cohort of 100 patients aged 3-9 years, our results show for the first time that hazelnut OIT is associated with hazelnut desensitization and may be safe in the majority of patients undergoing this therapy.