D1.284 - Eosinophilic Esophagitis Before and After Milk Oral Immunotherapy in Children with Food Allergy: A Case Series Including the Eosinophil-to-Lymphocyte Ratio

Oral immunotherapy (OIT) is increasingly used as a proactive treatment strategy in children with food allergy who are unlikely to develop natural tolerance. Eosinophilic esophagitis (EoE) is one of the most feared complications observed during OIT, with an estimated incidence ranging from 2.7% to 5.1. Endoscopic and histopathological evaluation is the gold standard for the diagnosis of EoE. The eosinophil-to-lymphocyte ratio (ELR), which can be assessed in peripheral blood, is being investigated as a supportive biomarker. This study aimed to evaluate the clinical characteristics and ELR levels of patients diagnosed with EoE before and after OIT.

Between 2022 and 2025, a total of eight children with IgE-mediated cow’s milk allergy who were scheduled for OIT and underwent endoscopic evaluation before and after OIT at the Akdeniz University Pediatric Allergy and Immunology Department were included. Demographic characteristics, clinical findings, comorbid atopic diseases, milk- and casein-specific IgE levels, and peripheral blood eosinophil and lymphocyte counts were recorded. ELR was calculated by dividing the absolute eosinophil count by the absolute lymphocyte count. The diagnosis of EoE was established based on the presence of ≥15 eosinophils per high-power field in esophageal biopsy specimens.

A total of eight children with cow’s milk allergy scheduled for oral immunotherapy were included. The mean age was 5.6 ± 2.5 years, and 50% were male. Eosinophilic esophagitis was detected in two different patients, one before OIT and the other during follow-up after OIT. The median ELR was 0.47 (IQR: 0.43–0.52) in patients with EoE, whereas it was 0.23 (IQR: 0.18–0.27) in patients without EoE (p=0.03). In addition, the mean casein-specific IgE level was significantly higher in patients with EoE (72.6 ± 18.4 kUA/L) compared with those without EoE (14.2 ± 9.6 kUA/L, p=0.02).

This case series demonstrates that eosinophilic esophagitis can be detected both before and after oral immunotherapy in children with food allergy. The elevated ELR levels observed in patients with EoE suggest that this parameter may serve as a supportive biomarker for the presence of EoE. Larger prospective studies are needed to clarify the clinical utility of ELR and casein-specific IgE in the monitoring of patients undergoing OIT.