Food‐specific IgA levels in esophageal biopsies are not sufficiently high to predict food triggers in eosinophilic esophagitis

BACKGROUND: Eosinophilic esophagitis (EoE) is an immune‐mediated disease, characterized by Th2‐type inflammation linked to specific foods. No currently available allergy tests reliably identify food triggers in EoE, leading to empiric dietary elimination strategies. Recently, milk‐ and wheat‐specific IgA in esophageal brushings were linked to clinical food triggers. In this study, we aimed to determine whether food‐specific IgA from esophageal biopsies is associated with known food triggers. METHODS: A prior cohort of 21 patients (median age 39 years) with confirmed EoE underwent empirical elimination diets and subsequent reintroduction of foods to determine triggers. Archived baseline biopsies were used to quantify levels of peanut‐, milk‐, soy‐, egg‐, wheat‐specific and total IgA by enzyme‐linked immunosorbent assay. RESULTS: Overall, 13 patients (62%) responded to the dietary elimination as determined by histology (<15 eos/hpf), with milk and egg being the most common triggers. Biopsies had varying amounts of total IgA, while food‐specific IgA was only detectable in 48 of 105 (46%) samples. Food‐specific IgA was normalized to total IgA for each sample and stratified by whether a food was a known trigger. For all foods tested, there were no significant differences in IgA between positive and negative triggers. CONCLUSIONS: Food‐specific IgA in esophageal biopsies was not associated with previously identified food triggers in this cohort. Future studies comparing food‐specific IgA in esophageal brushings, mucous scrapings, and biopsies from patients with known triggers will be critical to determining whether food‐specific IgA may serve as a biomarker for identification of EoE triggers.