Mucosal penetration and clearance of gluten and milk antigens in eosinophilic oesophagitis

Summary Background The Th2 allergic pathway in eosinophilic oesophagitis (EoE) responds to food antigen exposure. Aim To compare the presence and temporal pattern of food antigen penetration in oesophageal mucosa in active and inactive EoE and controls Methods Thirty‐two patients with EoE (20 active) and 10 controls were asked to eliminate all wheat and/or dairy 12, 24, 48, 72 or 96 hours before endoscopy. Immunostaining on endoscopic biopsies was performed for gliadin, casein and whey. Results Gluten, casein and whey were detected by positive staining in 17/32 (53.1%), 21/32 (65.6%), and 30/32 (92.0%) of patients, respectively. In active vs inactive EoE, 70.0% vs 25.0% ( P < 0.05), 80.0% vs 41.5%, and 90.0% vs 90.9% patients had detectable gliadin, casein and whey, respectively. Casein and whey (20.0% and 100%, respectively) but not gliadin, were present in controls. The gliadin staining density was greater in active compared to inactive disease at ≤ 24 vs >24 hours after exposure ( P = 0.05) but no differences were detected when comparing active and inactive patients for casein and whey. There was greater staining density for whey than casein for all patients at ≤24 hours (mean 2.14 ± 0.91 and 1.07 ± 1.33, P = 0.02). In active EoE, IgG4 was present in 14/20 compared to one inactive patient. Conclusion The oesophageal epithelium is selectively permeable and has relatively long dwell times for food antigens known to trigger EoE. The precise mechanism of antigen‐specific mucosal entry and the factors that determine the induction or effector trigger of the Th2 pathway activation merit further study.