Is the etiology of eosinophilic esophagitis in adults a response to allergy or reflux injury? Study of cellular proliferation markers

SUMMARY Recent research suggests that allergy may be the key factor in the etiology of eosinophilic esophagitis (EE); however, historically, the condition was hypothesized as related to reflux injury to the esophageal mucosa. We studied this hypothesis by comparing markers of inflammation and cellular proliferation in EE and reflux esophagitis. Lower esophageal biopsies of adult patients with EE (n = 10), reflux esophagitis (n = 8), and normal controls (n = 13) were assessed quantitatively for the expression of the cyclooxygenase‐2 (COX‐2) enzyme, cellular proliferation, and oncogenic resistance to apoptosis using monoclonal antibodies for COX‐2, Ki‐67, and Bcl‐2, respectively. Normal esophageal epithelium demonstrated weak diffuse uptake of COX‐2 stain in the basal layer. No COX‐2 expression was demonstrated in the EE group, significantly less than the control and reflux groups (P