Is Immunofluoresence Staining for Eosinophil Derived Neurotoxin Useful in the Diagnosis of Eosinophilic Esophagitis?

Abstract

Purpose: We have shown that patients with low level esophageal eosinophilia (1–20 eos/hpf) have similar demographics, dysphagia history, and endoscopic findings as patients with classic eosinophilic esophagitis (EoE) with 20 eos/hpf. Some of the low-level eosinophilia patients will have eosinophil counts >20 /hpf at a second endoscopy and will have resolution of their dysphagia with topical steroid therapy. Other low-level eosinophilia patients will have resolution of dysphagia with PPI therapy. Esophageal eosinophil counts can fluctuate with time, and maximum eosinophil counts in esophageal mucosa might not be the best diagnostic tool for the diagnosis of EoE. We performed immunofluorescence staining of esophageal biopsy specimens for Eosinophil Derived Neurotoxin (EDN) in several groups of patients to evaluate its potential use as a marker for EoE. Methods: We performed staining for EDN with qualitative and semiquantitative analysis of esophageal biopsy specimens from four groups of patients: A) normals, B) low level eosinophilia –GERD patients (LL-GERD) (LA grade B-D esophagitis and dysphagia responding to PPI therapy), C) low level eosinophilia – emerging EoE patients (LL-EE) (>20 eos/hpf on second endoscopy and dysphagia response to topical steroid therapy), and D) classical EoE patients (25 to 100 eos/hpf). Specimens were scored on a 0–3 scale for intracellular (IC) and extracellular (EC) EDN deposition by two authors, and the scores were averaged. Results: The semiquantitative results are displayed in Table 1. IC and EC EDN scores were negligible in the normals and elevated in the other groups. The EC EDN score and percentage of patients with an abnormal score (>1.3) trended to be higher in the EoE and LL- EoE groups. Qualitatively, intense extracellular EDN deposition was typically observed in the papillae and on the luminal surface of the epithelium in biopsies from the EoE patients, while deposition in the LL-GERD patients, with one exception, was scattered throughout the mucosa with relatively little uptake on the luminal surface and in the papillae. The LL-EoE group had a very similar pattern to the EoE group.Table 1Conclusion: This pilot study suggests: 1) Patients with low level eosinophil density in esophageal biopsies have significant EDN immunofluorescence staining. 2) EDN staining particularly extracellular staining on the luminal mucosa has potential to be a better marker for EoE than maximum eosinophil count and should be further evaluated.