Detection of Eosinophilic Cell-free Granules Based on Expression of CCR3 and MBP Markers in Esophageal Biopsy Specimens of Patients with Suspected and Confirmed Eosinophilic Esophagitis

Purpose: Eosinophilic esophagitis (EoE) is the most well-known eosinophilic gastrointestinal disorder (EGID) characterized by the presence of a high number eosinophils within the esophageal epithelium and the clinical signs. Biopsies of patients with suspected EoE may not show a high number of eosinophils, however the presence of granules may help with the diagnosis. This study aims to evaluate the presence of cell-free eosinophil granules in the esophageal tissue of patients with suspected and confirmed EoE to accelerate the diagnosis and treatment of patients with low eosinophil count. Methods: Fifteen patients with confirmed EoE and 15 suspected of EoE were included in this study. Patients' esophageal tissue biopsies were stained using immunohistochemistry (IHC) to identify eosinophils and their cell-free granules. For testing, anti-major basic protein (MBP) and anti-chemokine receptor type 3 (CCR3) were used as primary antibodies and a double-staining kit containing secondary antibodies conjugated to the enzyme and related chromogens were used. Results: Cell-free granules with different degrees were observed in 53.3% and 93.3% of suspected and confirmed EoE samples, respectively. Furthermore, in esophageal biopsy of 73.3% of patients with suspected and 93.3% of patients with a definitive diagnosis of EoE, basal layer hyperplasia (BLH) was recognized. Conclusion: The results of the present study showed that IHC can be applied to detect cell-free eosinophil granules in esophageal tissue. Observation of granules and basal cell hyperplasia in biopsies of suspected EoE patients whose eosinophil count is below the threshold can be valuable findings to make a definitive diagnosis for these patients.