Su1118 Eosinophilic Esophagitis Is Characterized by Tissue Infiltration of a Distinct Subset of Eosinophils Expressing High Levels of Integrin aM/Cd11b

Objectives: Children with eosinophilic esophagitis (EoE) require frequent evaluation of mucosal inflammation. Esophageal endoscopy and histopathological examination of biopsies remain the gold standard method of assessing the disease. We hypothesized that measuring eosinophil-derived proteins in samples obtained by esophageal brushing would be accurate in diagnosing and monitoring the disease. Methods: Esophageal mucosal samples were collected by brushing middle and distal esophagus with two separate cytology brushes (Kimberley Clarke # 60314) during routine esophagogastroduodenoscopy (EGD). Specimens from the brushes were extracted and eosinophilic degranulation proteins [Eosinophil-derived neurotoxin (EDN) and Eosinophil cationic protein (ECP)] were measured by ELISA in serially diluted samples. To evaluate the utility of EDN and ECP biomarkers in diagnosing active EoE along with the eosinophil (Eos) counts, receiver operating characteristics (ROC) curves were constructed to calculate area under the curve (AUC). Results: Esophageal brushings were performed in 37 children (19 male; mean age: 11 years) with active EoE [n=17; mean Eos count = 30/high power field (hpf)], EoE in remission (n=6; mean Eos count = 4/hpf), gastro-esophageal reflux disease (GERD; n=6; mean Eos count = <1) and controls with normal esophagus (n=8; mean Eos count = 0). Levels of EDN and ECP correlate with activity of the disease and were significantly higher in patient with active EoE compared with treated EoE, GERD and controls (P<0.01). Quantities of EDN and ECP proteins have exhibited high sensitivity and specificity for diagnosing active EoE (94% and 95% respectively for EDN and 94% and 90% respectively for ECP). The AUC for diagnosis of active EoE was 0.95 for EDN and 0.90 for ECP. Conclusion: Eosinophil-derived proteins measured in esophageal brushing samples accurately diagnose active EoE in children. Esophageal brushing might potentially provide more precise and reliable samples than those obtained by an esophageal string test and it reduces the chance of sampling error due to irregular distribution of inflammation. Further studies are needed to compare blind esophageal brushing with brushing during endoscopy.