Children (aged 1 to 18 years) presenting with symptoms suggestive of EoE and requiring an upper gastrointestinal endoscopy with biopsies of the esophageal mucosa in order to confirm or exclude the diagnosis of EoE will be included.~Children paired for age in whom an endoscopy performed to explore symptoms of EoE revealed another condition (peptic oesophagitis, achalasia), or children paired for age in whom an endoscopy with biopsies has been performed to explore chronic abdominal or epigastric pain or suspected chronic inflammatory bowel disease, will be include as control subjects.~The endoscopy will be performed under general anaesthesia using a flexible endoscope with an external diameter of between 4.9 and 9.2 mm, depending on the size of the child. In line with the guidelines, eight biopsies will be collected from the proximal, median and distal oesophagus for the routine analysis of esophageal remodelling and inflammation. Three of these biopsies will be used in the context of this study to analyse innate immune cells using flow cytometry and to determine the profile of cytokine expression. Two biopsies will be placed in sterile, 0.5 ml Nunc tubes containing a storage buffer (MACS® Tissue Storage Solution) and then stored in ice until the extraction of cells for cytometric analysis. The third specimen will be placed in a sterile tube and frozen immediately in liquid nitrogen for analyses of the esophageal microbiome.~ILC1, 2 and 3 and their sub-types will be identified by means of structural criteria (size and granularity) and differential membrane and intracellular labelling using the specific markers shown below. All acquisitions and analyses will be achieved using a 13-colour NovoCyte cytometer (AACEA) and its associated software (NovoAxpressTM), which are available in the laboratory.
The main aim of this study is to assess the expression of innate lymphoid cells in the esophageal mucosa of children with eosinophilic esophagitis (EoE) and in control subjects