Eosinophilic esophagitis (EoE) is a food allergen disorder driven by antigen recognition in the gastrointestinal tract. The study by Warners et al. , strongly supports the esophageal epithelium as the area of disturbed permeability and primary target for initiation of the TH2-induced allergic pathway. In contrast, small bowel assessment reveals a lack of clear change in aspects of permeability compared to controls. It is not clear, however, if the available testing used for this purpose accurately assesses the mechanisms by which antigen recognition may occur in this organ. As a result, the role of the small bowel in EoE remains unclear. Am J Gastroenterol 2017; 112:1072-1073 doi: 10.1038/ajg.2017 Th at immune recognition of food antigens in the gastrointestinal tract is a key and primary event in eosinophilic esophagitis (EoE) is indisputable. Th e fi rmest support for this principle is evidenced by the response of EoE to an elemental diet, that is, a diet of nutrients devoid of food allergens. In children, this response is nearly 100% ( 1 ) whereas in adults, it is about 80% ( 2,3 ). Th e presence of confounding gastroesophageal refl ux disease could account for the lower response in adults. Nevertheless, some controversy exists as to where this antigen recognition occurs. To date, studies have primarily emphasized the role of the esophagus. Many types of data support this emphasis. For example, the esophageal epithelium in active EoE is characterized histologically by dilation of intercellular spaces, which theoretically would facilitate transport of fl uids, ions, and proteins. Th e epithelium has also been demonstrated to lose its integrity as evidenced by increased fl ux in Ussing Chamber studies ( 4 ) and increased fl ow of current on impedance measurement ( 5 ). Indeed, investigators have demonstrated a decrease in both tight junction proteins ( 6 ) and desmosomes ( 7 ), two of the key regulators of intercellular space function, in active disease with restoration of normal levels in treated disease. Finally, the complex immune pathway involving a TH2 reaction in the esophagus with activation of multiple cytokines, and recruitment and degranulation of copious eosinophils has been carefully characterized in both animals ( 8 ) and humans with EoE. As a result, the evidence that the esophageal epithelium is the sole culprit in EoE would seem insurmountable.On the other hand, intuition suggests that this seems unlikely. Aft er all, a bolus of food has only 10 s to be exposed to esophageal mucosa. How could such transient mucosal contact lead to an unrelenting chronic infl ammatory disease that commonly leads to diff use stricture formation. Ingested food also is non-digested. In other words, there is minimal exposure of the antigen as it is enveloped in the complex food bolus. Furthermore, the esophagus is hardly known as an immunogenic organ. It is normally devoid of eosinophils, has few lymphocytes and has not been described as an organ capable of allergic disease until now. As a result, this begs...