PTGS2 and eosinophilic esophagitis: Cells from a pathogenic effector T helper 2 (peTH2) subset were enriched for expression of arachidonic acid metabolism and eicosanoid production genes (e.g., PLA2G16, PTGS2, HPGDS, and ALOX5AP), expressed the T cell gastrointestinal and skin homing factor GPR1519,20, and displayed evidence of clonal expansion in three of the four patients with active EoE in whom multiple TCR sequences were recovered.