The esophageal mucosa of active EoE patients contains activated Th2 cells that secrete increased levels of the inflammatory cytokine LIGHT, a member of the tumor necrosis factor (TNF) superfamily that promotes the presence of resident esophageal mucosal fibroblasts and their migration to the epithelium, where they directly interact with eosinophils. The gene discussed is TNF; the disease is eosinophilic esophagitis.