Peripheral blood from patients with active EoE have increased frequency of circulating activated eosinophils and IL-5-expressing CD4+ T cells, and peripheral blood mononuclear cells from EoE patients produce significantly more IL-5 compared to healthy controls when stimulated with house dust mites, ragweed, milk, Aspergillus fumigatus, or soy (55–59). This evidence concerns the gene CD4 and eosinophilic esophagitis.