For example, abnormally activated intestinal macrophages in IBD patients and experimental models of colitis produce various inflammatory cytokines, such as IFNγ, IL‐1β, IL‐6, IL‐17, IL‐23 and TNF‐α necessary for T‐cell differentiation, specifically inducing the production of Th1 and Th17 cells (191‐194). The gene discussed is IL17A; the disease is colitis.