IFNG and Crohn disease: Fractalkine expression is upregulated by inflammatory cytokines (IFN-γ, IL-1β and TNF-α) or by direct leukocyte contact (Muehlhoefer et al., 2000; Sans et al., 2007), and has been detected in intestinal epithelial cells and endothelial cells both in normal small intestine and in active Crohn’s disease mucosa (Muehlhoefer et al., 2000).