The molecular features at the IL19 locus may modestly alter the establishment of HIV-1 infection. Interleukin (IL) 19, IL-20, and IL-24 belong to the IL-10 cytokine family and have been identified to play a role in the regulation of epidermal functions and inflammation. The expression of IL19 in biopsies of patients with active ulcerative colitis was increased compared with patients with quiescent ulcerative colitis and that colitis was attenuated in IL-19-deficient mice. The disruption of the epithelial barrier with dextran sodium sulfate leads to increased IL-19 expression. Attenuated colitis in IL-19-deficient animals was associated with reduced numbers of IL-6-producing macrophages in the inflamed colonic lamina propria. Microbial-driven expression of IL-19 by intestinal macrophages may contribute to the pathogenesis of inflammatory bowel disease.