It is considered that pro-inflammatory cytokines, such as TNFα, IL-6 and IL-23, produced by innate immune cells promote and sustain chronic mucosal inflammation in co-ordination with effector cytokines, such as IL-17 and IL-22, produced by lymphocytes in both mouse and human IBD31. This evidence concerns the gene IL17A and inflammatory bowel disease (infantile ulcerative colitis) 31, autosomal recessive.