Since different innate immune cells, like DC and macrophages, and their inflammatory cytokines, such as IL-1β, IL-6, IL-21, and IL-23, have a key role in promoting the differentiation and proliferation of Th17 cells, the use of neutralizing monoclonal antibodies for these cytokines or the antagonism of their receptors may well be a reasonable strategy for the treatment of IBD. This evidence concerns the gene IL21 and inflammatory bowel disease.