Phenotypic and functional features of human Th17 cells

T helper (Th) 17 cells represent a novel subset of CD4+ T cells that are protective against extracellular microbes, but are responsible for autoimmune disorders in mice. However, their properties in humans are only partially known. We demonstrate the presence of Th17 cells, some of which produce both interleukin (IL)-17 and interferon (IFN)-gamma (Th17/Th1), in the gut of patients with Crohn's disease. Both Th17 and Th17/Th1 clones showed selective expression of IL-23R, CCR6, and the transcription factor ROR gamma t, and they exhibited similar functional features, such as the ability to help B cells, low cytotoxicity, and poor susceptibility to regulation by autologous regulatory T cells. Interestingly, these…