Translational mini-review series on Th17 cells: are T helper 17 cells really pathogenic in autoimmunity?

In this review the authors discuss the evidence for T helper type 17 (Th17) cells as pathogenic T cells in autoimmunity. Studies with cytokine-deficient mice or blocking of interleukin (IL)-17, IL-21 and IL-22 have resulted in a conflicting data set. Although in the experimental autoimmune encephalomyelitis model the role of Th17 cells remains a point of debate, this IL-17-producing T cell in experimental arthritis is clearly contributing to inflammation and destruction.