T helper (Th) cells that secrete interleukin-17 (IL-17), called Th17 cells, are a subpopulation of CD4+ T cells that are involved in the disease progression of many autoimmune and inflammatory disorders due to their secretion of the IL-17 family cytokines IL-17A and IL-17F as well as IL-22 and granulocyte-macrophage colony-stimulating factor (GM-CSF). Here, IL17A is linked to Autoimmunity.