Interleukin-17A (IL17A), a characteristic cytokine produced by the T helper 17 cells (Th17 cells), can form either a homodimer or a heterodimer with IL17F.It is produced not only by Th17 cells, but also by cytotoxic CD8+ T cells (Tc17 cells), ?d T cells, invariant natural killer T cells (iNKT cells), lymphoid tissue inducer cells (LTi cells), and other hematopoietic and non-hematopoietic cells. During development, these cells exhibit flexible or plastic features distinct from those of Th1 and Th2 cells. IL17A plays important roles in the pathogenesis of autoimmune diseases and in the host defenses against bacterial and fungal infections.Expression of IL17A and its related factors, as well as the infiltration of IL17A-producing cells into the tumor microenvironment, has been implicated in anti-tumor or pro-tumor effects in various cancers
