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Th17 cells are different from Th1 and Th2 cells. They are differentiated from memory CD4+ T cells and naive T cells induced by interleukin ��IL-6, transforming growth factor ��TGF�� β, IL-1 β or IL-23. Mature Th17 cells can secrete many cytokines, such as IL-17, IL-22, etc, and play a crucial role in the pathological process of autoimmune diseases, host defense, inflammatory diseases, tumors and graft-versus-host diseases. This review presents the differentiation and related cytokines of Th17 cells as well as their roles in the pathogenesis of skin diseases.

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