[Research advances in Th17 cells].

CD4+ T cells have been divided into different subsets, essentially based on the cytokines they produce. These subsets include T helper cell (Th)1, Th2 and regulatory T cells (Treg). Recently, another subpopulation of T cells has been identified, and it was named as Th17, which is characterized by the release of interleukin (IL)-17. The discovery of Th17 cells is not only a challenge to some traditional theories, such as the differentiation of CD4+ T cells and the drift theory of Th1/Th2, but also provides new research approach to inflammatory and immunologic diseases, especially, the balance among Th1, Th2, Treg and Th17 cells may play an important role in maintaining the normal immune response.