Type 17 T helper (TH17) cells are a population of CD4+ effector T cells that are distinct from TH1 and TH2 cells owing to their ability to produce interleukin (IL)-17. Although TH1 and TH2 cells are similar in mice and humans, TH17 cells differ in several ways. The differentiation of mouse TH17 cells requires transforming growth factor beta and IL-6, whereas human naive T cells can develop into TH17 cells in the presence of IL-1beta and IL-23 alone, transforming growth factor beta having an indirect role in their development via the selective inhibition of TH1 cell expansion. in both mice and humans, a late developmental plasticity of TH17 cells towards the TH1 lineage has been shown. Mainly based on mouse gene knockout studies, TH17 lymphocytes have been found to have a pathogenic role in several autoimmune disorders; however, whether human autoimmune disorders, including rheumatoid arthritis (RA) and psoriasis, are prevalently TH1-mediated or TH17-mediated, is still unclear. research suggests that both TH1 and TH17 cells are involved in RA pathogenesis, raising the possibility that interventions that target both the IL-23-IL-17 (TH17) and the IL-12-interferon gamma (TH1) axes might be successful future therapeutic approaches for RA.