The research indicates that if this balance is tilted towards Th1 and Th17 cells in the serum and joint fluid of RA, it can lead to increased levels of inflammatory cytokines such as lL-2 and interferon (IFN)-γ secreted by Th1 cells and cytokines such as IL-17 secreted by Th17 cells. Here, IL17A is linked to rheumatoid arthritis.