Patients with active RA (DAS28 ≥ 3.2 and n = 20) had greater proportions of helper T cells (THs; CD3+CD4+CD8−), IL-17-producing helper T cells (TH17s; CD3+CD4+IL-17+), and Tregs (CD3+CD4+CD25+FOXP3+) and smaller proportions of cytotoxic T cells (TCs; CD3+CD8+CD4−) than patients with inactive RA (DAS28 < 3.2 and n = 20; Figure 1A,B). Here, IL17A is linked to rheumatoid arthritis.