Patients with SLE had an increased frequency of Th17 cells compared with healthy controls (mean ± SD, 1.8 ± 1.26% versus 0.6 ± 0.27%; P < 0.001) (Figure 1b), as well as an increased frequency of IL-17 and IFN-γ double-positive cells (0.46 ± 0.41% versus 0.21 ± 0.14%; P = 0.005) (Figure 1c), although patients and controls had similar frequencies of Th1 cells(17.1 ± 9.23% versus 15.5 ± 5.47%; P = 0.457) (Figure 1d). Here, IL17A is linked to systemic lupus erythematosus.