IL17A and immunoglobulin G4-related sclerosing disease: Serum levels of IL-17A in patients with IgG4-RD (0.40 ± 0.57 pg/mL) were comparable to those in HC (0.24 ± 0.15 pg/mL; P = 0.482), and both were significantly lower than in patients with pSS (1.10 ± 1.37 pg/mL; Figure 5H).