IL6 and immunoglobulin G4-related sclerosing disease: Serum levels of IL-4 in patients with IgG4-RD (6.54 ± 5.67 pg/mL) were significantly higher than those in HC (1.69 ± 1.46 pg/mL; P <0.001), and there were no significant differences between IgG4-RD and pSS patients (6.52 ± 6.14 pg/mL) (Figure 5A), Serum levels of IL-6 in patients with IgG4-RD (2.14 ± 1.66 pg/mL) were significantly higher than those in HC and pSS patients (0.68 ± 0.39 pg/mL, P <0.001; 1.35 ± 1.40 pg/mL; P = 0.002; Figure 5B).