FOXP3 and immunoglobulin G4-related sclerosing disease: CD4+Foxp3+ Treg were significantly increased in patients with IgG4-RD compared to HC and pSS patients (71.11 ± 7.3 cells/μl versus 57 ± 6.8 and 46.8 ± 8.3 cells/μl; p = 0.01 and p = 0.02, respectively) (Figures 2A,B).