The proportions of BAFF-R + mature B cells were significantly decreased in IgG4-RD patients compared with pSS patients and HC (72.27 ± 28.91%, 92.59 ± 92.7%, and 97.78 ± 1.51%, respectively; P <0.05; Figure 2D). Here, TNFRSF13C is linked to immunoglobulin G4-related sclerosing disease.