CD19 and immunoglobulin G4-related sclerosing disease: The percentages of CD19+ B cells were significantly increased in IgG4-RD patients (6.43 ± 2.73%) compared to HC (4.41 ± 1.75%; P = 0.001), but were lower than in pSS patients (8.97 ± 4.40%; P <0.001; Figure 1B).