CD80 and peeling skin syndrome: The results revealed that CD19+ B lymphocytes in IgG4-RD patients expressed significantly higher CD80 and CD86 (43.27 ± 8.64%, 47.18 ± 14.23%, respectively) than in pSS patients (23.69 ± 14.24%; P = 0.037 and 27.45 ± 12.17%; P = 0.041; respectively) and HC (17.54 ± 7.41%; P <0.001 and 19.56 ± 7.70%; P = 0.002, respectively; Figure 2K-M).