IGHG4 and synovial sarcoma: Among the top up-regulated genes found in the salivary gland of pSS patients in this study, most have been identified in the parotid gland saliva or peripheral blood of primary SS patients in previously published studies, such as MS4A1(CD20) (24), IGHG4 (25), CXCL13 (26, 27), TAP1 (28, 29), CD52 (30), PSMB8-AS1 (29), FPR3 (30), PSMB9 (31), and GBP1 (32, 33).