CD38 and rheumatoid arthritis: The two CD11c+ B-cell populations were significantly higher in the SLE group than in the other three groups: MC09 (CD11c+/CD38−/CD185−) (HCs: 0.562%; RA: 0.785%; SSc: 0.571%; SLE: 2.312%) and MC16 (CD11c+/CD183+) (HCs: 0.337%; RA: 0.356%; SSc: 0.364%; SLE: 0.838%).