CD19 and systemic sclerosis: As shown in Figure 4C, D, compared to HC, SSc patients showed a higher frequency of CD24highCD19+CD38high immature B cells (15.3% vs 9%, p<0.01; MFI 4119 vs 1344, p<0.05) and a lower occurrence of CD24+ CD19+CD38+CD27+ memory B lymphocytes (1.7% vs 3.5%, p <0.001) (Supplementary Figures S4C, D).