The results showed that the proportion of CD19+CD27+ B cells (memory B cells) was reduced in active SLE patients (32.2±2.0% versus 19.6±2.3%), but their mortalities had no difference (3.0±0.3% versus 3.2±0.5%) compared with healthy donors (Figure 1f). Here, CD19 is linked to systemic lupus erythematosus.