CD19 and systemic lupus erythematosus: Interestingly, both the proportion of CD19+ B cells in SLE lymphocytes (8.1±0.6% versus 15.0±2.6%) and the percentage of dead CD19+ B cells in total CD19+ B cells were increased (12.0±0.7% versus 17.8±2.6% ) compared with healthy donors (Figure 1e).