CD19 and systemic lupus erythematosus: Conversely, the frequencies of IgM memory B cells (CD19+CD27+IgD+), class-switched memory B cells (CD19+CD27+IgD-), and naïve B cells (CD19+CD27-IgD+) differed significantly among the active, inactive SLE patients and HC groups (Figure 3B), and interestingly, the frequencies of plasmablast were positively associated with SLEDAI score (r=0.7664, p<0.0001), anti-ANA titers (r=0.5210, p=0.0032) (Figure 3C).