CD19 and rheumatoid arthritis: In detail, the mean frequency of CD19+CD95+ expressing cells was as follows: in post-switch memory (CD19+IgD-CD27+CD95+) cells (p < 0.0001, mean ± SEM in RA = 38.9 ± 1.5% vs. HD = 18.6 ± 1.4%); in pre-switch memory (CD19+IgD+CD27+CD95+) B cells (p < 0.0001, RA = 19.7 ± 1.2% vs. HD = 9.2 ± 0.96%); in DN B cells (p < 0.0001, RA = 22.1 ± 1.0% vs. HD = 12.0 ± 0.9%); and in naïve B (CD19+IgD+CD27-CD95+) cells (p = 0.018, mean ± SEM in RA = 1.3 ± 0.1% vs. HD = 0.86 ± 0.1%).