CD19 and rheumatoid arthritis: We found significant differences among the populations of CD19+ICOSL+ B cells in PB samples of patients with Hi-RA (13.57 ± 2.44%, P = 0.0033), Mo-RA (10.53 ± 1.68%, P = 0.0255) and Re-RA (4.87 ± 0.89%; Figure 2E).