CD38 and rheumatoid arthritis: However, the percentage of CD38+ DN B cells was higher in patients with SLE than in the control (median: 1.3% vs. 0.3%, p < 0.001), RA (median: 1.3% vs. 0.4%, p = 0.001), and SPA groups (median: 1.3% vs. 0.5%, p = 0.047).