CD38 and rheumatoid arthritis: ERA and established RA patients had similar circulating levels of transitional (IgD+CD38++), naïve (IgD+CD27-), pre-switch memory B cells (IgD+CD27+), post-switch memory B cells (IgD-CD27+) and plasmablasts (IgD-CD38+++) in comparison with controls and no significant differences were observed between the two patient groups (Figs 2 and 3).