(a) Histogram depicting the distribution of B-cell frequencies in the peripheral circulation from 94 rheumatoid arthritis (RA) patients. The percentage of CD19+ cells from total peripheral lymphocytes is plotted on the x axis, and the number of patients in each frequency range is plotted on the y axis. The overlays represent the Gaussian frequency distributions fitted to the two populations. (b) Percentage of CD19+ B cells in the peripheral circulation in patients negative (SE-) and positive (SE+) for the RA-associated shared epitope and in age-matched healthy controls. Bars depicts mean and standard error of the mean. *P = 0.05 compared with healthy controls, **P = 0.02 compared with healthy controls, ***P < 0.001 compared with SE-positive RA patients.