CD27 and rheumatoid arthritis: Sex significantly influenced the composition of CD27+IgD- postswitch memory, CD27-IgD+ naïve and CD27-IgD- B cells in controls (with, respectively, 10.9 (5.9 to 13.5), 76.7 (73.1 to 83.4) and 2.2 (1.7 to 2.5) in men and 20.9 (12.4 to 27.9), 65.7 (49.9 to 76.4) and 4.4 (2.8 to 7.4) in women; all P < 0.05), but not in RA patients.