Comparative evaluation of CD5 B cells in patients with rheumatoid arthritis and essential mixed cryoimmunoglobulinemia using FACS analyzer and FACSCAN flow cytometer.

In this study, using both a FACSCAN flow cytometer and the FACS analyzer, and two-color fluorescence, CD5 B cells have been enumerated in the peripheral blood (PB) of normal controls (NC) and patients with rheumatoid arthritis (RA) or essential mixed cryoimmunoglobulinemia (EMC). Using a FACSCAN flow cytometer, no significant difference was observed between the percentage of CD5 B cells in the NC (21.24% +/- 3.71) and RA (24.83% +/- 3.85), or EMC (21.03% +/- 6.38). Using the FACS analyzer, however, there was significant difference between the NC (9.14% +/- 3.82) and EMC (2.84% +/- 2.58) (p less than 0.05), but no significant difference between the NC and RA (7.17% +/- 2.55). Further analysis of 10,000 B cells selected by live gating showed that there were three populations of B cells, with the majority of B cells unstained, a small number of cells brightly stained for CD5 in the NC (3.78% +/- 1.09) or RA (2.80% +/- 0.96), and about 6.45% to 9.43% with intermediate staining in patients with RA and the NC, respectively. In addition, serum low molecular weight IgM (LMW IgM) from patients with RA was detected by an enhanced chemiluminescence detection system combined with a modified immunoblot technique. A significant linear correlation was observed between the percentage of CD5 B cells and the height of LMW IgM peak (r = 0.69, p less than 0.05).