Regulatory effect of peripheral blood B cells. Monocytes were purified from the peripheral blood of (A) healthy donors, (B) patients with SLE, or (C) patients with RA and stimulated with GM-CSF (1000 U/mL) and IL-4 (500 U/mL) for 6 days. The differentiated immature DCs were stimulated with LPS (100 ng/mL) and IFN-γ (1000 U/mL) for 24 hours to generate mature DCs. Peripheral blood B cells were stimulated for 5 days on CD40L-transfected NIH-3T3 murine fibroblasts in the presence of 0.25μM CpG-ODN 2006. (A) B cells from healthy donors were added to their autologous DCs (ratio 1 DC/4 B cells) either nonstimulated (NS) or stimulated (S) with their supernatant. MFI of HLA-DR (7 samples), percentages of CD80^low (8 samples), CD86^low (8 samples), and IL-12^low (7 samples) DCs were evaluated by flow cytometry on CD19-negative cells. (B) B cells from patients with SLE or (C) from patients with RA were activated as described previously and added with their supernatant to autologous DCs. MFI of HLA-DR (6 and 8 samples for SLE and RA patients, respectively), percentages of CD80^low (8 and 10 samples for SLE and RA patients, respectively), CD86^low (6 and 10 samples for SLE and RA patients, respectively), and IL-12^low (7 and 10 samples for SLE and RA patients, respectively) DCs were evaluated by flow cytometry on CD19-negative cells. Activated tonsillar B cells were used as controls (Ctrl). *P < .05; **P < .01; ns, nonsignificant.