BAFF/IL-10 and APRIL secreted from SLE-DCs contribute to IgG and IgA responses, respectively. (A) BAFF and APRIL secreted by monocytes, IFN-DCs, and SLE-DCs were measured by ELISA after 24-h culture in serum-free media. Combined data (mean ± SD) from experiments using sera from 10 SLE patients and monocytes from 8 healthy controls are presented. (B) Naive B cells were co-cultured with SLE-DCs or IFN-DCs for 12 d in the presence of 10 µg/ml control IgG, anti-BAFF, or TACI-Fc fusion protein. Ig production was detected by ELISA. Combined data (mean ± SD) from experiments using SLE-DCs generated with sera from 14 SLE patients and cells from 8 healthy controls are presented. For both SLE-DCs and IFN-DCs, monocytes from eight healthy controls were used. (C) IFN-DCs and SLE-DCs were co-cultured with naive B cells for 2 d. IL-10 levels in the supernatants were quantified by ELISA. Combined data (mean ± SD) from experiments using sera from eight SLE patients and cells from six healthy controls are presented. (D) IFN-DCs (top) and SLE-DCs (bottom) were cultured for 24 h and stained for intracellular IL-10 and IL-6. (E) After 24-h co-culture of naive B cells and IFN-DCs (top) or SLE-DCs (bottom), both DCs (gated on CD14⁺CD19⁻ cells) and B cells (gated on CD14⁻CD19⁺ cells) were stained for intracellular expression of IL-6 and IL-10. In D and E, experiments using four patient sera and cells from four healthy donors showed similar results. (F) IFN-DCs and SLE-DCs were co-cultured with naive B cells in the presence of 10 µg/ml control IgG or anti–IL-10/anti–IL-10R for 12 d. Ig production was measured by ELISA. Combined data (mean ± SD) from experiments using sera from 12 SLE patients and cells from 8 healthy controls are presented. In B and F, 50 nM CpG and 20 U/ml IL-2 were added to the cultures. Student’s t test: *, P < 0.05; **, P < 0.01.