Recombinant IFN-α enhances cytokine production in B cells costimulated with B-cell antigen and CpG. B cells (2 × 105 B cells/200 μL/well) were incubated in the presence or absence of CpG-B (3 μg/mL), anti-Ig (10 μg/mL), and increasing concentrations of recombinant IFN-α (500, 1500, and 6000 IU/mL). After 72 hours, IL-6 (A), TNF-α (B), and IL-10 (C) concentrations were determined in the supernatants by ELISA (medium, closed symbols; CpG, open squares; anti-Ig, open triangles; and CpG + anti-Ig, open circles. The means ± SEM of 4 independent experiments are shown (*P < .05, evaluation for B cells stimulated with recombinant IFN-α as compared to B cells stimulated with anti-Ig and CpG alone). (D) B cells were incubated alone (□) or in the presence of PDCs (▪) and were stimulated with CpG-C, anti-Ig, or a combination of CpG-C and anti-Ig. The biologic activity of type I IFN (IFN-α and IFN-β) was blocked by a combination of anti–IFN-α, anti–IFN-β, and anti–IFN-α/-β receptor antibodies (▨). After 72 hours, IL-6 was measured by ELISA (means of 2 independent experiments).
