GM-CSF-matured pDCs modulate the Th1/Th2 balance during T helper cell differentiation. (A) Surface phenotype of pDCs after 48 hours of culture in medium alone (Med), exogenous cytokines (GM-CSF, IL-3), and CpG-C was assessed by flow cytometry. Filled histograms represent specific staining; open histograms, isotype-matched controls. Inset values indicate mean fluorescence intensities over all viable pDCs. Data are from one representative of 10 independent experiments each from different donors. (B) pDC maturation after 48 hours of culture in medium alone (Med) or with GM-CSF, IL-3, and CpG-C compared with ex vivo pDCs. The specific mean fluorescence intensity (MFI) of CD86, ICSOL, OX40L, and HLA-DR is over all viable cells. Data represent 10 independent experiments each from different donors. Error bars represent median. **P < .005; *P < .05; n.s. indicates not significant. (C) mRNA expression of T cell–derived cytokines after priming with pDCs activated for 48 hours with GM-CSF, IL-3, and CpG-C. GM-CSF pDCs induced higher IFN-γ and less IL-4 and IL-10 mRNA in T cells, compared with IL-3 pDCs. mRNA expression values are normalized on the level of the housekeeping gene β-2-microglobulin (B2M). Data are the mean of 10 independent experiments each from different donors. Error bars represent SEM. **P < .05. *P < .005. (D) Protein expression of T cell–derived cytokines after priming with pDCs activated for 48 hours with GM-CSF, IL-3, and CpG-C. CD4 T cells primed with GM-CSF pDCs produced higher levels of IFN-γ compared with IL-3– and CpG-CpDCs. They produced also more TNF and less IL-4 and IL-10 compared with IL-3 pDCs. Data are the mean of 12 independent experiments, each from a different donor. Error bars represent SEM. **P < .05. *P < .005.