Blocking of CD38 signaling inhibits LPS-induced IL-12 production in MDDCs and Th1 polarization of naive T cells. (A) iMDDCs, treated with LPS alone or in combination with either sCD38, anti-CD31 mAb (Moon-1), or control mAb (X63), were cultured for 48 hours and supernatants were harvested. IL-12 production was assessed by ELISA. Values (mean ± SE) of 5 independent experiments are reported as percentage of cytokine production compared with LPS-matured MDDCs (LPS-induced IL-12 [pg/mL]: 359.1 ± 143.9). (B) iMDDCs, treated with LPS alone or in combination with either sCD38, anti-CD31 mAb (Moon-1), or control mAb (X63), were cocultured with cord blood T cells. On day 12, intracellular staining of IFN-γ and IL-4 was performed. The numbers in each quadrant indicate the percentage of positive cells. One representative experiment of 5 performed is shown. (C) iMDDCs, treated with LPS alone or in combination with either sCD38, anti-CD31 mAb (Moon-1), or control mAb (X63), were cocultured with cord blood T cells. Secreted cytokines were measured by CBA assay. Cumulative values (mean ± SE) of 5 independent experiments are reported as percentage of cytokine production compared with LPS-matured MDDC-treated cord blood T cells (LPS-induced IFN-γ [pg/mL]: 2056.5 ± 734.1; LPS-induced IL-5 [pg/mL]: 278.5 ± 146).