CpG-STAT3 siRNA stimulates the immune activity of human dendritic cells in vitro. Cultured mDCs (A) or pDCs (B) were incubated for 48 hours in the presence of 500nM CpG-siRNAs targeting STAT3 or Luc (as a negative control). The surface expression of HLA-DR and CD86 immune activation markers on both DC populations was assessed by flow cytometry. (C-D) IL-12 expression in pDCs treated as described for panels A and B was evaluated in total RNA samples (C) or in cell-culture supernatants (D) using qPCR or Luminex assays, respectively. Presented are results averaged from 3 independent experiments and analyzed for statistical significance. Data are shown as means ± SEM (n = 3). ns indicates not significant. (E) STAT3 blocking in cultured human pDCs augments their immunostimulatory effect on T cells. Allogeneic CD3⁺ T cells were labeled using CFSE and incubated for 5 days at a 1:2 ratio with pDCs pretreated as indicated. T-cell expansion was assessed by CFSE dilution using flow cytometry.