mDCs are sufficient for CD4+ T cell activation and Th1-like polarization. (A) pDCs and mDCs were purified by positive selection using magnetic beads and incubated separately or together (both) with P. falciparum-iRBCs or uninfected RBCs at a ratio of 1:3 [DC:(i)RBC] for 3 h, harvested, and coincubated with autologous naïve CD4+ T cells at a ratio of 1:30 (DC:T cell) for 7 d. T cell proliferation was quantified by CFSE dilution, and cytokines were analyzed in the supernatants. (B) Purified mDCs were incubated with iRBCs at a ratio of 1:3 [DC:(i)RBC] or LPS for 24 h, washed, and analyzed with light microscopy. (Scale bar,10 µm.) (C) Purified mDCs were incubated with P. falciparum-iRBCs or uninfected RBCs at a ratio of 1:3 [DC:(i)RBC] for 3 h, harvested, and coincubated with autologous naïve CD4+ T cells at a ratio of 1:30 (DC:T cell) with isotype control or blocking antibodies for CD40L or IL-12p70 for 7 d. SD of triplicates from one experiment is shown (*P < 0.05 by Kruskal–Wallis test vs. iRBCs plus isotype control). One representative experiment of two is shown.