Uptake of liposomes in DCs. (A) DCs were treated with Lipo (middle panel) or M-Lipo (lower panel) at 37℃ for 2 h, respectively. Compared with Lipo, M-lipo particles were effectively taken up by the DCs. Untreated DCs served as a blank control. (B) Upper panel: untreated DCs; middle panel: DCs preblocked with 0.5% free mannose were treated with M-Lipo; lower panel: DCs were treated with M-Lipo. Images demosntrate that pre-incubation of DCs with 0.5% free mannose dramatically reduced the uptake of M-Lipo by DCs. Untreated DCs served as a blank control. (C) DCs were treated with M-Lipo (middle panel) or M/CpG-ODN-Lipo (lower panel) at 37℃ for 2 h, respectively. Untreated DCs served as a blank control. Images demonstrate that liposomal particles modified either with mannose alone or both mannose and CpG-ODN were effectively taken up by the DCs. Arrows indicate DCs engulfing liposomal particles modified with both CpG-ODN and mannose. Red signal, Dil-labeled mannose lipid; blue signal, DAPI nuclear stain; green signal, FITC-labeled CpG-ODN. Magnification, 200×.