Fig. 1.

DCs phagocytose P. falciparum-iRBCs and up-regulate maturation markers and secretion of chemokines, but not cytokines. DCs were incubated with late-stage P. falciparum-iRBCs or uninfected RBCs at a ratio of 1:3 [DC:(i)RBC] for 24 h (A and D–G) or 1:3 [DC:carboxy-fluorescein succinimidyl ester (CFSE)-labeled (i)RBC] for 3 h (B and C) and analyzed for surface marker expression (A, D, and E), chemokine (F) and cytokine (G) secretion, or phagocytosis by FACS (B) and immunofluorescence microscopy (C). (A) DCs enriched by negative selection followed by positive selection for HLA-DR with magnetic beads from PBMCs were gated first by using forward scatter (FSC) and SSC, followed by selection of HLA-DR⁺ cells, and used for further analysis in B and D–G. (B and C) Phagocytosis of iRBCs is observed as CFSE-positive DCs. Data from one representative experiment of three are shown. An example of surface marker expression for one donor (D) and the analysis of seven (E and F) and eight (G) donors are shown (E–G), with each symbol representing results from one individual donor and experiment (*P < 0.05, **P < 0.01, and ***P < 0.001 by Friedman test vs. RBCs or control; line depicts grand mean).