FIG. 4.

CD14 does not play a role in phagocytosis of F. tularensis SchuS4 by human cells. Human dendritic cells and monocytes were infected with F. tularensis SchuS4 at a MOI of 50 in the presence of sCD14 and anti-CD14 or isotype-matched antibodies, respectively. Three hours after infection, the cells were lysed or stained for SchuS4 (green) and tubulin (red) and assessed for intracellular bacteria by enumerating bacteria in cell lysates or by confocal microscopy. (A to C) Addition of sCD14 had no effect on the uptake of viable SchuS4 by hDC (A). Furthermore, there were no significant differences in either the number of infected DC or the number of bacteria per cell among any group (B to D). (E to H) Blocking CD14 had no effect on the phagocytosis of viable F. tularensis SchuS4 by human monocytes (E). Further, there were no significant differences in either the number of monocytes infected or the number of bacteria per cell in any group (F to H). Data are representative of six experiments of similar design, using different donors. Values are means plus SEM (error bars).