Fig. 9. (A) Kinetics of delivery of late endosome/lysosome-associated FDex into parasite-containing organelles formed after phagocytosis of metacyclic promastigotes. IFN--treated macrophages were incubated with FDex for 2 hours. After washings, they were chased either for 160 minutes or overnight before infection with L. amazonensis (LV79) or L. major (NIH173) metacyclic promastigotes. Macrophages were fixed and permeabilized at various times post-infection and the parasites they contained were counted after staining with either a mouse anti-Leishmania immune serum and a Texas Red conjugate or propidium iodide. For each experiment and at each time point, the percentage of FDex-positive, parasite-containing compartments was determined after counting about 100 organelles. Results are from a single experiment (LV79) or are the means + or - range of two experiments (NIH173). (B-E) Confocal microscopy of macrophages loaded with FDex, chased overnight in FDex-free medium and then infected with L. amazonensis metacyclics. Analysis was done 30 minutes (B,C) or 18 hours (D,E) after adding parasites. (B,D) and (C,E) are the differential interference contrast (DIC) and the fluorescence images of the same cells, respectively. Optical sections (0.3-0.5 µm thickness) are shown. The position of the parasites is indicated by arrows. Bar, 2 µm.