FIG. 5.

Quantitation of immunogold staining of F. tularensis RCI phagosomes 4 h after infection of human MDM. Histograms demonstrate the distribution of immunogold staining for CD63 (top) and cathepsin D (bottom) in phagosomes fixed 4 h after coincubation with the F. tularensis RCI and latex beads. Whereas the majority of both F. tularensis phagosomes and latex bead phagosomes acquired abundant staining for CD63, only latex bead phagosomes showed abundant staining for cathepsin D. Control sections incubated with isotypic control mouse myeloma Igs had <0.25 gold particles per μm of membrane. The experiment was performed twice, with similar results.