Uptake of lucifer yellow, and live or heat-killed

L monocytogenes by HSCs. (A) Uptake of lucifer yellow by HSCs. Histograms: fluorescence intensity in a logarithmic scale (x-axis) was plotted against cell numbers (y-axis). Black histograms show the fluorescence of HSCs incubated with lucifer yellow at 37°C, and gray histograms show the fluorescence of HSCs incubated with lucifer yellow at 4°C (negative control). (B) Transmission electron microscopy reveals live cytosolic L monocytogenes beginning actin polymerization at 2 hours after infection (arrow; bar, 0.6 μm). (C) The 5d-HSCs were able to internalize heat-killed L monocytogenes, which were degraded in the lysosomal compartments (arrows; transmission electron microscopy; bar, 0.6 μm).