FIG. 5.

Evaluation of the integrity of the host cell plasma membrane after L. monocytogenes infections. (A) LDH release by infected J774 cells. The release of LDH after infection of J774 cells by each strain was compared to total LDH determined after lysis with detergent. Values represent the mean ± the SD of three independent experiments. ✽, P < 0.05; ✽✽✽, P < 0.001 (as determined by unpaired t test compared to strain HG-L2003). (B) Cellular DNA staining by propidium iodide using mouse bone marrow-derived macrophages. The gray histogram represents the uninfected cells as negative control. The percentage of cells that were stained with propidium iodide is indicated. These data are representative of three experiments.