FIG. 4.

(A) Intracellular survival of Shigella in bone marrow-derived macrophages from C57BL/6 (squares) and GKO^−/− mice (triangles). Cells were either not activated (open symbols) or activated (solid symbols) with 100 U of gamma interferon per ml. Each datum point represents the mean of six independent determinations. (B) Intracellular survival of Shigella within J774 macrophagelike cells with (solid squares) or without (open squares) activation with gamma interferon (100 U/ml). Each datum point represents the mean of five independent determinations. (C) Intracellular survival of Shigella within L2 cells with (solid squares) or without (open squares) activation with gamma interferon (100 U/ml). Each datum point represents the mean of four independent determinations. Bars indicate one standard deviation.