Figure 1.

IFN-γ promotes the loss of chromosomal DNA. BMDM were pretreated with IFN-γ (100 units/ml) overnight and infected with BCG at MOI of 50 for 6 h. Cells were then fixed and stained with DAPI for microscopy (×400). Uninfected cells (Top left) show normal nuclear morphology. BCG-infected cells (Top right) show nuclear pyknosis (Arrows) typical of high-MOI cell death. Cells treated with IFN-γ prior to BCG infection (Bottom left) show near total loss of nuclear DAPI staining (Dashed arrows). The addition of Z-VAD-fmk 1 h prior to infection restored the nuclear morphology of BCG-infected cells treated with IFN-γ to that of cells infected with BCG in the absence of IFN-γ (Bottom right).