Effects of iron on IFN-γ–induced apoptosis in serum-deprived T cells. ST4 cells were cultured for 24 hours in complete or serum-free medium, with or without 10 μM FeSO₄, and then further cultured in the absence (□) or presence (▪)of 1000 U/mL IFN-γ. After 24 hours, cells were recovered and stained with Tunel kit to evaluate IFN-γ–induced apoptosis. The number of apoptotic cells was determined by flow cytometric analysis. Percentage of DNA fragmentation is indicated. Results of 1 of 3 independently performed experiments are shown.