Effect of iron chelation on IFN-γ-dependent growth inhibition of ST4 cells in vitro. (A) ST4 cells (0.25 × 106/mL) were cultured in triplicate in round-bottom 96-well plates in complete medium alone (▪) or in complete medium plus 1000 U/mL IFN-γ (□) in the presence of serially increasing doses of DFO (from 0 to 10 μM). After 48 hours, [3H]TdR uptake was measured. The results are expressed as the arithmetic mean of cpm plus or minus the standard deviation (SD). A representative experiment of 3 independently performed is shown. (B) ST4 cells were cultured in complete medium in the presence of 10 μM DFO with (gray histogram) or without (open histogram) 1000 U/mL IFN-γ for 24 hours. Apoptosis was measured using Tunel assay. Tunel staining profile of ST4 cells cultured in complete medium was used to set the marker of nonapoptotic cells (M). A representative experiment of 3 independently performed is shown.