FIG. 2.

IFN and ribavirin enhance anti-CD95-induced apoptosis in HepG2 cells. HepG2 cells were pretreated for 24 h with the indicated stimuli and then stimulated for 12 h with 0.25 μg of anti-CD95 per ml. Subsequently, nuclei were isolated by hypotonic lysis, stained with propidium iodide, and analyzed by flow cytometry for hypodiploid DNA content as an indicator of apoptosis. A total of 8,000 nuclei was counted per data point. The incidence of nuclei with hypodiploid DNA content is expressed as a percentage of the total number of nuclei. (A) IFN only; (B) ribavirin only; (C) 10 kU of IFN per ml plus ribavirin as indicated on the x axis. Values are means and standard deviations of triplicate determinations. For comparison, the same dose of anti-CD95 in combination with CHX would result in 90 to 100% apoptosis after 24 h.