Induction of apoptosis in endothelial cells by recombinant LIGHT. LIGHT induced apoptosis endothelial cells after preincubation with IFN-γ. Endothelial cells were incubated with medium, soluble LIGHT, TNF-α, cycloheximide alone or in combination with TNF-α or LIGHT for 24 hours. Thereafter harvested and analyzed for propidium iodide exclusion by FACS analysis. IFN-γ plus cycloheximide alone did not induce apoptosis (control). LIGHT combined with cycloheximide induced apoptosis in endothelial cells after pre-treatment with IFN-γ (Figure 6). IFN-γ alone had no effect on endothelial cells (not shown). The data represent the mean ± SD of three independent experiments performed.