FIG. 3.

Effect of caspase inhibition on HCT-8 cell apoptosis. Monolayers of HCT-8 cells were treated with a pan-caspase inhibitor or an inactive analog peptide 1 h prior to infection with C. parvum and continuously cultured in itspresence thereafter. The percentage of all cells (infected or noninfected) that were apoptotic was measured by counting cells showing nuclei condensation from at least three fields of each sample. Shown are results for cultures infected with C. parvum only (▴), cultures treated with negative peptide only (⋄), cultures treated with negative peptide and C. parvum infected (⧫), and cultures treated with pan-caspase inhibitor and C. parvum infected (▪). Mock-infected cells and cells treated with the pan-caspase inhibitor had less than 3% apoptosis at all time points (data not shown). Results are the medians ± ranges from four replicates in one of two separate experiments. An asterisk indicates that the percentage of apoptosis is significantly different between cells treated with C. parvum alone and cells treated with pan-caspase inhibitor and C. parvum at indicated time points.