Corresponding to the prompted increase in caspase-3 activity in PMNs infected with DT-X, PMNs treated by anti-Fas Ab, or untreated PMNs, KP-M1-infected PMNs activated less caspase-3 activity (p < 0.01 at 2, 4, and 6 h post-infection; Figure 4). This evidence concerns the gene CASP3 and infection.