A phoP∷Tn10 mutant killed fewer U-937 macrophages
than wild-type S. typhimurium by 20 or 24 hr after
infection. (A) Suspended and adherent cells were
harvested and processed for FACS 20 hr after infection. The percentage
of TUNEL-positive events is shown. (B) LDH release was
measured 24 hr after infection. Results are presented as the percent
cell death, where 100% is the amount of LDH in uninfected lysed cells.
lysed, uninfected lysed; WT, wild-type; phoP,
phoP∷Tn10 mutant; spiA, spiA∷Tn5
mutant.