FIG 2 .

SLO and NADase mediate GAS cytotoxicity for macrophages. Cell culture supernatants were collected to measure the LDH released by macrophages at 0, 2, and 4 h after infection. Cytotoxicity is expressed as a percentage of the amount of LDH released by uninfected macrophages lysed with 10% Triton X-100. Shown are the mean values ± the standard errors of four independent experiments performed in triplicate. Values for all of the mutant strains were significantly different from those for strain 854 at the corresponding time points. Asterisks indicate other comparisons with statistically significant differences. **, P < 0.01; ***, P < 0.001.