FIG. 3.

Time dependence of maximal IL-8 secretion on the T. gondii inoculum. HeLa cell monolayers in 24-well plates were infected with 2.5 × 10⁵ (▾) or 1 × 10⁶ (●) tachyzoites/well, or left uninfected as controls (○), and incubated for 8 to 72 h. (A) IL-8 secretion. IL-8 concentrations were determined by ELISA. Data points represent means ± standard errors of the means (n = 4). IL-8 secretion at 48 and 72 h was significantly increased above controls (P < 0.02, Student’s paired t test). (B) Viable cell counts. The number of viable cells in the monolayers was determined by trypan blue dye exclusion following detachment of the cells with trypsin-EDTA. Values represent the means ± standard errors of the means of three or more determinations.