Figure 1: IL-6 and IL-8 secretions by polarized airway epithelial cells infected with normal and SCV strains are similar despite marked differences in infection levels. (A) Bacterial CFU recovered 48 h post-invasion from polarized Calu-3 cells infected with the S. aureus SCV strains CF07-S and CF1D-S and their normal counterparts CF07-L and CF1A-L, respectively. Significant differences between CFU recovered from cells for normal and SCV strains of each pairs are indicated (**, P < 0.01; ***, P < 0.001; unpaired t-test). Figures 1B and 1C show the concentrations of IL-6 and IL-8 in the basal compartment of Transwells seeded with polarized Calu-3 cells, respectively. Cells were either non-infected (untreated control), treated with dead bacteria (D.B.) or infected with the various strains CF07-L, CF07-S, CF1A-L and CF1D-S. The medium from the basal compartment of the Transwell was collected 48 h post-invasion for the measurement of IL-6 and IL-8 concentrations. Significant differences between the control and the infected conditions are shown (*, P < 0.05; **, P < 0.01; one-way ANOVA followed by the Dunnett’s post test). No difference between strains was revealed by a one-way ANOVA followed by the Tukey’s post test. Results are from three independent experiments performed in duplicate.