Figure 3.

Invasion of transformed airway epithelial cell lines by three strains of P. aeruginosa (two clinical isolates from patients with CF, 324 and 149, and a laboratory strain, PAO1). Cells were grown for 72 h at the temperature indicated in each figure (“Cells”). Bacteria were allowed to invade the epithelial cells for 3 or 4 h at the temperature indicated by “Invasion” on the figures. Bars indicate the means of the determinations, and error bars indicate the standard deviation of the mean. (A) Cells grown at 37°C, a temperature that inhibits membrane expression of ΔF508 CFTR (44); the invasion assay was carried out for 4 h at 37°C. Ingestion of P. aeruginosa by cells expressing wild-type CFTR was significantly higher than in cells lacking wild-type CFTR (P < 0.01, ANOVA). (B) Cells grown at 26°C and invasion assessed at 26°C. (C) Cells grown at 26°C and invasion assessed at 37°C. In both assays where cells were grown at 26°C to promote surface expression of ΔF508 CFTR (44), there were no significant differences (P > 0.2, ANOVA) in bacterial invasion among the cell lines for any P. aeruginosa strain tested.