Vesicles from a CF isolate associates to a greater extent with lung cells compared to PA01 vesicles. FITC-labeled vesicles (2.5 μg per well) were incubated with confluent monolayers of approximately 5 × 104 A549 cells (A) or HBE cells (B) for indicated times at 37°C. Fluorescence associated with washed, solubilized cells was quantitated and correlated to vesicle amount using standard curves generated for vesicles from each strain. Experiments were done in triplicate, SEM is indicated for 2 to 7 separate experiments. At the 24 h time point, p < 0.001 for each data set.