Bacterial numbers in the lungs of mice with L. pneumophila. Wild-type and Fas-deficient mice were infected intratracheally with approximately 106 CFU/mouse of L. pneumophila. The mice of hyperoxia group were kept in hyperoxic condition. The lungs were removed and homogenized at 48 hours after the infection. The lung homogenates were incubated on BCYE-α agar after serial 10-fold dilution for 4 days. The white column represents the bacterial number in the lungs of wild-type mice whereas the filled column represents the results of Fas-deficient mice (n = 5).