BM-derived macrophages viability after infection with L. pneumophila. BM-derived macrophages from wild-type and Fas-deficient mice were prepared as described in materials and methods. The cells were infected with L. pneumophila at MOI of 1 and then kept in 5% CO2 or 5%CO2 plus hyperoxia. The viability of cells was examined 24 hours after the infection. The white column is the results of the wild-type mice whereas the filled column indicated results of Fas-deficient mice (n = 5).