FIG. 7.
Effect of l-tryptophan or ferric citrate on the IFN-γ induced reduction in S. aureus infection of ECs. Monolayers of 2 × 105 ECs, cultured for 72 h in culture medium alone (open bars) or supplemented with 500 U/ml IFN-γ (closed bars) were exposed to 5 × 107 S. aureus for 1 h, washed, treated with lysostaphin, and cultured for an additional 23 h in culture medium without antibiotics. During cytokine stimulation, infection, and the postinfection culture periods, indicated concentrations of l-tryptophan (A) or ferric citrate (B) were present in the media. Values represent the means ± standard deviations of three (A) or two (B) experiments with ECs from different donors.