Modulation of the A549 phenotype by IFN-γ and/or TNF-α (in percentage). The A549 cells were incubated during 24 hrs with human recombinant IFN-γ (100 ng/ml, I100), TNF-α (50 ng/ml, T50) or both cytokines (50 ng/ml IFN-γ and 25 ng/ml TNF-α, I50/T25). The phenotype was analyzed by flow cytometry. The horizontal bars represent the medians of the results from seven independent experiments (each performed in triplicate). Mean values and medians are represented as dots and bars respectively. A value of P <0.05 was considered to be significant. * P < 0.05;** P < 0.01; *** P < 0.001.