Fig. 6. Expression of pro- and anti-inflammatory markers in classically and alternatively activated macrophages infected with influenza virus A/WSN/33. BMDMs were treated with 1 ng IFN-γ ml^− 1 or 4 ng IL-4 ml^− 1 for 16 h and then infected with 10 p.f.u. A/WSN/33 per cell (WSN). Cells were harvested at 48 h p.i. and expression of cellular markers was monitored by qRT-PCR. Results are representative of three independent experiments. (a, b) iNOS, (c, d) Arg-1, (e, f) TNF-α and (g, h) CD206. *P < 0.05; **P < 0.005; ***P < 0.001.