Cytokine expression in freshly isolated AMs and 18 h cultured AMs. RNA was extracted in freshly isolated (open bars) and 18 h cultured AMs (closed bars) to measure cytokine expression using Multiplex PCR (a). The ratio of the band density of each cytokine over the housekeeping gene, GAPDH, was calculated (b). Cultured AMs expressed significantly (*P<0.05) less IL-6, IL-1α, and TNF compared with freshly isolated AMs. Mean ±3 to 5 experiments. Cultured AMs express significantly (**P<0.01) less Arginase-2 than freshly isolated AMs (c). Mean ± 7 experiments. AMs, alveolar macrophage; GAPDH, glyceraldehyde-3-phosphate dehydrogenase.