Figure 1: Treatment of a rat alveolar macrophage cell line with IFN- γ or IL-4 polarizes them into the M1 or M2 state, respectively. NR8383 cells were treated with either IFN-γ or IL-4 for 72 hours. Gene expression of Arg1 and iNOS were quantified by qPCR. Cells treated with IFN-γ demonstrated a marked decrease in the ratio of Arg1 to iNOS expression, suggesting a shifting of the population toward the M1 activation state. Cells treated with IL-4 had a marked increase in the ratio of Arg1 to iNOS ratio, suggesting a shift of the population to the M2 state. Data presented as a ratio of the fold change on a logarithmic scale (mean ± SEM, n=4).