Growth factors upregulate arginase 1 in macrophages.

<p><b>A</b>) Induction of arg1 mRNA expression in macrophages exposed to recombinant growth factors. Uninfected and <i>L. donovani</i> infected hamster BMDMs were stimulated with EGF (100 ng/mL), FGF-2 (20 ng/mL), IGF-1 (100 ng/mL), PDGF (100 ng/mL), or IL-4 (25 IU/mL) for 24 hrs and the expression of arg1 mRNA determined by qRT-PCR. Shown is the mean and standard error of the mean (SEM; error bars) of 4 replicates from a single experiment that is representative of 2 independent experiments. <b>B</b>) Dose-dependent induction of arginase activity (urea production) in hamster BMDMs infected with <i>L. donovani</i> and exposed to 2-fold increasing concentrations of growth factors for 48 h. The concentration of the growth factors was: EGF: 12.5–100 ng/mL; FGF-2: 6.25–50 ng/mL; IGF-1: 50–400 ng/mL; and PDGF: 25–100 ng/mL. Shown is the mean and SEM of 2 replicates per dose that is representative of 4 independent experiments. *p<0.05; **p<0.01; ***p<0.001.