Granulocyte-macrophage colony-stimulating factor increases l-arginine transport through the induction of CAT2 in bone marrow-derived macrophages

l-Arginine transport is crucial for macrophage activation because it supplies substrate for the key enzymes nitric oxide synthase 2 and arginase I. These enzymes participate in classic and alternative activation of macrophages, respectively. Classic activation of macrophages is induced by type I cytokines, and alternative activation is induced by type II cytokines. The granulocyte macrophage colony-stimulating factor (GM-CSF), in addition to inducing proliferation and differentiation of macrophages, activates arginase I, but its action on l-arginine transport is unknown. We studied the l-arginine transporters that are active in mouse primary bone marrow-derived macrophages (BMM) and examined the effect of GM-CSF treatment on transport activities. Under basal conditions, l-arginine entered mainly through system y+L (>75%). The remaining transport was explained by system y+ ( 10-...