To further explore the influence of IL-4 post-stimulation on the L-arginine pathway and therefore on S.tm proliferation in macrophages, we infected IL-4 or IFNγ post-stimulated BMDM in L-arginine-depleted medium and studied the effects on the course of infection under these conditions and upon supplementation of L-arginine after establishment of infection and cytokine treatment. The gene discussed is IL4; the disease is infection.