Macrophages (MPhis) exhibit functional heterogeneity and plasticity in the local microenvironment. Recently, it was reported that MPhis can be divided into proinflammatory MPhis (MPhi1) and anti-inflammatory MPhis (MPhi2) based on their polarized functional properties. Here, we report that nicotine, the major ingredient of cigarette smoke, can modulate the characteristics of MPhi1. Granulocyte-macrophage colony-stimulating factor-driven MPhi1 with nicotine (Ni-MPhi1) showed the phenotypic characteristics of MPhi2. Like MPhi2, Ni-MPhi1 exhibited antigen-uptake activities. Ni-MPhi1 suppressed IL-12, but maintained IL-10 and produced high amounts of MCP-1 upon lipopolysaccharide stimulation compared with MPhi1. Moreover, we observed strong proliferative responses of T cells to lipopolysaccharide-stimulated MPhi1, whereas Ni-MPhi1 reduced T cell proliferation and inhibited IFN-gamma production by T cells. These results suggest that nicotine can change the functional characteristics of MPhi and skew the MPhi1 phenotype to MPhi2. We propose that nicotine is a potent regulator that modulates immune responses in microenvironments.