Selective inhibitory effects of 50-nm gold nanoparticles on mouse macrophage and spleen cells

Nanoparticles (NP) are significant to multiple industrial processes, consumer products and medical applications today. The health effects of many different types of NP, however, are largely unknown. The purpose of this study was to test the effects of 50-nm gold NP coated with poly-N-vinylpyrrolidone (PVP) on mouse macrophage and spleen cells with and without lipopolysaccharide (LPS), testing the hypothesis that the NP would modulate immune responses without being overtly toxic. Gold NP had no effect on macrophage viability and, in the absence of LPS, they had no effect on tumor necrosis factor (TNF)-α production as measured by ELISA. The presence of LPS significantly increased the release of TNFα from the macrophages above no-treatment controls, but increasing gold NP concentration led to decreasing release of TNFα. The reactive oxygen species (ROS) produced by exposed macrophages were also reduced compared to untreated controls, both with and without LPS, suggesting some kind of oxygen radical scavenging. In splenocyte cultures, gold NP had no effect alone, but significantly reduced the release of interleukin (IL)-17 and TNFα triggered by LPS. These results suggest that the gold NP used here are not cytotoxic to immune cells at these concentrations, but may affect cellular responses to infection or inflammation by altering the balance of cytokines.