The effects of nano-silver on the proliferation and cytokine expression by peripheral blood mononuclear cells.

Silver could prove to be a valuable alternative raw material for antibiotics and disinfectants as it is relatively free of adverse effects. Nano-silver is now been put to practical use in commonly used items, such as, clothes, electric home appliances, and electronic industry, but has not been widely applied in the medical or pharmacological fields. This study was designed to investigate the effects of nano-silver on the production of cytokines by and on the proliferation of peripheral blood mononuclear cells (PBMCs). In addition, we investigated the potential cytotoxic effects of nano-silver on PBMCs. PBMCs from healthy human volunteers were stimulated with 5 mug/ml phytohaemagglutinin (PHA) in the presence of varying concentrations of nano-silver. PBMC proliferations were measured using an aqueous cell proliferation assay kit and supernatants were analyzed using enzyme-linked immunosorbent assays. Interleukin-5 (IL-5), interferon-gamma (INF-gamma), and tumor necrosis factor-alpha (TNF-alpha) protein levels were measured to determine the activation state of PBMCs. At levels of over 15 ppm, nano-silver was found to have a significant cytotoxic effect on PBMCs, and PHA-induced cytokine productions were significantly inhibited by nano-silver (IL-5: at 10 ppm, INF-gamma and TNF-alpha at 3 ppm). Although nano-silver had a cytotoxic effect at high concentration, nano-silver modulated cytokine production in a concentration-dependent manner. These experimental data suggest that nano-silver could be used to treat immunologic and inflammatory diseases.