Immunotoxicity of stainless-steel nanoparticles obtained after 3D printing.

This study aims to investigate the in vitro effects of nanoparticles (NPs) produced during the selective laser melting (SLM) of 316 L stainless steel metal powder on the immune response in a human blood model. Experimental data did not reveal effect on viability of 316 L NPs for the tested doses. Functional immune assays showed a significant immunosuppressive effect of NPs. There was moderate stimulation (117%) of monocyte phagocytic activity without significant changes in phagocytic activity and respiratory burst of granulocytes. A significant dose-dependent increase in the levels of the pro-inflammatory cytokine TNF-a was found in blood cultures treated with NPs. On the contrary, IL-8 chemokine levels were significantly suppressed. The levels of the pro-inflammatory cytokine IL-6 were reduced by only a single concentration of NPs. These new findings can minimise potential health risks and indicate the need for more research in this area.