Since metal (silver and gold) and metal oxide (TiO2, ZnO, SiO2) nanoparticles (NPs) are
widely used in diagnostics, therapeutics, and commercial products, specialized immuno-toxicity studies
are necessary to ensure their safe use in humans. In this article, we review the immunological toxicity of
engineered nanomaterials (ENMs), including metal oxide and metal NPs, and suggest animal models of
immunological disease suited to study the immunological effects of NPs. Administration of NPs at subtoxic
doses in animals with a background of immunological diseases, especially those with allergic or
inflammatory diseases, will accelerate our understanding of the precise immunotoxicity and immunestimulatory
effects of NPs following real-life exposures.