Titanium dioxide nanoparticles (TiO2 NPs) are used in a wide range of applications. Although inhalation of NPs is one of the most important toxicologically relevant routes, experimental studies on potential harmful effects of TiO2 NPs using a whole-body inhalation chamber model are rare. In this study, the profile of lymphocyte markers, functional immunoassays, and antioxidant defense markers were analyzed to evaluate the potential adverse effects of seven-week inhalation exposure to two different concentrations of TiO2 NPs (0.00167 and 0.1308 mg TiO2/m3) in mice. A dose-dependent effect of TiO2 NPs on innate immunity was evident in the form of stimulated phagocytic activity of monocytes in low-dose mice and suppressed secretory function of monocytes (IL-18) in high-dose animals. The effect of TiO2 NPs on adaptive immunity, manifested in the spleen by a decrease in the percentage of T-cells, a reduction in T-helper cells, and a dose-dependent decrease in lymphocyte cytokine production, may indicate immunosuppression in exposed mice. The dose-dependent increase in GSH concentration and GSH/GSSG ratio in whole blood demonstrated stimulated antioxidant defense against oxidative stress induced by TiO2 NP exposure.

Aerosol Chemistry and Physics Research Group Institute of Chemical Process Fundamentals of the Czech Academy of Sciences 165 00 Prague Czech Republic

Department of Environmental Analytical Chemistry Institute of Analytical Chemistry of the Czech Academy of Sciences 602 00 Brno Czech Republic

Faculty of Medicine Slovak Medical University 833 03 Bratislava Slovakia

Faculty of Public Health Slovak Medical University 833 03 Bratislava Slovakia

Health Effects Laboratory Norwegian Institute for Air Research 2007 Kjeller Norway

Institute of Hygiene and Epidemiology 1st Faculty of Medicine Charles University and General University Hospital Prague 121 08 Prague Czech Republic

Laboratory of Molecular Morphogenesis Institute of Animal Physiology and Genetics Czech Academy of Sciences 602 00 Brno Czech Republic

Public Health Authority of the Slovak Republic Radiation Protection Department 82645 Bratislava Slovakia

RECETOX Faculty of Science Masaryk University 625 00 Brno Czech Republic

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