Immunomodulatory properties of titanium dioxide nanostructural materials.

Although titanium dioxide (TiO2) nanostructural materials have been widely used in Biology and Medicine, very little is known about immunomodulation mechanism of these materials. Objectives of this study are to investigate in vitro immunomodulatory effects of TiO2. Immunosuppressant may lower immune responses and are helpful for the treatment of graft versus host diseases and autoimmune disorders. In this study, we used H2Ti3O7 titanium dioxide nanotubes (TNT) nanotubes along with commercial TiO2 nanoparticles (TNP) and TiO2 fine particles (TFP). We investigated the in vitro immunomodulatory effects of TNP, TNT, and TFP using mixed lymphocyte reaction (MLR). Suppression was studied by 3-(4, 5-dimethylthiazol-2yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay. Cytokine profile was measured by enzyme-linked immunosorbent assay (ELISA). The results from this study illustrated that the TiO2 nanostructural materials strongly suppressed splenocytes proliferation in MLR. For TNP and TNT, at 50 μg/ml suppression of 20%-25% and 30%-35%, respectively, and for TFP at 100 μg/ml suppression was 25%-30% was observed. Suppression of splenocytes proliferation in the presence of TNP, TNT, and TFP demonstrated that these nanostructural materials probably block T-cell-mediated responses in vitro. Our ELISA results confirmed that significantly lower levels of Th1 type cytokines (interleukin-2, interferon-γ) in the 48 h MLR culture supernatants. Our data suggest that TiO2 nanostructural materials suppress splenocytes proliferation by suppressing Th1 cytokines.