In vitro comparative immune effects of different titanium compounds

Exposure to Ti compounds is today an occupational and environmental health hazard. Object of this study was to determine "in vitro" effects of different Ti salts on cultured human peripheral blood mononuclear cells (PBMC) proliferation and cytokine release. 10(-4) and 10(-7) M Ti compounds did not modify spontaneous PBMC proliferation. Ti dioxide (a biocompatible material and sunscreen component) did not exert effects on phytoemagglutinin (PHA) stimulated PBMC proliferation and on PHA stimulated IFN-gamma and TNF-alpha release from PBMC. On the other hand, 10(-4) M Ti oxalate (with wide industrial applications) and Ti ascorbate (used mainly in agriculture) inhibited about 70% the PHA stimulate PBMC proliferation; both these Ti compounds at 10(-4) and 10(-7) M concentrations significantly inhibited TNF-alpha release, while only Ti oxalate inhibited that of IFN-gamma. Titanocene (used in chemotherapy) did no exert effects on PBMC proliferation but markedly inhibited IFN-gamma and TNF-alpha release. On the whole, this study demonstrates that Ti dioxide is not immunotoxic; Ti oxalate shows marked immunotoxicity; titanocene exerts selective toxicity on cytokine release but not on PBMC proliferation, while Ti ascorbate affects TNF-alpha release from PBMC but not iFN-gamma release. In conclusion, the data show that immunotoxicity fo Ti depends on speciation.