Immunotoxicity and Sensitizing Capacity of Metal Compounds Depend on Speciation

Immunotoxicity of metal compounds is an issue of great importance due to the recent industrial application of metals with unknown toxicity on the immune system and the discovery of metal intermediary compounds not sufficiently studied yet. In this report we show results of our study on the immunotoxicity of the following metals: the Platinum group elements (Platinum, Palladium, Rhodium), Titanium and Arsenic. We applied functional and non functional assays and investigated both innate and adaptive immune systems, in particular, cell proliferation, cytokine production by PBMCs and O⁻₂ production by neutrophils. We obtained the following results: only some Ti compounds (Titanocene, Ti ascorbate and Ti oxalate) show immunotoxicity. Trivalent As compounds (Sodium arsenite and tetraphenyl arsonium chloride) are more immunotoxic than the other investigated As compounds. Genotoxicity of Pt group compounds is in the following order: Pt < Rh < Pd. Immunotoxicity of Pt group compounds is in the following order: Pd < Pt < Rh. Lymphocytes and macrophages show a different reaction of neutrophils to metal toxicity. We can conclude that these studies show that metal immunotoxicity depends on speciation. In general speciation provides additional and often essential information in evaluating metal toxicity. However, there are many difficulties in applying speciation in investigating toxico-kinetic aspects to many metals, mainly due to the lack of information about the existence and significance of species and to the lack of analytical methods for measuring species in biological samples.