Persistent immunotoxic effects of tributyltin in human natural killer cells can be reversed by interleukin 2

Effects of tri butyl tin acetate on dopamine biosynthesis and l-dopa-lnduced cytotoxicity in pc12 cells

The effects of tributyltin acetate (TBTA) on dopamine biosynthesis and L-3,4-dihydroxyphenylalanine (L-DOPA)-induced cytotoxicity in PC12 cells were examined. TBTA at concentrations of 0.1-0.2 microM inhibited dopamine biosynthesis by reducing tyrosine hydroxylase (TH) activity and TH gene expression in PC12 cells. TBTA at 0.1-0.4 microM also reduced L-DOPA (20-50 microM)-induced increases in dopamine content for 24 h in PC12 cells. TBTA at concentrations up to 0.3 microM did not affect cell viability. However, TBTA at concentrations higher than 0.4 microM caused apoptotic cytotoxicity. Exposure of PC12 cells to non-cytotoxic (0.1 and 0.2 microM) or cytotoxic (0.4 microM) concentrations of TBTA with L-DOPA (20, 50 and 100 microM) significantly increased the cell loss and the percentage of apoptotic cells after 24 or 48 h compared with TBTA or L-DOPA alone. These data suggest that TBTA inhibits dopamine biosynthesis and enhances L-DOPA-induced cytotoxicity in PC12 cells.

Effects of interleukins 2 and 12 on the levels of granzyme B and perforin and their mRNAs in tributyltin-exposed human natural killer cells

Natural killer (NK) cells are a subset of lymphocytes that are capable of killing tumor cells, virally infected cells and antibody coated cells. Tributyltin (TBT) is a toxic chemical used for various industrial purposes such as: slime control in paper mills, disinfection of circulating industrial cooling waters, anti-fouling agents, and the preservation of wood. TBT can be found in edible items such as fish. A previous study showed that a 1 h exposure of NK cells to TBT caused persistent inhibition of NK-cell ability to destroy tumor cells in the 24 and 48 h periods following exposure and that this loss of function could be significantly prevented and/or reversed if the NK-stimulatory interleukins (IL) 2 or 12 were present during the 24 and 48 h periods. We had also shown that TBT exposure was able to significantly decrease the protein and mRNA levels of the cytotoxic proteins, granzyme B and perforin, and the phosphorylation of cAMP-response-element-binding protein (CREB) under these conditions. In this study we address the effects of IL-2 and IL-12 on the TBT-induced decreases in NK-cell levels of the cytotoxic proteins, their mRNAs, and CREB phosphorylation. IL-2 appeared to prevent/reverse TBT-induced declines in perforin protein levels and the mRNA for perforin seen in the 24 h period following a 1 h exposure to 300 nM TBT. However, the TBT-induced decreases in the levels of perforin and perforin mRNA seen in the 48 h period following a 1 h exposure to TBT were not statistically significantly prevented/reversed by IL-2. Additionally, the TBT-induced decreases in granzyme B, granzyme B mRNA, and CREB phosphorylation were not statistically significantly reversed by either IL-2 or IL-12 after 24 or 48 h.