Interaction of T-2 toxin with bovine carrier erythrocytes: effects on cell lysis, permeability, and entrapment

In vitro effects of trichothecenes on human dendritic cells

The aim of this work was to study the in vitro effects of trichothecenes on human dendritic cells. Trichothecenes are mycotoxins produced by fungi such as Fusarium, Myrothecium, and Stachybotrys. Two aspects have been explored in this work: the cytotoxicity of trichothecenes on immature dendritic cells to determine IC 50 (inhibition concentration), and the effects of trichothecenes on dendritic cell maturation process. Two mycotoxins (T-2 and DON) known to be immunotoxic have been tested on a model of monocyte-derived dendritic cells culture. Cytotoxic effects of T-2 toxin and DON on immature dendritic cells showed that DON is less potent than T-2 toxin. The exposure to trichothecenes during dendritic cell maturation upon addition of LPS or TNF-alpha markedly inhibited the up-regulation of maturation markers such as CD-86, HLA-DR and CCR7. Features of LPS or TNF-alpha -mediated maturation of dendritic cells, such as IL-10 and IL-12 secretions and endocytosis, were also impaired in response to trichothecenes treatment. These results suggest trichothecenes have adverse effects on dendritic cells and dendritic cell maturation process.

Species-specific hemolysis of erythrocytes by T-2 toxin

The tricothecene mycotoxin, T-2 toxin interacts differently with mammalian erythrocytes. Pig, man, rabbit, guinea pig, horse, dog, rat, and mouse erythrocytes are all lysed to a varying degree by T-2 toxin. But cow, sheep, goat, buffalo, and deer erythrocytes are all resistant to hemolysis by T-2 toxin. Since erythrocytes from ruminant animals contain little or no phosphatidylcholine, perhaps the presence of phosphatidylcholine in the membrane is required for the hemolytic action of T-2 toxin. Sheep erythrocytes were used to encapsulate T-2 toxin further confirming the resistance of erythrocytes from animals with ruminant physiology to T-2 toxin lysis.

Cellular effects of T-2 mycotoxin on two different cell lines

The effects of T-2 toxin on protein synthesis, respiratory chain activity of the mitochondria, cell lysis and toxin-cell binding were compared in the toxin-sensitive bovine kidney cell line (MDBK) and in the toxin-resistant Chinese hamster ovary cell line (CHO). Protein synthesis and mitochondrial activity were 10-fold less sensitive in CHO cells as compared to MDBK (50% inhibition = 10-15 ng/ml vs. 1-1.5 ng/ml, respectively). Lytic activity, as determined by release of 51Cr from cells incubated at 4 degrees C, was not detected at 5 h or 24 h in either of the cell lines. However, at 24 h, CHO cells released less 51Cr than non-toxin-exposed controls, indicating that some membrane interaction does occur. Both cell lines equally bound [3H]T-2 toxin at 4 degrees C. At 37 degrees C, the MDBK cells take up twice as much [3H]T-2 toxin at 2 h and 6 h. These results indicate that T-2 toxin mediates a number of effects on the cell at the level of the membrane, protein synthesis and probably mitochondrial activity toward 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction.

Cytotoxic effect of T-2 mycotoxin on cells in culture as determined by a rapid colorimetric bioassay

We developed a colorimetric assay for determining metabolic activity (viability) of cells exposed to toxic agents. This system is based on the ability of mitochondrial enzymes in viable cells to modify a tetrazolium salt into a blue formazan product that can be detected spectrophotometrically at 570 nm. The assay works equally well for mammalian and insect cell lines and at 48 hr color formation is linear over a cell input range of 1.56-50 X 10(4) cells/ml. The inhibitory effects of T-2 mycotoxin on tetrazolium cleavage in L929 cells is comparable to that observed for protein and DNA synthesis (50% inhibition = 6-8 ng/ml). Using this system to analyze the lethal effect of T-2 toxin on cells from various animal species, it was found that bovine cells were the most sensitive (50% inhibition at 2.2 ng/ml) while hamster cells were the most resistant (50% inhibition at 26.2 ng/ml). Murine cells exhibited intermediate sensitivity (50% inhibition at 10.9 ng/ml). Variable toxin susceptibility was also observed among different cell types. Lymphocytes were 3-fold more sensitive to the T-2 inhibitory effects than comparable tissue culture cell lines. These data indicate that the colorimetric assay system could have broad applications in toxicological studies. Further, the observed differences in species sensitivity may provide insight into the primary mechanism of the T-2 toxin-cell interaction that ultimately leads to cell death.