Inhibitory effect of Fusarium T2-toxin on lymphoid DNA and protein synthesis

Mechanism of Apoptosis in Porcine Ovarian Granulosa Cells Triggered by T-2 Toxin

T-2 toxin (T-2), an A-type mono mycotoxin produced by various Fusarium species, disrupts DNA/RNA and protein synthesis upon entering the body, resulting in pathological conditions in various tissues/organs and posing a significant threat to human and animal health. However, the mechanisms underlying its toxicity remain unclear. With the goal of learning how T-2 affects reproduction in animals, we utilized primary porcine ovarian granulosa cells (pGCs) as a carrier in vitro and constructed concentration models for analyzing cell morphology and RNA-sequencing (RNA-seq). Our findings showed that T-2 could influence pGCs morphology, induce cell cycle arrest, and promote apoptosis in a dose-dependent manner. The results of RNA-seq analyses indicated that a total of 8216 genes exhibited significant differential expression (DEG) following T-2 treatment, of which 4812 were observed to be down-regulated and 3404 were up-regulated. The DEGs following T-2 toxin treatment of pGCs had a notable impact on many metabolic pathways such as PI3K-Akt, Ras, MAPK, and apoptosis, which in turn altered important physiological processes. Gene set enrichment analysis (GSEA) indicated that the differences in the harmful effects of T-2 might be caused by the varying control of cellular processes and the pathway responsible for steroid metabolism. These results present further insights regarding the mechanism of T-2 action on sow reproductive toxicity, enhance our understanding of T-2 reproductive toxicological effects, and lay a theoretical foundation for the judicious prevention of T-2-induced reproductive toxicity.

Metabolic profiling as a powerful tool for the analysis of cellular alterations caused by 20 mycotoxins in HepG2 cells

Mycotoxins are secondary fungal metabolites which exhibit toxic effects in low concentrations. Several mycotoxins are described as carcinogenic or immunosuppressive, but their underlying modes of action especially on molecular level have not yet been entirely elucidated. Metabolic profiling as part of the omics methods is a powerful tool to study the toxicity and the mode of action of xenobiotics. The use of hydrophilic interaction chromatography in combination with targeted mass spectrometric detection enables the selective and sensitive analysis of more than 100 polar and ionic metabolites and allows the evaluation of metabolic alterations caused by xenobiotics such as mycotoxins. For metabolic profiling, the hepato-cellular carcinoma cell line HepG2 was treated with sub-cytotoxic concentrations of 20 mycotoxins. Moniliformin and citrinin significantly affected target elements of the citric acid cycle, but also influenced glycolytic pathways and energy metabolism. Penitrem A, zearalenone, and T2 toxin mainly interfered with the urea cycle and the amino acid homeostasis. The formation of reactive oxygen species seemed to be influenced by T2 toxin and gliotoxin. Glycolysis was altered by ochratoxin A and DNA synthesis was affected by several mycotoxins. The observed effects were not limited to these metabolic reactions as the metabolic pathways are closely interrelated. In general, metabolic profiling proved to be a highly sensitive tool for hazard identification in comparison to single-target cytotoxicity assays as metabolic alterations were already observed at sub-toxic concentrations. Metabolic profiling could therefore be a powerful tool for the overall evaluation of the toxic properties of xenobiotics.

T-2 toxin induces cytotoxicity and disrupts tight junction barrier in SerW3 cells

T-2 toxin, which is produced in grain and grain products as a secondary metabolite by Fusarium species, is also potentially dangerous for human health. Up to date, no study was reported the cytotoxicity of T-2 toxin on SerW3 cells in the perspective of junctional barriers. This study focused on revealing the cytotoxic effects of T-2 on Sertoli cells associated with cell junctional barriers. In the present study, SerW3 cells were exposed to T-2 toxin at 12, 120 and 1200ng/ml doses for 24 and 48h. Cytotoxicity tests including cell viability (MTT), lactate dehydrogenase (LDH) cytotoxicity test and trypan blue exclusion assay were performed. Occludin, ZO-1, N-cadherin and β-catenin were immunolabelled, expressions of occludin and N-cadherin were determined by western blotting. SerW3 cell barrier integrity was measured by transepithelial electrical resistance (TEER). Cytotoxicity caused by T-2 toxin increased in a dose dependent manner, expressions of proteins and TEER measurement decreased. This study may underlie the early targets of T-2 toxin on SerW3 cells mimicking blood-testis barrier in vitro.

Revisión: Implicaciones toxicológicas y nutricionales de la toxina T-2 / Review: Toxicological and nutritional implications of T-2 toxin

Trichothecenes are mycotoxins produced by species of the genus Fusarium. These toxins are associated with health problems in humans and animals. The most common trichothecenes in cereals are deoxynivalenol, HT-2 toxin, diacetoxyscirpenol, nivalenol, neosolaniol and T-2 toxin; the latter is the most widely studied because it is easy to produce in the laboratory. The effects of T-2 toxicosis include dermatonecrosis, reduced body weight and efficiency of food utilization, severe diarrhoea, haemorrhage, necrosis of the upper alimentary tract, anaemia, immuno suppression ; and in birds, poor feathering. This paper reviews the latest information about the occurrence, chemical characteristics, toxicity, metabolic alterations, biotransformation and detoxifi cation methods of the T-2 toxin.

Systemic Metabolic Responses of Broiler Chickens and Piglets to Acute T-2 Toxin Intravenous Exposure

The aim of this study is to thoroughly investigate the toxicity mechanism of mycotoxin T-2 toxin and to further understand the endogenous metabolic alterations induced by T-2 toxin. To achieve this, a nuclear magnetic resonance (NMR)-based metabonomics approach was used to analyze the metabolic alterations induced by a single intravenous injection of T-2 toxin (0.5 mg/kg of body weight) in piglets and broiler chickens. A range of metabolites in the plasma, liver, kidney, and spleen of broiler chickens and plasma of piglets was changed following T-2 toxin injection. For example, a rapid increase of amino acids together with a significant reduction of glucose and lipid occurred in the plasma of broiler chickens and piglets following T-2 toxin treatment. A significant accumulation of amino acids and modulated nucleotides were detected in the liver, kidney, and spleen of T-2 toxin-treated broiler chickens. These data indicated that T-2 toxin caused endogenous metabolic changes in multiple organs and perturbed various metabolic pathways, including energy, amino acid, and nucleotide metabolism, as well as oxidative stress. We also observed elevated levels of tryptophan in the T-2 toxin-treated broiler chickens, which may explain the reported neurotoxic effects of T-2 toxin. These findings provide important information on the toxicity of T-2 toxin and demonstrate the power of the NMR-based metabonomics approach in exploring the toxicity mechanism of xenobiotics.

The toxicity of acute exposure to T-2 toxin evaluated by the metabonomics technique

T-2 toxin is a common contaminant in grains and animal feedstuff, which becomes an increasing threat to human and animal health due to its high toxicity. Investigating the systemic effects of T-2 toxin is important to evaluate the toxicity and facilitate the assessment of food safety. In our investigation, rats were treated with a single dose of T-2 toxin at dosage levels of 0, 0.5, 2.0 and 4.0 mg kg(-1) body weight via gavage. The metabolic profiles of body fluids and multiple organs were obtained by NMR spectroscopy and analyzed by multivariate data analysis methods. The results showed that low and moderate doses of T-2 toxin only influenced the urinary metabonomes, while a high dose of T-2 toxin induced metabolic alterations in urine and multiple organs. These changes included alterations in the levels of membrane metabolites, TCA cycle intermediates, a range of amino acids, nucleosides and nucleotides. T-2 toxin exposure impaired spleen function, causing immunotoxicity, and inhibited protein and DNA biosynthesis. In addition, T-2 toxin also caused oxidative stress and disturbance in energy metabolism and gut microbiome. Our work provided a comprehensive insight into T-2 toxicity and revealed the great potential of metabonomics in assessing the impact of a toxic compound.

Comparison of the inhibition of deoxynivalenol and T-2 toxin on bovine and porcine platelet function

A platelet model system has been used to investigate the inhibitory effects of deoxynivalenol (DON, vomitoxin) and T-2 toxin, alone and in combination. In both bovine and porcine systems, the most dramatic effect observed was the instability in the platelet aggregates formed in the presence of the mycotoxins. Bovine platelets were more sensitive to the inhibitory effects of both of the mycotoxins than porcine platelets and in both species T-2 toxin was a more effective platelet inhibitor than DON. The mycotoxins may inhibit platelet function by a similar mechanism since an additive inhibitory response was observed when DON and T-2 toxin were added together to platelet suspensions.

T-2 toxin contamination in grains and selenium concentration in drinking water and grains in Kaschin-Beck disease endemic areas of Qinghai Province

It has been strongly suggested that two factors are involved in the development of Kaschin-Beck Disease (KBD), namely grains contamination with T-2 toxin and selenium deficiency. So our team undertook a survey about grains and drinking water in three rural KBD endemic villages and one non-KBD village in Qinghai Province. The level of T-2 toxin contamination in 364 grain samples was assayed using an ELISA kit. The selenium concentration in these grains and 15 drinking water samples from three KBD endemic villages were determined using the 2,3-diaminonaphthalene fluorometric assay. The results revealed that the level of T-2 toxin contamination in the samples from three KBD endemic villages was relatively high with an average level of 78.91 ng/g in wheat and 47.47 ng/g in flour. The T-2 toxin level in samples from the non-KBD village (12.23 ng/g) was significantly lower than that of local grains from the three KBD endemic villages. The average selenium content in wheat and flour from KBD areas was 0.0045 and 0.0067 μg/g, respectively. The selenium concentration in local grain samples was significantly lower than that in samples from the non-KBD village (0.0604 μg/g). In addition, the selenium concentration in drinking water from three KBD endemic villages was also low (0.156 μg/L). These results support a potential role of T-2 toxin contamination and selenium deficiency in KBD. Compared with non-KBD endemic areas, health hazards in grains and in the environment of KBD endemic areas were observed.

Comparison of the inhibitory effect of T-2 toxin on bovine platelet function with that of other known platelet inhibitors

The inhibitory effects of T-2 toxin on bovine platelet function and thromboxane A(2) production were compared with those of the known inhibitors of human platelet function, acetylsalicylic acid, dipyridamole and verapamil. T-2 toxin (1 × 10(-3)M) effectively inhibited bovine platelet aggregation (33.2-64.3%), whereas neither acetylsalicylic acid nor dipyridamole did so. T-2 toxin appeared to be a less effective inhibitor of platelet aggregation than the calcium channel blocker, verapamil. T-2 toxin (1 × 10(-3)M) added to platelet suspensions together with verapamil, produced an additive inhibitory response. T-2 toxin (2.5 × 10(-4)M) effectively inhibited the release of thromboxane A(2) from ADP-stimulated bovine platelets as did acetylsalicylic acid and verapamil but not dipyridamole. T-2 toxin appears to inhibit bovine platelets by a biochemical mechanism distinct from that of the other inhibitors.

Evaluation of protective efficacy of CC-2 formulation against topical lethal dose of T-2 toxin in mice

T-2 toxin is the type-A trichothecene and a common contaminant of food and cereals, produced by Fusarium species. T-2 toxin easily penetrates skin due to its lipophilic nature and causes skin irritation and blisters in humans. Physical protection of the skin and airway is the only proven effective method of protection. To date, no chemical antidotes are available to prevent T-2 induced lethality. In the present study, we evaluated the protective efficacy of 20% N,N'-dichloro-bis(2,4,6-trichlorophenyl) urea (CC-2) formulation against lethal topical exposure dose of T-2 toxin in mice. None of the animals exposed to only T-2 toxin at lethal dose of 2 and 4 LD50 (11.8 and 23.76 mg/kg body weight) survived beyond 36 and 16 h, respectively. CC-2 application at 5 and 15 min post-exposure protected mice 100% from lethality at 2 LD50. Survival rate was 100% and 50% at 4LD50 dose if CC-2 was applied dermally within 5 and 15 min post-exposure. Recovery profile of surviving animals after 2LD50 T-2 toxin exposure at 1, 3, 7, and 14 days was assessed in terms of hepatic GSH, lipid peroxidation, serum ALP, ALT and AST. Hepatic lipid peroxidation significantly increased in all groups exposed to T-2 toxin by 3 day but normalized by day 7. A delayed GSH depletion was noted in surviving animals on day 7 but recovered by day 14. ALT and AST levels were elevated in all CC-2 protected mice on day 1 and normalized by day 3. ALP level decreased till day 7 in all protected groups. The biochemical variables recovered to control values by 14th day. GC-MS analysis after in vitro interaction of CC-2 formulation with T-2 toxin had shown that nearly 86% of T-2 toxin is decontaminated in 5 min but 8-10% of T-2 toxin was still present even after 60 min of interaction. Results of our study suggest that CC-2 may be an effective dermal decontaminant against lethal topical exposure of T-2 toxin.

Bioactive metabolites from Phoma species, an endophytic fungus from the Chinese medicinal plant Arisaema erubescens

Through bioassay-guided fractionation, the EtOAc extract of a culture broth of the endophytic fungus Phoma species ZJWCF006 in Arisaema erubescens afforded a new α-tetralone derivative, (3S)-3,6,7-trihydroxy-α-tetralone (1), together with cercosporamide (2), β-sitosterol (3), and trichodermin (4). The structures of compounds were established on the basis of spectroscopic analyses. Compounds 1, 2, and 3 were obtained from Phoma species for the first time. Additionally, the compounds were subjected to bioactivity assays, including antimicrobial activity, against four plant pathogenic fungi (Fusarium oxysporium, Rhizoctonia solani, Colletotrichum gloeosporioides, and Magnaporthe oryzae) and two plant pathogenic bacteria (Xanthomonas campestris and Xanthomonas oryzae), as well as in vitro antitumor activities against HT-29, SMMC-772, MCF-7, HL-60, MGC80-3, and P388 cell lines. Compound 1 showed growth inhibition against F. oxysporium and R. solani with EC₅₀ values of 413.22 and 48.5 μg/mL, respectively. Additionally, compound 1 showed no cytotoxicity, whereas compound 2 exhibited cytotoxic activity against the six tumor cell lines tested, with IC₅₀ values of 9.3 ± 2.8, 27.87 ± 1.78, 48.79 ± 2.56, 37.57 ± 1.65, 27.83 ± 0.48, and 30.37 ± 0.28 μM, respectively. We conclude that endophytic Phoma are promising sources of natural bioactive and novel metabolites.

T-2 toxin induces degenerative articular changes in rodents: link to Kaschin-Beck disease

Osteoarthritis (OA) is a degenerative joint disease that is characterized by joint pain and a progressive loss of articular cartilage. Kaschin-Beck Disease is a form of endemic OA in China whose etiology is unclear, but epidemiological data indicate a possible link to trichothecenes mycotoxin exposure. In vitro, T-2 toxin, a trichothecenes mycotoxin, has been demonstrated to inhibit aggrecan synthesis and promote aggrecanase and pro-inflammatory cytokine production in cultured chondrocytes. To assess the effects of T-2 toxin on articular cartilage in vivo, Wistar rats were fed a diet containing T-2 toxin (100 ng/kg chow) for six and ten months. Following six months of T-2 toxin exposure, histopathological changes in femorotibial cartilage were characterized by chondrocyte degeneration/necrosis and loss, chondrocyte clones, and loss of proteoglycan staining of articular cartilage, sometimes involving the entire thickness of the cartilage in the tibial plateaus and femoral condyles. By ten months, in addition to these changes, there was evidence of cartilage fibration in some rats. In conclusion, T-2 toxin exposure in rats induced degenerative lesions in articular cartilage similar to spontaneous OA, lending support to an etiologic role of mycotoxins in Kaschin-Beck Disease. T-2 toxin-induced degenerative joint disease may be a useful model of metabolic polyarticular OA.

Development of qualitative and semiquantitative immunoassay-based rapid strip tests for the detection of T-2 toxin in wheat and oat

Novel qualitative as well as semiquantitative rapid strip tests for screening of T-2 mycotoxin in agricultural commodities were developed. Colloidal gold particles were coated with monoclonal anti-T-2 antibodies and used as detector reagent, indicating the strip test results by formation of up to two colored lines in a competitive assay format. The test line comprises a protein conjugate of the T-2 mycotoxin and the control line an antispecies-specific antibody to confirm the correct test development. To perform the test, 5 g of sample was extracted in a ratio of 1:5 with methanol/water (70:30) by shaking for 3 min and the extract directly used without further cleanup steps. The T-2 toxin lateral flow device (LFD) presented has a cutoff level around 100 microg/kg for naturally contaminated wheat and oat. The semiquantitative test may be used in the lower micrograms per kilogram range and allows for rapid semiquantitative photometric classification of the level of sample contamination. For both tests, results were obtained within 4 min. The developed LFDs therefore allow for the first time fast and on-site screening for the determination of T-2 toxin in cereals.

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Investigation into virulence and mycotoxin formation of the dry rot causing pathogen Fusarium sambucinum on potatos 11 strains ofFusarium sambucinum were isolated from tubers with dry rot symptoms from three different depots in the Land Brandenburg and Saxony-Anhalt. All isolates produced diacetoxyscripenol in artificially infected potato tubers. Additionally, two isolates produced T-2 and HT-2 toxins as well. The virulence and mycotoxin formation of the isolates was dependent on the potato varieties 'Sieglinde' and 'Berber' used in the experiment. The amount of diacetoxyscripenol in diseased tissue was positively correlated with the virulence of theF. sambucinum isolate and the susceptibility of the potato variety as well.

Adverse effects of T-2 toxin on chicken lymphocytes blastogenesis and its protection with Vitamin E

T-2 toxin, a trichothecene mycotoxin that is produced by fusarium species, is prevalent mainly in cereal crops and poultry feed. One of the major effects of this toxin is immunomodulation. The effect of T-2 toxin on chicken lymphocyte proliferation in the presence of mitogens and the subsequent protection with Vitamin E in both fat and water soluble forms was studied using an MTT colorimetric assay. T-2 toxin was administered in concentrations ranging from 0 to 10ng/mL of lymphocytes in the presence of either concanavalin A (ConA) or phytohemagglutinine (PHA-M) at optimum concentration of 333ng/mL and a dilution of 1:160 for ConA and PHA-M, respectively. Lymphocyte proliferation in response to ConA and PHA-M mitogens was depressed at T-2 doses of 1ng/mL or higher (p<0.05). The proliferation was completely abolished at 10ng/mL when the toxin was added at 0 time, while it was decreased by 80% when the toxin was added to the lymphocytes after 24h. The addition of Vitamin E in the fat soluble form (alpha-tocopheryl acetate) did not exert any protection effect against the toxin when it was added at either 25 or 100microg. However, when the water soluble form (Trolox) was added at a concentration of (200microg) (equivalent to 100microM of alpha-tocopherol), it provided considerable protection (p<0.05) against T-2 toxin inhibition of lymphocyte proliferation. The difference in the effect between the two forms of Vitamin E might be related to their relative solubility in the culture media which in turn may affect their availability for protection.

In vitro cytopathic effects of mycotoxin T-2 on human peripheral blood T lymphocytes

The trichothecene mycotoxin T-2 is reported to exhibit immunotoxic activity. The potential presence of T-2 in foods renders it as public health hazard and its toxicity needs to be better understood. We investigated the in vitro effects of T-2 at sub-toxic (0.1 ng/ml) and toxic (10 ng/ml) levels on freshly isolated human peripheral blood lymphocytes (PBLs). We observed no direct influence on untreated PBLs. The toxic dose of T-2, however, totally inhibited phytohemagglutinin-induced T lymphocyte proliferation and caused early apoptosis that peaked after 8h of exposure. Both major T lymphocyte subsets (CD4+ and CD8+) were affected as they appeared to show a positive response to T-2 at 8h followed by their sharp reduction after 96 h. Further investigation on the naïve (CD45RA+) and memory (CD45RO+) subpopulations confirmed these observations and indicated that T-2 affected equally all the subpopulations studied, although PHA preferentially stimulated CD45RO+ T lymphocytes. Sub-toxic T-2 appeared to exhibit co stimulatory properties to PHA-stimulated cells. These results support the hypothesis that T-2 affects the activation-induced cell death mechanism of T lymphocytes.

Effects of trichothecene mycotoxins on eukaryotic cells: A review

The major products of the trichothecene mycotoxin biosynthetic pathway produced in a species- and sometimes isolate-specific manner by cereal-pathogenic Fusarium fungi include T-2 toxin, diacetoxyscirpenol, deoxynivalenol and nivalenol. This paper briefly reviews the major effects of such trichothecenes on the gross morphology, cytology and molecular signalling within eukaryotic cells. The gross toxic effects of select trichothecenes on animals include growth retardation, reduced ovarian function and reproductive disorders, immuno-compromization, feed refusal and vomiting. The phytotoxic effects of deoxynivalenol on plants can be summarized as growth retardation, inhibition of seedling and green plant regeneration. Trichothecenes are now recognized as having multiple inhibitory effects on eukaryote cells, including inhibition of protein, DNA and RNA synthesis, inhibition of mitochondrial function, effects on cell division and membrane effects. In animal cells, they induce apoptosis, a programmed cell death response. Current knowledge about the eukaryotic signal transduction cascades and downstream gene products activated by trichothecenes is limited, especially in plants. In mammalian cells, certain trichothecenes trigger a ribotoxic stress response and activate mitogen-activated protein kinases. DON mediates the inflammatory response by modulating the binding activities of specific transcription factors and subsequently inducing cytokine gene expression. Several genes are up-regulated in wheat in response to trichothecene mycotoxins; the significance, if any, of these genes in the host response to trichothecenes has yet to be elucidated.

Gene expression profiles in pregnant rats treated with T-2 toxin

Pregnant rats on day 13 of gestation were treated orally with T-2 toxin at a single dose of 2 mg/kg and sacrificed at 24 hours after treatment. Histopathologically, apoptosis was increased in the liver, placenta and fetal liver. Microarray analysis was performed to examine the gene expression in the liver, placenta, and fetal liver. The results of microarray analysis showed that the changes in the expression of apoptosis genes, metabolic enzymes and oxidative stress-related genes were detected in these tissues. Suppression of phase I and II enzymes-related genes expression in the liver, and suppression of phase II enzymes-related genes expression in the placenta and fetal liver were observed. Semiquantitive RT-PCR analysis also showed the same results as those of microarray analysis. From the results of microarray analysis and histopathological examination, T-2 toxin seems to induce oxidative stress in these tissues, following the changes in metabolism-related genes expression. These changes may alter the intracellular environments resulting in the induction of apoptosis. Further studies on the gene expression profiles at the earlier time point are necessary to clarify the detailed mechanisms of T-2 toxin-induced toxicity in pregnant rats.

Comparative cytotoxicity of deoxynivalenol, nivalenol, their acetylated derivatives and de-epoxy metabolites

The cytotoxicity of the de-epoxy metabolites of trichothecenes nivalenol (NIV) and deoxynivalenol (DON) was determined and compared with the cytotoxicity of the respective toxin with an intact epoxy group and their acetylated derivatives. The cytotoxic effects was determined by using the 5-bromo-2'-deoxyuridine (BrdU) incorporation assay assessing DNA-synthesis. The toxicity of NIV and DON expressed as the concentration inhibiting 50% of the DNA synthesis (IC(50)), was occurring at similar micromolar concentrations (1.19+/-0.06 and 1.50+/-0.34 microM). The toxicity of fusarenon X (4-acetyl NIV) in the assay was similar to the toxicity of NIV, and the toxicity of 15-AcDON was equal to the toxicity of DON. 3-AcDON was less toxic than DON and 15-AcDON. The IC(50) value for de-epoxy DON was 54 times higher in the assay than the IC(50) for DON, while the IC(50) of de-epoxy NIV was 55 times higher than the IC(50) for NIV. The results verify previous findings that the de-epoxidation is a detoxification reaction.

Therapy and prophylaxis of inhaled biological toxins

This review highlights the current lack of therapeutic and prophylactic treatments for use against inhaled biological toxins, especially those considered as potential biological warfare (BW) or terrorist threats. Although vaccine development remains a priority, the use of rapidly deployable adjunctive therapeutic or prophylactic drugs could be life-saving in severe cases of intoxication or where vaccination has not been possible or immunity not established. The current lack of such drugs is due to many factors. Thus, methods involving molecular modelling are limited by the extent to which the cellular receptor sites and mode of action and structure of a toxin need to be known. There is also our general lack of knowledge of what effect individual toxins will have when inhaled into the lungs - whether and to what extent the action will be cell specific and cytotoxic or rather an acute inflammatory response requiring the use of immunomodulators. Possible sources of specific high-affinity toxin antagonists being investigated include monoclonal antibodies, selected oligonucleotides (aptamers) and derivatized dendritic polymers (dendrimers). The initial selection of suitable agents of these kinds can be made using cytotoxicity assays involving cultured normal human lung cells and a range of suitable indicators. The possibility that a mixture of selected antibody, aptamer or dendrimer-based materials for one or more toxins could be delivered simultaneously as injections or as inhaled aerosol sprays should be investigated.

Cytotoxicity assays for mycotoxins produced by Fusarium strains: a review

Mycotoxins are naturally occurring toxic secondary metabolites of fungi that may be present in food and feed. Several of these mycotoxins have been associated with human and animal diseases. Fusarium species, found worldwide in cereals and other food types for human and animal consumption, are the most important toxigenic fungi in northern temperate regions. The overall economical loss and the detrimental health effects in humans and animals of mycotoxin contamination are enormous and therefore, rapid screening methods will form an important tool in the protection of humans and animals as well as to minimize economical losses by early detection. An overview of methods for the determination of cytotoxicity and the application of such bioassays to screen solid fungal cultures, cereals, respectively, food/feedstuffs for the presence and toxic potential of Fusarium mycotoxins is presented. Various cell lines including different endpoints of toxicity using vertebrate cells and the predictive value of the in vitro assays are reviewed. Bioassays are compared with existing chemical analytical methods and the possibilities and limitations of such systems are discussed. The review is based on 149 references.

Superinduction of TNF-alpha and IL-6 in macrophages by vomitoxin (deoxynivalenol) modulated by mRNA stabilization

Vomitoxin (VT or deoxynivalenol), a trichothecene, superinduces proinflammatory cytokine gene expression in vitro and in vivo. To better understand the underlying molecular mechanisms for this observation, post-transcriptional effects of VT on TNF-alpha and IL-6 gene expression were studied in lipopolysaccharide (LPS)-stimulated macrophage RAW 264.7 cells. VT was found to enhance both TNF-alpha and IL-6 protein secretion in the presence of LPS. Upon addition of the transcriptional inhibitor, 5,6-dichloro-1-beta-D-ribofuranosyl benzimidazole (DRB), secretion of both cytokines was inhibited. Using Northern analysis, the mRNA stabilities of TNF-alpha and IL-6 were studied in DRB-treated cells exposed to VT and LPS in both asynchronous and delayed synchronous modes. In the asynchronous model, cells were first incubated with LPS for 2 h, and then the medium was removed and replaced with medium containing DRB and VT. In the delayed synchronous model, cells were pretreated with LPS for 2 h and then DRB and VT were added to the culture. TNF-alpha and IL-6 mRNA were rapidly stabilized by VT (100 and 250 ng/ml) in both asynchronous and delayed synchronous models. In the asynchronous model, TNF-alpha mRNA half-life was 25 min but this was extended in the presence of 100 and 250 ng/ml of VT to >3 h. VT also extended half-lives of IL-6 mRNA from 60 min to >3 h. In the delayed synchronous model, the half-lives for TNF-alpha and IL-6 mRNA of 1.3 and 1.5 h, respectively, were extended to >3 h upon incubation with 100 and 250 ng/ml VT. These results suggest that post-transcriptional control via enhancement of mRNA stability is likely to contribute to proinflammatory cytokine superinduction in macrophages by VT and other trichothecenes.

Cytotoxicity of four trichothecenes evaluated by three colorimetric bioassays

The application of cell culture technique for screening of low concentrations of Fusarium mycotoxins was examined. Three colorimetric bioassays were used to determine the cytotoxicity of the trichothecenes T-2 toxin (T-2), HT-2 toxin (HT-2), deoxynivalenol (DON) and nivalenol (NIV) to 3T3 mouse fibroblasts (3T3 cells). The bioassays assess DNA synthesis (incorporation of 5-bromo-2'-deoxyuridine; BrdU), metabolic activity (cleavage of 3-(4,5-dimethyltiazol-2-yl)-2,5-diphenyltetrazolium bromide; MTT) and cell membrane damage (release of lactate dehydrogenase; LDH), respectively. The BrdU bioassay was the most sensitive and the IC50 values (50% response compared to untreated cells) of T-2, HT-2, DON and NIV were 4.6, 13, 263 and 365 ng/ml, respectively. At the same toxin concentrations used in the BrdU bioassay, only T-2 and HT-2 were toxic enough to obtain IC50 values using the MTT bioassay. The IC50 values for T-2 and HT-2 were 12 and 68 ng/ml, respectively. When determined by the LDH bioassay, the IC50 values of T-2 and HT-2 were 18 and 42 ng/ml, respectively. At the tested concentrations, DON and NIV had a minor effect on the 3T3 cells when evaluated by the MTT and LDH bioassays. The BrdU bioassay in combination with 3T3 cells was found to be a suitable method for determination of trichothecene-induced toxicity at low concentrations.

Effect of dietary T-2 fusariotoxin concentrations on the health and production of white Pekin duck broilers

The effects of different dietary levels of T-2 toxin on production, biological, immunological, and pathological parameters of growing white Pekin ducks were studied to establish the "no effect" dietary concentration of, and "no effect" exposure time to, pure T-2 toxin. Day-old white Pekin ducks were randomly allotted to nine groups of 10 ducks each. One group served as a control, and no mycotoxin was added to its feed. The feeds of the experimental groups were supplemented with 0.2, 0.4, 0.6, 0.8, 1.0, 2.0, 3.0, and 4.0 mg purified T-2 toxin/kg, respectively, from Day 1 until Day 49 of the experiment. Dermatotoxic oral lesions developed in most experimental ducks within 2 d after the start of feeding T-2 toxin-contaminated feeds. The gradual disappearance of macroscopic signs indicated the development of tolerance in groups treated with the lower T-2 toxin content. No repair was found in the 3 and 4 mg/kg groups. Dietary concentrations of T-2 toxin below 0.4 mg/kg had no effect on the average weekly weight gain in the first 6 wk, but a severe decrease was found in the last week of the experiment. The 0.6 mg/kg dietary T-2 toxin had no effect on weight gain in the first 3 wk. At Week 4 and later, the weekly weight gain was significantly reduced, and the final live weight of this group was also significantly lower than that of the control. Dietary T-2 concentrations of 1 mg/kg and greater uniformly depressed growth rate. Only the 3 and 4 mg/kg groups refused feed during the first week. From Week 3 on, the feed intakes of the 0.6 to 4 mg/kg groups were usually less than that of the control group, indicating feed refusal. Serum and plasma chemical values and hematological parameters failed to show dose-dependent effects. The blastogenic response of lymphocytes to nonspecific and specific mitogens was distinctly impaired by the T-2 toxin at all levels in the feed. In the 3 and 4 mg/kg groups, the histological examination revealed lymphocyte depletion in the spleen and bursa of Fabricius.

In vitro inhibitory effects of antioxidants on cytotoxicity of T-2 toxin

T-2 toxin is a secondary fungal metabolite produced by various species of Fusarium. It is capable of killing cells by causing extensive damage to the cellular membrane. In this study, cytotoxicity of T-2 toxin in combination with different antioxidant materials, including vitamin C (vit. C), vitamin E (vit. E) and selenium (sel) was investigated in vitro using the neutral red cytotoxicity assay. Eleven primary and transformed cell lines established from different tissues were used in pre-test experiments to identify the most sensitive and resistant lines by measuring the half lethal concentration (LC(50)) of the toxin. Three cell lines including human gingival fibroblast (HGF), the most sensitive (LC(50)=0.25 ng/ml), human colorectal adenocarcinoma (SW742), the most resistant (LC(50)=5.5 ng/ml) and human hepatoma (HepG2), with median susceptibility (LC(50)=2 ng/ml) were selected to investigate the inhibitory effects of the antioxidant agents, on cytotoxicity of T-2 toxin. Our results demonstrated that co-incubation of cell lines with different concentrations of T-2 toxin and antioxidants decreased significantly, but did not totally inhibit, the cytotoxicity of T-2 toxin (P<0.001). These findings suggest that in addition to lipid peroxidation, which is inhibited by antioxidants, other unidentified mechanism(s) seem to be involved in cytotoxicity of T-2 toxin.

In vitro exposure of human lymphocytes to trichothecenes: individual variation in sensitivity and effects of combined exposure on lymphocyte function

The trichothecenes are mycotoxins produced by fungi of the genus Fusarium, which are commonly present in foods and feed of cereal origin. Owing to the lack of sufficient toxicological data for most of the trichothecenes, in vitro studies may contribute to risk assessments of these toxins. In the present report, human lymphocyte cultures were used to study the individual variation in sensitivity among humans and the effects on in vitro Ig production. Furthermore, proliferative responses of cells exposed to combinations of two of the toxins were studied. Four toxins, T-2 toxin, diacetoxyscirpenol (DAS), nivalenol (NIV) and deoxynivalenol (DON) were included in the study. All four of the tested trichothecenes effectively inhibited mitogen-induced lymphocyte proliferation. There were no statistically significant differences in sensitivity to the toxins between lymphocytes from female and male blood donors. The individual variation in sensitivity, evaluated as the range of IC50 values, was rather limited (within a factor of 3 to 4). Immunoglobulin production by pokeweed-stimulated human lymphocytes was also effectively inhibited with IC50 values similar to the IC50 values in the proliferation tests for DON and NIV. However, IC50 values for Ig synthesis in cultures exposed to T2 were approximately two to three times higher than the corresponding IC50 values found in the proliferation tests. At low levels of exposure, elevated Ig production was observed in lymphocyte cultures from four out of the five blood donors tested. This effect was most pronounced on IgA synthesis. Combinations of NIV with T2, DAS or DON resulted in additive toxicity in the lymphocyte proliferation test, while combinations of DON with T2 or DAS resulted in an inhibition that was slightly lower than what could have been expected from the inhibition produced by the individual toxins. In conclusion, the tested trichothecenes inhibited both proliferation and Ig production in human lymphocytes in a dose-dependent manner with limited variation in sensitivity between individuals. Enhanced Ig production was observed in cell cultures exposed to the lower doses of the toxins. Combined exposure to two of the toxins resulted mainly in additive or antagonistic effects, although synergistic effects cannot be excluded and should be further investigated. These findings indicate that the total intake of type A and B trichothecenes should be taken into account in risk assessments.

T-2 toxin-induced apoptosis in hematopoietic tissues of mice

We examined T-2 toxin-induced lesions in the bone marrow and splenic red pulp as many as 48 hr after oral inoculation with 10 mg/kg body weight of T-2 toxin in female ICR:CD-1 mice. Histopathologically, the bone marrow and splenic red pulp showed a significant hypocellularity. In the bone marrow, the number of myelocytes significantly decreased due to the loss of immature granulocytes, erythroblasts, and lymphocytes. The nuclei of the remaining cells showing pyknosis or karyorrhexis were positively stained by the TdT-mediated dUTP nick end labeling (TUNEL) method, and these TUNEL-positive cells showed ultrastructural characteristics of apoptosis. With agarose gel electrophoresis, DNA ladders were clearly detected in bone marrow samples. The number of TUNEL-positive cells in splenic red pulp increased earlier than it did in the splenic white pulp. Thus, T-2 toxin induced-lesions in the hematopoietic tissues and in the lymphoid tissues were brought about by apoptosis of component cells. We believe that damage to the hematopoietic microenvironment may also play an indirect role in the induction of apoptosis in the bone marrow.

Modulation of IL-1beta, IL-6 and TNF-alpha secretion and mRNA expression by the trichothecene vomitoxin in the RAW 264.7 murine macrophage cell line

Oral exposure of mice to vomitoxin (VT) has been previously shown to enhance gene expression of several cytokines associated with macrophage activation. Here, the effects of exposure to VT in vitro on cytokine secretion and mRNA expression were determined in the murine macrophage cell line RAW 264.7. Enzyme-linked immunosorbent assay (ELISA) of supernatants revealed that significant increases in secreted tumour necrosis factor alpha (TNF-alpha) were observed 2 days after exposure to VT at 100 ng/ml and 250 ng/ml, both with and without lipopolysaccharide (LPS) activation. While VT did not affect IL-6 secretion in the absence of LPS, significantly increased IL-6 production was observed in culture supernatants after 1, 2 and 5 days of exposure to VT at 250 ng/ml in the presence of LPS. Soluble IL-1beta was not detected in control or VT-treated cell cultures with or without LPS activation. Immunochemical staining of intracellular cytokines in conjunction with flow cytometric analysis was used to detect the effects of VT on the percentage of positive cells and output per cell. The percentage of cells that produced intracellular TNF-alpha were significantly increased at 100 and 250 ng/ml VT with and without LPS whereas increased IL-6 output per cell was observed at 100 and 250 ng/ml VT with LPS. To assess the effects of VT on cytokine mRNA expression, RAW 264.7 cells were analysed semi-quantitatively using reverse transcription-polymerase chain reaction(RT-PCR) in conjunction with Southern hybridization analysis. Elevated TNF-alpha mRNA was observed at 100 and 250 ng VT/ml at 6 and 24 hr in the absence of LPS. With the addition of LPS, superinduction of TNF-alpha was not observed in the presence of VT. Increased IL-1beta and IL-6 mRNAs were observed at 100 and 250 ng VT/ml at 24 hr in the presence of LPS. These results demonstrated that VT could superinduce both cytokine secretion and mRNA levels in macrophage cultures.

Use of human lymphoblastoid cells to detect the toxic effect of chloramphenicol and metabolites possibly involved in aplastic anemia in man

Some Chloramphenicol (CAP) metabolites are suspected to be involved in the etiology of bone marrow aplasia in man. The objective of the present study was to investigate the cytotoxicity as well as the genotoxicity of CAP and six of its metabolites on human bone marrow cells (RiBM cells) and to compare these results with those obtained on human peripheral blood lymphocytes in order to estimate the relative sensitivity of the two types of cells. Three CAP metabolites NO-CAP, DH-CAP and NPAP inhibited 3H thymidine incorporation in RiBM cells at concentrations ranging from 2.10(-5) M to 2.10(-4) M. NO-CAP appeared as the most potent cytotoxic compound. CAP itself and NAPD presented some toxic effect at high concentration (1-2.10(-3) M). CAPG and HAP did not present any cytotoxic effect. By comparison, the response of human lymphocytes to CAP and its metabolites showed a similar pattern but DH-CAP was the most inhibitory compound. Concerning the genotoxic potential, NO-CAP and DH-CAP induced DNA single strand breaks in RiBM cells at concentrations of 1 and 2.10(-4) M with a dose response relationship. CAP and other metabolites were completely devoid of genotoxicity up to 4.10(-3) M. The results clearly showed that RiBM cells were much less susceptible to the genotoxic effect of CAP metabolites than human lymphocytes.

Alteration of major cytokines produced by mitogen-activated peritoneal macrophages and splenocytes in T-2 toxin-treated male CD-1 mice

Fusarium T-2 toxin has immunotoxic properties that may be related to the modulation of cytokine expression by cells of the immune system. Male CD-1 mice were used to study the effect of in vivo exposure to T-2 toxin on the alteration of interleukin (IL)-1α, tumor necrosis factor α (TNF), and IL-6 in lipopolysaccharide-stimulated peritoneal macrophages, and IL-2, IL-3, and interferon γ (IFNγ) in concanavalin A (Con A)-stimulated splenocytes. Mice were orally dosed with 0, 0.1, 0.5, and 2.5 mg T-2 toxin/kg body weight for 2 weeks on alternate days. Northern blot analysis of IL-1α, TNF, and IL-6 mRNA from activated peritoneal macrophages showed no significant differences between control and treated groups. Measurements of secreted protein by immunoassay demonstrated suppression of these cytokines in all treated groups, suggesting that T-2 toxin affects the translational or post-translational regulation of these cytokines from peritoneal macrophages. Levels of IL-2, IL-3, and IFNγ mRNA from Con A-activated splenocytes were higher in all treated groups. The increases were significant for IL-2 and IFNγ in the groups receiving low (0.1 mg/kg) and high (2.5 mg/kg) doses of T-2 toxin, and for IL-3 in the group receiving a medium (0.5 mg/kg) dose of this toxin (P ≤ 0.05). Results indicated that T-2 toxin given orally at low or medium doses induces transcription or increases mRNA stability of IL-2, IFNγ, and IL-3. Protein levels of all three cytokines were also increased, indicating that T-2 toxin also increases translational/post-translational efficiency of IFNγ, IL-2, and IL-3. Possible mechanisms in the immunosuppressive effects of T-2 toxin may involve endotoxemia resulting after the toxin administration, alteration of the stability of mRNA, or previously described effects of T-2 toxin on protein synthesis.

Comparison of detection methods for trichothecenes produced by Fusarium sporotrichioides on fodder and grains at different air humidities

Growth and toxin production of a highly toxic strain of Fusarium sporotrichioides Sherb were studied on oat and wheat grains and on straw under experimental conditions, in which relative humidity (RH) of air was regulated. The materials were incubated at three different RH levels at a range of 84-100%. F. sporotrichioides grew well on oat and wheat grains at RH 97-100% but grew less well at RH 84-88% and on straw. Toxin production was measured with three biological toxicity tests (cytotoxicity test, dermotoxicity test, and yeast cell toxicity test), with chemical analysis, and T-2 ELISA assay. Cytotoxicity and production of trichothecene mycotoxins were detected in all the samples incubated at all three RH levels. On oat and wheat grains, T-2 toxin, neosolaniol, and diacetoxyscirpenol were found, and on straw T-2 toxin, HT-2 toxin, neosolaniol, and T-2 tetraol were determined. In the T-2 ELISA assay, all material samples were found to contain T-2 toxin. The cytotoxicity test was the most sensitive method for detecting biological toxicity of samples inoculated with fungus. The T-2 ELISA assay and chemical analysis were about equally sensitive to detect T-2 toxin in samples.

Glyceraldehyde-3-phosphate dehydrogenase as a biochemical marker of cytotoxicity by vinyl sulfones in cultured murine spleen lymphocytes

Recently, vinyl sulfones have been observed to selectively inhibit glyceraldehyde-3-phosphate dehydrogenase (GAPDH), which is an important ATP-generating enzyme in glycolysis. The possibility of using GAPDH as a biochemical parameter of cytotoxicity by vinyl sulfones was investigated using mouse lymphocytes. Incubation of lymphocyte GAPDH with ethylvinyl sulfone resulted in a pseudo-first-order loss of enzyme activity. The exposure of lymphocytes to ethylvinyl sulfone resulted in the decrease of GAPDH activity followed by ATP depletion and cell death, which were both dependent on the concentration of ethylvinyl sulfone. A further study on the time-dependent change indicated that cell death was preceded by ATP loss. Compared to ethylvinyl sulfone, divinyl sulfone was more than 8 times more potent in causing either ATP depletion or cell death.

Hematopoietic alterations after exposure to T-2 mycotoxin

Adult mice were exposed by oral gavage to 0.75, 1.25, or 1.75 mg/kg body weight T-2 mycotoxin for 5 consecutive days. Thymic atrophy on the 2nd day following cessation of dosing was profound, and was characterized by significant decreases in the total number of cells within all phenotypes defined by CD4 and CD8 cell-surface antigen expression. Further, the distribution of thymocytes within these phenotypes was significantly altered. Increased percentages of CD4-8- (DN) and decreased percentages of CD4+8+ (DP) cells in thymuses from treated animals suggested that T-2 toxin may inhibit thymocyte maturation. In addition to thymus, the bone marrow of treated animals showed a highly significant hypocellularity, indicating that this hematopoietic compartment may also be targeted by T-2 toxin. A trend toward reduced splenic cellularity was additionally observed in exposed animals, but failed to reach significance. A significant decrease in the total number of both B and T-lymphocytes present within the spleen was observed, however. These data, taken together, indicate that effects at multiple hematopoietic compartments involved in the production of T-lymphocytes may contribute to the peripheral T-cell lymphocytopenia and T-cell mediated immunosuppression produced by T-2 toxin.

Murine lymphocyte proliferation impaired by substituted neosolaniols and calonectrins--Fusarium metabolites associated with trichothecene biosynthesis

The capacity of Fusarium secondary metabolites associated with trichothecene biosynthesis to inhibit murine spleen lymphocyte proliferation was evaluated and compared to that for well known trichothecenes. Activity of these compounds was not specific for B and T lymphocytes since they inhibited [3H]thymidine (TdR) incorporation in unstimulated, Con A- and LPS-stimulated lymphocytes to the same extent. Concentrations of 8-propionyl neosolaniol and 8-butyrylneosolaniol which inhibited [3H]Tdr uptake by 50% (ID50s) were 0.95 and 0.34 ng/ml, respectively. The ID50 for T-2 toxin was 0.26 ng/ml, indicating that there are minor alterations in 12,13-epoxytrichothecene toxicity resulting from the replacement of the isovaleryl moiety on C8 of the trichothecene skeleton with other bulky acyl groups. ID50 values for 4,15-diacetylnivalenol, fusarenon X, deoxynivalenol and 3-acetyldeoxynivalenol were 25, 38, 120 and 1800 ng/ml, respectively. Comparatively, ID50 values for 3,15-dideacetylcalonectrin, 15-deacetylcalonectrin, and 7,8-dihydroxycalonectrin were 390, 2700 and 2400 ng/ml, respectively, indicating that the modified calonectrins had equivalent or less toxicity. Lymphotoxicity of trichothecenes thus decreased upon substitution of acyl groups at the C8 with keto or hydroxy moieties and was also dependent on the nature of substitutions at the C3, C4 and C15 positions. Sambucinol and the trichothecene precursor trichodiene, metabolites which do not contain a 12,13-epoxide, did not inhibit lymphocyte proliferation. The results suggest the need for further assessment of occurrence and in vivo toxicity of Fusarium metabolites, particularly the substituted neosolaniols and calonectrins.

Acute effects of T-2 toxin on radioactive iron incorporation into circulating erythrocytes in mice

The 24-h and 72-h incorporation of 59Fe into circulating erythrocytes in mice were strongly inhibited by a single subcutaneous dose of T-2 toxin given 1 h before the radioisotope. The system is extremely sensitive, since a significant effect was detected with T-2 toxin doses as low as 0.30 mg/kg, which is about one-tenth of the LD50 in the BALB/c strain used for the present study. In the treated animals no initial changes were observed in the blood 59Fe levels or in the rate of radioisotope clearance from plasma, indicating that the toxin does not interfere with iron absorption or transport. It is concluded that the inhibition observed reflects the damage produced by this toxin on reticulocytes and/or erythroblasts, and therefore this method could be of value as a very sensitive means of studying the risk of erythropoietic injury produced by dietary exposure to trichothecene mycotoxins.

In vivo effects of T-2 mycotoxin on synthesis of proteins and DNA in rat tissues

Rats were given an ip injection of T-2 mycotoxin (T-2), the T-2 metabolite, T-2 tetraol (tetraol), or cycloheximide. Serum, liver, heart, kidney, spleen, muscle, and intestine were collected at 3, 6, and 9 hr postinjection after a 2-hr pulse at each time with [14C]leucine and [3H]thymidine. Protein and DNA synthesis levels in rats were determined by dual-label counting of the acid-precipitable fraction of tissue homogenates. Rats given a lethal dose of T-2, tetraol, or cycloheximide died between 14 and 20 hr. Maximum inhibition of protein synthesis at the earliest time period was observed in additional rats given the same lethal dose of the three treatments and continued for the duration of the study (9 hr). With sublethal doses of T-2 or tetraol, the same early decrease in protein synthesis was observed but, in most of the tissues, recovery was seen with time. In the T-2-treated rats. DNA synthesis in the six tissues studied was also suppressed, although to a lesser degree. With sublethal doses, complete recovery of DNA synthesis took place in four of the six tissues by 9 hr after toxin exposure. The appearance of newly translated serum proteins did not occur in the animals treated with T-2 mycotoxin or cycloheximide, as evidenced by total and PCA-soluble serum levels of labeled leucine. An increase in tissue-pool levels of free leucine and thymidine in response to T-2 mycotoxin was also noted. T-2 mycotoxin, its metabolite, T-2 tetraol, and cycloheximide cause a rapid inhibition of protein and DNA synthesis in all tissue types studied. These results are compared with the responses seen in in vitro studies.

Immunosuppressive effects of four trichothecene mycotoxins

The trichothecenes are a family of mycotoxins contaminating some food and feeds. We have studied the inhibitory effect of four of them including less toxic compounds: T-2 toxin, DAS, DON and Trichodermin, on normal human peripheral blood lymphocytes and murine splenic lymphocytes. The results show that even for the least toxic compound, inhibiting concentrations can be realised in the blood by common alimentary contamination.

Effect of in vivo administration of T-2 toxin on peritoneal murine macrophages

We investigated the effect of in vivo administration of T-2 toxin, a 12,13-epoxytrichothecene produced by several Fusarium species, on murine macrophage metabolism. Cytoplasmic and lysosomal enzyme levels, generation and release of superoxide anion, phagocytosis and intracellular killing of Salmonella typhi and murine P815 tumour cell lysis were measured under different experimental conditions. When T-2 toxin was administered to mice at sublethal doses (0.50-1.00 mg/kg/24 hr), the levels of lysosomal and cytoplasmic enzyme activity and the generation of superoxide anion were significantly enhanced as compared to controls. This correlated with increased phagocytosis and intracellular killing of S. typhi. Cytotoxic activity against murine P815 mastocytoma cells exhibited by macrophages isolated from mice treated with T-2 toxin was inhibited in a dose-dependent manner. In vivo administration of T-2 toxin may result in the activation of specific metabolic pathways of peritoneal macrophages, while inhibiting other paths.