The in vitro effects of trichothecenes on the immune system.

Since Fusarium-derived trichothecenes have shown immunosuppressive properties in laboratory animals, the possibility that deoxynivalenol (DON) and acetyldeoxynivalenol (AcDON) might affect the in vitro production of interleukins by macrophages or lymphocytes was studied. When the effects of low and high concentrations of DON on lymphocyte proliferation were compared, phytohaemagglutinin-induced proliferation was enhanced at concentrations between 0.005 and 0.5 ng DON/ml whereas 50 or 100 ng/ml caused a decrease in proliferation. In experiments in which lymphocytes were exposed briefly to 90 ng DON/ml, the level of thymidine incorporation was increased to 130% of control levels. Both DON and AcDON were shown to induce interleukin 1 (IL-1) release in peritoneal macrophages by a mode of action similar to that of cycloheximide. In the presence of DON, cellular IL-1 did not decay, and this resulted in a marked release of IL-1 from the cell during the period of exposure to the inhibitor. This suggests that in vivo effects of trichothecenes on the immune system may vary according to the level of exposure.