Effects of vomitoxin (deoxynivalenol) and cycloheximide on IL-2, 4, 5 and 6 secretion and mRNA levels in murine CD4+ cells

Abstract

The effects of continuous in vitro exposure to the trichothecene, vomitoxin (VT) or another protein synthesis inhibitor, cycloheximide (CHX), on interleukin (IL) secretion and mRNA levels were evaluated in murine splenic CD4+ cells. Significant increases were seen in supernatant IL-2, IL-4 and IL-5 obtained from 7 day Concanavalin A (Con A)-stimulated CD4+ cultures containing VT concentrations of 250, 100 and 100 ng/ml, respectively, compared with controls run in the absence of VT. The effect of VT on CD4+ cell proliferation was also assessed after culturing for 3, 5 and 7 days with Con A. Although total cell numbers were not affected at day 3, cultures at day 5 with 50 or more ng VT/ml and at day 7 with 100 or more ng VT/ml had significantly lower cell numbers than controls. In addition, viable cell number was unaffected at day 3, but was significantly decreased at day 5 by VT concentrations of 12.5 ng or more ml and at day 7 by 100 or more ng VT/ml. Elevations in IL-2, IL-4 and IL-5 were also observed in 7-day Con A-stimulated CD4+ cell cultures containing CHX at 50-100, 50 and 10 ng/ml, respectively. When CD4+ cells were stimulated with Con A in the absence of inhibitors and then subjected to reverse transcriptase-polymerase chain reaction coupled with Southern analysis, maximal IL-2, IL-4 and IL-6 mRNA levels were induced at 48 hr whereas peak IL-5 mRNA was observed at 72 hr. Superinduction of IL-2 mRNAs was observed in the presence of VT at 50-100 ng/ml and CHX at 50-250 ng/ml. IL-4 and IL-5 mRNAs were superinduced by VT at 100 ng/ml and CHX at 50 ng/ml. The results suggest that VT and CHX could superinduce both interleukin secretion and mRNA transcript levels in CD4+ cell cultures and that, for VT, these effects occurred concurrently with inhibition of cell proliferation.