ELEVATED GENE-EXPRESSION AND PRODUCTION OF INTERLEUKIN-2, INTERLEUKIN-4, INTERLEUKIN-5, AND INTERLEUKIN-6 DURING EXPOSURE TO VOMITOXIN (DEOXYNIVALENOL) AND CYCLOHEXIMIDE IN THE EL-4 THYMOMA

Aberrant elevation of serum IgA and induction of murine IgA nephropath y following dietary exposure to the naturally occurring trichothecene vomitoxin (VT or deoxynivalenol) may involve dysregulation of cytokine production at the T cell level. EL4.IL-2 (EL-4), a cloned thymoma tha t produces interleukins (IL)-2, 4, 5, and 6, was used as a T cell mode l to investigate the in vitro effects of VT on interleukin production and gene expression. When supernatants of cells stimulated with phorbo l 12-myristate 13-acetate (PMA) were assessed by enzyme-linked immunos orbent assay, IL-2, 4, and 5 were increased in the presence of 50 and/ or 100 ng/ml VT for 2 and/or 8 days of culture. IL-2, 5, and 6 were al so significantly elevated in the presence of 10-100 ng/ml of cyclohexi mide (CHX), another protein synthesis inhibitor, after 8 days of cultu re. As demonstrated by Northern analysis, VT at the levels between 50 and 100 ng/ml superinduced IL-2, 4, 5, and 6 mRNAs in PMA-stimulated E L-4 cells during a 24 hr culture period. Similar effects in PMA-treate d samples were observed for CHX at 50, 100, 250, 1000, and 10000 ng/ml . mRNA levels for both IL-4 and IL-5, but not IL-2 and IL-6, were incr eased in unstimulated EL-4 cultures exposed to 50 and 100 ng/ml VT for 48 hr when analyzed by reverse transcriptase-polymerase chain reactio n. Using [H-3]leucine incorporation as a measurement of protein synthe sis, IC(50)s for VT and CHX were estimated to be 280 and 55 ng/ml, res pectively. This study indicates that VT as well as CHX could increase production of several interleukins in the EL-4 model even when present at concentrations that partially inhibited protein synthesis, whereas IL mRNA superinduction occurred across a broader range of concentrati ons that included maximal protein synthesis inhibition. (C) 1994 Acade mic Press, Inc.