Secondary metabolites of Aspergillus exert immunobiological effects on human monocytes

This project focused on the effects of aflatoxin B1 (AFB1), a food-contamin ating mycotoxin produced by fungi, genus Aspergillus, on the release and ge netic expression of some important cytokines, i.e., (interleukin-1 alpha (I L-1 alpha), IL-6, tumor necrosis factor-alpha (TNF alpha)) by human monocyt es. Monocytes, preincubated for different time periods with concentrations of AFB1 ranging from 0.01 to 1.0 pg/mL, were then activated with bacterial Lipopolysaccharide. Cytokine levels were measured by immunoassay and mRNA b y cDNA amplification. Pretreatment of monocytes with AFB1 resulted in a dec rease in IL-1, IL-6 and TNF alpha release already at a concentration of 0.0 5 pg/mL. The gene expression of the cytokines considered was drastically af fected by treatment with AFB1. In fact, AFB1 completely blocked the transcr iption of IL-1 alpha, IL-6 and TNF alpha mRNAs, while it did not affect bet a-actin mRNA at the concentrations used. It therefore appears that AFB1 exe rts its effect on cytokine release through selective inhibition of specific mRNA, without affecting general protein synthesis. (C) Elsevier, Paris.