Intraepithelial processes of dendritic cells in pigs exposed to the mycotoxin deoxynivalenol

The mycotoxin deoxynivalenol (DON) is contaminating crops and has effects on the intestinal immune system. DON-exposure inhibits maturation and function of dendritic cells (DC), thus affecting the initiation or suppression of a mucosal immune response (Bimczok et al., Immunobiology, vol. 212 pp 655-666, 2007). There is evidence that DC extend processes into the gut epithelium to sample luminal antigens. We conducted an in vivo study with pigs (~40kg BW) fed a DON-containing diet (4 mg DON/kg feed) and infunded with either NaCl or LPS (7.5 µg/kg BW) at the end of the experiments. Paraffin-embedded sections of jejunum were analysed microscopically with MHC II and laminin antibodies to estimate DON effects on intraepithelial DC-processes. Signals of intraepithelial MHC II immunoreactivity indicating DC-processes per 1000 µm basement membrane were counted in the epithelium. In DON-fed pigs the immunoreactivity was markedly reduced in comparison to control animals. After systemic intravenous LPS challenge the signal frequency was higher in control-fed pigs than in DON-fed. Further work is under progress to characterise the intraepithelial MHC II positive processes with respect to the interaction between DC and epithelial cells.