Oral tolerance is determined at the level of draining lymph nodes.

In the skin and in the epithelium of the oral mucosa a comparable network of Langerhans cells can be found. Antigen application on either epithelium leads to rapid emigration of Langerhans cells to the draining lymph nodes. Application on the oral mucosa leads to tolerance induction while application on the skin results in sensitization of the animal. Here we show that there are no differences in the antigen presentation capacity of oral mucosa- and skin-derived dendritic cells. However, measurement of IFN-gamma and IL-5 production, as representatives of Th1 and Th2 cytokines respectively, in total lymph node suspensions after sensitization via the skin or oral mucosa demonstrated a skewing of the response towards Th2 after antigen application on the oral mucosa. Together with our previous studies, in which it was shown that oral tolerance induction is not inherent to oral mucosa-derived dendritic cells, we postulate that oral tolerance is determined at the level of draining lymph nodes influenced by local cytokine profiles.