In recent years considerable progress has been achieved in regard to our understanding of the induction and modulation of the immune response in the intestinal mucosa. It is clear that this mucosal immune reaction is predominantly steered by certain T-cell populations, which are characterized by their cytokine secretion profile. Less well known are the conditions under which the uptake and processing of a specific antigen leads to a certain immune response, whether it be protective, tolerant or inflammatory. However, here again distinct progress has been made in our understanding. Equally...