Oral tolerance induction in humans

Oral tolerance designates the status of systemic hyporesponsiveness against an antigen that makes contact with the immune system via the mucosa of the gastrointestinal tract. In various animal models of autoimmune disease the feeding of the particular autoantigen has been shown to tolerize the animal, thereby ameliorating the course of disease. In contrast, effectivity has not been found in human trials to induce oral tolerance in patients suffering from autoimmune disease. However, the underlying mechanisms of tolerance in rodents, in particular the induction of anti-inflammatory cytokines, seem to be functional in humans as well. Studies using the human neoantigen keyhole limpet hemocyanin (KLH) offer experimental access to examine cellular and molecular basics of oral tolerance in humans required to raise the efficiency of oral tolerance induction in clinical trials.

► Oral tolerance induction has been effective in animal models of autoimmune disease.
► Human clinical trials of oral tolerance have not established effectivity so far.
► Mechanisms of tolerance, however, seem to be functional in humans as well.
► Experimental studies of oral tolerance have shown promising but diverse results.
► Basic studies are required to explore the therapeutic potential of oral tolerance.