Mucosal immunology of tolerance and allergy in the gastrointestinal tract.

The mucosal immune system typically exists in a state of active tolerance to food antigens and commensal bacteria. Tolerance to food proteins is induced in part by dendritic cells residing in the intestinal mucosa and implemented by regulatory T cells. Food allergy occurs when immune tolerance is disrupted and a sensitizing immune response characterized by food-specific IgE production occurs instead. Experimental food allergy in mice requires use of adjuvant or exploitation of alternate routes of sensitization to induce allergic sensitization, and can aid in understanding the mechanisms of sensitization to food allergens and the pathophysiology of gastrointestinal manifestations of food allergy. Recent work in the understanding of mucosal immunology of tolerance and allergy in the gastrointestinal tract will be discussed.