Foods enter the gastrointestinal tract and undergo protein digestion and then antigen (Ag) processing. Some Ag enters the blood stream to be distributed at distal sites throughout the body (particularly the skin and respiratory mucosa along with sites in the gastrointestinal mucosa). As the antigen-presenting cell presents Ag to the T cell, specific cytokines are produced. In the peanut-allergic individual, the T cells will secrete increased amounts of IL-4, IL-5, and IL-13, among other mediators, and reduced amounts of IFN-γ and TNF-α when compared to that in an individual who is not allergic to peanuts. The T cell in turn regulates eventual peanut-specific IgE production by B cells. Peanut-specific IgE is attached to mast cells in the gastrointestinal tract, skin, and respiratory tract mucosa. Subsequently, on ingestion of peanuts, in the peanut-allergic individual, the protein is digested and the Ag binds peanut-specific IgE on the mast cell, causing activation of the mast cell with mediator release at the mucosal site. Clinical symptoms ensue.