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inflammatory mediators can cause itching, contraction of smooth muscle, vasodilation, and secretion of mucus. Manifestations, which are most often systemic, may involve the skin, gastrointestinal tract, or respiratory system (see Figure 29-1).The gastrointestinal tract is the most frequent means of food allergy development. A lack of oral toleranceis the current focus in food allergy development. The gastrointestinal tract determines how to consider each food protein with every exposure. The potential to develop food allergies is great, yet comparatively few people do. Basically the body inhibits immune responses by prior exposure via the Tregulatory cells. Food allergy is believed to occur when oral tolerance fails (Chehade and Mayer, 2005;Akdis et al., 2005).Researchers are now focusing on what goes on with oral tolerance and how this relates to food allergen families.In recent years common plant food allergens have been identified with a limited number of protein families. There appears to be significant cross-reactivity of most food allergens with specific proteins causing the majority of allergic reactions. The families are characterized by biochemical and physicochemical properties. Surprisingly, food allergens of animal origin share many