ABSTRACT
A food allergy is any adverse reaction to a food that is mediated by the immune system. The most well-known type of food allergy reactions are those that involve IgE antibody specifically directed to peptide epitopes, either conformational or sequential in nature, on proteins within an edible food. IgE antibodies bind to high affinity receptors on effector cells called mast cells (distributed in tissues, and especially rich in skin and mucosa) and basophils (found circulating in blood, but can egress into tissues). When two or more IgE antibodies are cross-linked, the mast cell or basophil is activated, resulting in release of preformed and newly formed chemical and peptide mediators, which may continue to amplify an allergic reaction (Figure 8.1 and Table 8.1). Histamine is the most well-known of these mediators, but cystinyl leukotrienes, cytokines, and chemokines that attract additional inflammatory cells to the site of a reaction are critically important as well, most easily seen on a practical level by the fact that while histamine receptor blockers (antihistamines) may block urticarial (hive) reactions, they do not stop anaphylaxis, which involves multiple mediators at multiple organ sites.
