Applied physiology: understanding allergy

Abstract 

Atopic individuals generate specific IgE antibodies to allergens. When exposed to an allergen, cross-linkage of IgE antibodies bound to mast cells and basophils results in degranulation of the cell with release of preformed mediators and activation of enzymes involved in arachidonic acid synthesis. The patient experiences itching, ery-thema, swelling of the skin and mucous membranes and bronchospasm. The early response to an allergen starts within minutes and has usually resolved within an hour. If the tissue is already inflamed, or the dose of the allergen is large, the early response is followed by a late phase response, maximal at 6–12 h. This involves T cell activation, upregulation of adhesion molecules and eosinophil activation and secretion. Severe allergic reactions can be fatal and the pathophysiology of anaphylactic shock is discussed.

Keywords: allergens, anaphylaxis, hypersensitivity delayed, hypersensitivity immediate, IgE

No full text is available. To read the body of this article, please view the PDF online.

• f1 Correspondence to: SL. Tel.: +44-20-7737-4000x4647; Fax: +44-20-7346-3643; E-mail: susan.leech@kcl.ac.uk