Definition: A foreign substance which causes the immune system to produce immunoglobulin E antibody (IgE) against the substance. The IgE binds to cells such as mast cells and basophils. Upon re-exposure, the same foreign substance binds to IgE, causing chemical mediators to be released from the mast cells and basophils, resulting in vasodilation, itching, sneezing, wheezing and other allergic symptoms.
Allergy
By Daniel More, MD, About.com Guide
About.com Health's Disease and Condition content is reviewed by our Medical Review Board
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