MedlinePlus Medical Encyclopedia: Recognizing invader

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Recognizing invader

An allergy occurs when the immune system reacts to substances (allergens) that are generally harmless and in most people do not cause an immune response. Antibodies are formed by the immune system in response to the presence of an antigen such as pollen, mold, dust or dander.

Update Date: 10/30/2006

Updated by: Donald Accetta, MD, MPH, President, Allergy & Asthma Care, PC, Taunton, MA. Review provided by VeriMed Healthcare Network.

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