ALLERGY

Allergy

An allergy is a hypersensitivity disorder of the immune system. Allergic reactions occur when a person's immune system reacts to normally harmless substances in the environment. A substance that causes a reaction is called an allergen. These reactions are acquired, predictable, and rapid. Allergy is one of four forms of hypersensitivity and is formally called type I hypersensitivity. Allergic reactions are distinctive because of excessive activation of certain white blood cells called mast cells and basophils by a type of antibody called Immunoglobulin E . This reaction results in an inflammatory response which can range from uncomfortable to dangerous.

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allergy

Noun

  1. A disorder of the immune system causing adverse reactions to substances (allergens) not harmful to most and marked by the body's production of histamines and associated with atopy, anaphylaxis, and asthma.
  2. Any condition of hypersensitivity to a substance.
  3. Altered susceptibility to a first treatment as exhibited in reaction to a subsequent one.
  4. An antipathy, as toward a person or activity.
    He has an allergy to reality TV.


The above text is a snippet from Wiktionary: allergy
and as such is available under the Creative Commons Attribution/Share-Alike License.

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