Allergy

An allergy or Type I hypersensitivity is an immune malfunction whereby a person's body is hypersensitised to react immunologically to typically nonimmunogenic substances. When a person is hypersensitised, these substances are known as allergens. The word allergy derives from the Greek words allos meaning "other" and ergon meaning "reaction" or "reactivity". Type I hypersensitivity is characterised by excessive activation of mast cells by immunoglobulin E resulting in a systemic inflammatory response that can result in symptoms as benign as a runny nose, to life-threatening anaphylactic shock and death.

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Allergen: An allergen is any substance (antigen), most often eaten or inhaled, that is recognized by the immune system and causes an allergic reaction....

Greek: The noun Greek refers to:...

Mast cell: A mast cell (or mastocyte) is a resident cell of connective tissue that contains many granules rich in histamine and heparin. Although best known for their role in allergy and anaphylaxis, mast cells play an important protective role as well, being intimately involved in wound healing and defense ag...