Allergen
type of antigen that produces an abnormally vigorous immune response
An allergen is an otherwise harmless substance that triggers an allergic reaction in sensitive individuals by stimulating an immune response.
In technical terms, an allergen is an antigen that is capable of stimulating a type-I hypersensitivity reaction in atopic individuals through immunoglobulin E (IgE) responses. Most humans mount significant immunoglobulin E responses only as a defense against parasitic infections. However, some individuals may respond to many common environmental antigens. In atopic individuals, non-parasitic antigens stimulate inappropriate IgE production, leading to type I hypersensitivity.
Sensitivities vary widely from one person (or from one animal) to another. A very broad range of substances can be allergens to sensitive individuals.
The World Health Organization and International Union of Immunological Societies (WHO/IUIS) Allergen Nomenclature Sub-Committee maintains a webpage listing every protein (as well as some carbohydrates) that have elicited a confirmed IgE reaction in humans.
Examples
Allergens can be found in a variety of sources, such as dust mite excretion, Food allergies are not as common as food sensitivity, but some foods such as peanuts (a legume), nuts, seafood and shellfish are the cause of serious allergies in many people.
The United States Food and Drug Administration recognizes nine foods as major food allergens: organic fats as well as sulfites (chemical-based, often found in flavors and colors in foods) at 10ppm and over.
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Vocabulary and entity names are the principal evidence signals here, because they determine the precision of every later search. The source revision retrieved here is dated Sep 21, 2026. The linked authority identifier is Q186752. The Library of Congress control number is sh85003659. 1 of 1 selected statements include explicit references; 1 carry qualifiers and 0 use preferred rank.
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This entry incorporates text from “Allergen” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.