wheal-and-flare reaction

wheal-and-flare reaction

n.

The characteristic immediate reaction to an injected allergen in a skin test, in which an irregular blanched wheal appears, surrounded by an area of redness. Also called wheal-and-erythema reaction.

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wheal-and-flare reaction

Etymology: AS, walu + flare + ME, fleare, to blaze up; L, re, again, agere, to act

a skin eruption that may follow injury or injection of an antigen. It is characterized by swelling and redness caused by a release of histamine. The reaction usually occurs in three stages, beginning with the appearance of an erythematous area at the site of injury, followed by development of a flare surrounding the site; finally a wheal forms at the site as fluid leaks under the skin from surrounding capillaries.

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wheal-and-flare reaction (wēlˑ -and-flerˈ rē·akˑ·shn),

n a three-stage reaction that develops on the surface of the skin because of injury or exposure of the body to an antigen via injection. The condition is characterized by redness and swelling that results from release of histamine.

Wheal-and-flare reaction.

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wheal-and-flare reaction

Triple response of Lewis Immunology A series of 3 sequential responses that occur in skin subjected to minor trauma, caused by tissue release of histamine; WFR tests immediate hypersensitivity–'reaginic' or allergic reaction to an antigen, and can be transferred to a nonallergic person. See P-K test.