Wheal-flare reaction

Definition

A wheal-flare reaction is a localized skin response characterized by a raised, red, itchy bump (wheal) surrounded by a reddish area (flare). It typically occurs as a result of an allergic reaction mediated by histamine release from mast cells.

5 Must Know Facts For Your Next Test

1. Wheal-flare reactions are common in Type I hypersensitivity reactions, such as those caused by insect stings or allergen exposure.
2. Histamine release from mast cells is the primary mediator of the wheal and flare response in the skin.
3. The wheal represents localized edema and the flare represents vasodilation and increased blood flow.
4. Wheal-flare reactions can be used diagnostically in allergy testing to identify specific allergens that trigger a patient's immune response.
5. Antihistamines are commonly used to treat wheal-flare reactions by blocking histamine receptors.

Review Questions

Related terms

Type I Hypersensitivity: An allergic reaction mediated by IgE antibodies and mast cell degranulation.

Histamine:

A compound released by mast cells during allergic reactions causing vasodilation and increased vascular permeability.

Allergy Testing: Diagnostic procedures used to identify specific allergens that cause hypersensitive immune responses in individuals.