From the Research
The Triple Response of Lewis, also known as the Lewis triple response, refers to a three-part skin reaction consisting of wheal formation, flare, and pruritus, which occurs due to the release of histamine and other inflammatory mediators from mast cells when an allergen binds to IgE antibodies on their surface. This reaction is clinically important for diagnosing allergies and understanding the pathophysiology of type I hypersensitivity reactions. The intensity of the reaction can help determine the severity of an allergy, with stronger reactions indicating greater sensitivity to the allergen.
The triple response is characterized by:
- Wheal formation (localized swelling)
- Flare (surrounding redness)
- Pruritus (itching)
This phenomenon was first described by Sir Thomas Lewis in the early 20th century and remains fundamental to modern allergy testing and immunology 1. The reaction occurs due to the release of histamine, which acts via H1 and H2 receptors to produce vasodilation and increased vascular permeability, leading to the characteristic wheal and flare response 1.
In terms of treatment, antihistamines such as levocetirizine and desloratadine have been shown to inhibit the allergen-induced wheal and flare response, with levocetirizine being more potent than desloratadine 2. Additionally, up-dosing antihistamines up to fourfold or higher has been found to be effective and safe in treating chronic spontaneous urticaria, with limited side effects 3.
Overall, the Triple Response of Lewis is a crucial concept in understanding allergic reactions and diagnosing allergies, and its treatment involves the use of antihistamines to alleviate symptoms.