Lewis triple response is caused due to
**Core Concept**
The Lewis triple response is a physiological response observed in the skin, characterized by a triad of flushing, wheal, and flare reactions. This response is mediated by the release of histamine from mast cells, leading to vasodilation and increased blood flow.
**Why the Correct Answer is Right**
The Lewis triple response is caused by the release of histamine from mast cells, which are activated by the presence of allergens or irritants. Histamine binds to H1 receptors on the surface of endothelial cells, leading to the relaxation of smooth muscle and increased vascular permeability. This causes the characteristic wheal and flare reactions, as well as the flushing of the skin.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the Lewis triple response is not caused by the release of acetylcholine, which is involved in the parasympathetic nervous system.
**Option B:** This option is incorrect because the Lewis triple response is not caused by the release of bradykinin, which is involved in the inflammatory response.
**Option C:** This option is incorrect because the Lewis triple response is not caused by the release of serotonin, which is involved in the regulation of mood and appetite.
**Clinical Pearl / High-Yield Fact**
The Lewis triple response is a classic example of a histamine-mediated response, and is often used as a diagnostic tool to identify allergic reactions.
**Correct Answer:** D. Histamine