Henoch–Schonlein purpura is characterized by the deposition of the following immunoglobulin around the vessels –
**Core Concept**
Henoch-Schonlein purpura (HSP) is a form of vasculitis that affects small blood vessels, characterized by the deposition of immune complexes around the vessels. This condition is associated with the activation of the immune system and the release of various inflammatory mediators.
**Why the Correct Answer is Right**
The correct answer is IgA. In HSP, IgA immune complexes are deposited around the vessels, leading to inflammation and damage. This deposition is thought to be due to the abnormal production of IgA antibodies, which then bind to the endothelial cells of the blood vessels, triggering an inflammatory response. The IgA immune complexes activate the complement system, leading to the release of various inflammatory mediators, such as histamine and bradykinin, which cause the characteristic purpura and other symptoms of HSP.
**Why Each Wrong Option is Incorrect**
* **Option A:** IgG - While IgG is an important antibody that plays a role in various immune responses, it is not the primary immunoglobulin associated with HSP.
* **Option B:** IgM - IgM is another type of antibody that is involved in the early stages of immune responses, but it is not the primary immunoglobulin associated with HSP.
* **Option D:** IgE - IgE is primarily involved in allergic reactions and is not associated with HSP.
**Clinical Pearl / High-Yield Fact**
HSP is often associated with other systemic symptoms, such as abdominal pain, arthritis, and renal involvement, and can be a manifestation of systemic vasculitis.
**Correct Answer:** C.