Which part of the IgE antibody is responsible for binding to mast cells and basophils?
**Core Concept**
The IgE antibody plays a crucial role in triggering allergic reactions through its interaction with mast cells and basophils. This interaction is essential for the release of histamine and other mediators that contribute to allergic symptoms.
**Why the Correct Answer is Right**
The Fcε region of the IgE antibody is responsible for binding to the high-affinity IgE receptor (FcεRI) on the surface of mast cells and basophils. This binding is a critical step in the initiation of allergic responses, as it allows the IgE antibodies to deliver antigens to these cells, leading to their activation and the subsequent release of histamine and other chemical mediators.
**Why Each Wrong Option is Incorrect**
**Option A:** The Fab region of the IgE antibody is responsible for binding to antigens, not mast cells and basophils.
**Option B:** The Fc region of the IgE antibody is involved in binding to the low-affinity IgE receptor (FcεRII), but not the high-affinity receptor responsible for triggering allergic responses.
**Option C:** The constant region of the IgG antibody is not relevant to the binding of IgE to mast cells and basophils.
**Clinical Pearl / High-Yield Fact**
The IgE antibody is a key player in allergic diseases, and its interaction with mast cells and basophils is essential for the development of allergic symptoms. Understanding the role of the Fcε region in this interaction is crucial for the diagnosis and treatment of allergic disorders.
**Correct Answer:** C. Fcε region