Which of the following antibodies are mediator of an allergic response?

Options

A. `I_gA`
B. `I_gD`
C. `I_gM`
D. `I_gE`

Answer

To determine which antibodies mediate an allergic response, let's analyze the options provided:

1. **Understanding Antibodies**: Antibodies, also known as immunoglobulins (Ig), are proteins produced by the immune system to identify and neutralize pathogens like bacteria and viruses. There are five main types of antibodies in the human body: IgG, IgA, IgD, IgM, and IgE.

2. **Analyzing Each Option**:
- **IgA**: This antibody is primarily found in mucosal areas, such as tears, saliva, and breast milk. It plays a crucial role in mucosal immunity but is not directly involved in allergic responses.
- **IgD**: This antibody is mainly found on the surface of B cells and is involved in the initiation of B cell activation. It does not play a significant role in allergic reactions.
- **IgM**: This is the largest antibody and is the first to be produced in response to an infection. While it is important for the initial immune response, it is not specifically associated with allergies.
- **IgE**: This antibody is specifically involved in allergic reactions and hypersensitivity responses. It binds to allergens and triggers the release of histamines and other chemicals from mast cells and basophils, leading to the symptoms of allergies.

3. **Conclusion**: Based on the analysis, the antibody that mediates allergic responses is **IgE**.

Thus, the correct answer is **IgE (Option 4)**.