Question

Which one of the following immunoglobulin is responsible for atopic allergy?

• A. IgG
• B. IgM
• C. IgE
• D. IgA

Hint:

Remember the mnemonic "Ig\textbf{E} for \textbf{E}mergency" or "Allerg\textbf{E}". This helps associate the IgE isotype with immediate hypersensitivity and allergic reactions.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Atopic allergy, also known as type I hypersensitivity, is an allergic reaction mediated by a specific class of antibodies (immunoglobulins). The question asks to identify this specific class.

Step 2: Detailed Explanation:
- IgE: This immunoglobulin is primarily responsible for allergic reactions. In an allergic individual, the immune system produces IgE antibodies in response to an allergen (e.g., pollen). These IgE antibodies then bind to the surface of mast cells and basophils. Upon subsequent exposure to the same allergen, the allergen cross-links the IgE on these cells, causing them to degranulate and release inflammatory mediators like histamine, leading to allergic symptoms.
- IgG: This is the most abundant immunoglobulin in the blood and is crucial for combating bacterial and viral infections.
- IgM: This is the first antibody produced during an initial immune response. It exists as a pentamer and is very effective at activating the complement system.
- IgA: This is the main immunoglobulin found in mucosal secretions like saliva, tears, and breast milk, providing the first line of defense at mucosal surfaces.

Step 3: Final Answer:
The immunoglobulin responsible for atopic allergy is IgE. Therefore, option (C) is correct.