Question

Most abundant immunoglobulin of normal animal

• A. IgG
• B. IgD
• C. IgA
• D. IgM

Hint:

To easily recall immunoglobulin abundances, use the acronym GAMED:
\[ \text{IgG} > \text{IgA} > \text{IgM} > \text{IgE} > \text{IgD} \]

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Immunoglobulins (antibodies) are glycoproteins synthesized by plasma cells in response to foreign immunogenic challenges.

Step 3: Detailed Explanation:
There are five main classes of immunoglobulins in mammals: IgG, IgM, IgA, IgE, and IgD.
- IgG: This is the most abundant immunoglobulin in the serum and extravascular fluids of normal animals, accounting for approximately \(75\%\) to \(80\%\) of the total serum antibody pool. It plays a major role in secondary immune responses, neutralization, and opsonization.
- IgM: A pentameric antibody that is the first class produced during a primary immune response, representing around \(10\%\) of serum antibodies.
- IgA: The dominant antibody class in external secretions (milk, saliva, tears, and mucous membranes), but present in lower amounts in serum.
- IgD/IgE: Present in very low concentrations in normal serum.

Step 4: Final Answer
The most abundant immunoglobulin class in healthy animals is IgG.