Question

Which one of the following antibody types protects against inhaled and ingested pathogens?

• A. IgG
• B. IgD
• C. IgM
• D. IgA

Hint:

IgA is the primary antibody found in mucosal areas (such as the lungs and intestines) where it provides protection against pathogens that enter through inhalation or ingestion.

Answer 1

The Correct Option is D

Step 1: Understanding the antibody types.
Immunoglobulins (Ig) are antibodies that play critical roles in the immune system by identifying and neutralizing foreign objects like bacteria, viruses, and toxins. Each class of immunoglobulin has a specific function:

• IgG: The most abundant antibody in blood and extracellular fluid, primarily involved in systemic immune responses and protection against bacterial and viral infections.
• IgD: Found on the surface of immature B cells, it plays a role in initiating immune responses but is not primarily responsible for protecting against pathogens in the respiratory or digestive systems.
• IgM: The first antibody produced during the initial immune response. It is mainly found in the blood and is efficient at activating the complement system.
• IgA: This antibody is found in mucosal areas such as the respiratory and gastrointestinal tracts. It provides protection against inhaled and ingested pathogens by neutralizing them before they can invade the body’s cells.

Step 2: Conclusion.
IgA is the antibody type that provides immunity in mucosal surfaces such as the respiratory and gastrointestinal tracts, where it protects against inhaled and ingested pathogens. Therefore, the correct answer is IgA.