Question

Match LIST-I with LIST-II

LIST-I (Immunoglobulin Class)		LIST-II (Characteristics)
A. IgG	I. Serves as part of B-cell receptor complex
B. IgA	II. Anaphylactic mediating antibody
C. IgD	III. Most abundant in body fluid, neutralize toxins, opsonizes bacteria
D. IgE	IV. Secretory antibody and protect mucous membrane

Choose the correct answer from the options given below:

• A. A-I, B-II, C - III, D - IV
• B. A-I, B - III, C - II, D - IV
• C. A-I, BII, C - IV, D - III
• D. A-III, B - IV, C - I, D - II

Hint:

Use the mnemonic "GAME-D" to remember the isotypes. \textbf{G} is the most abundant and goes everywhere. \textbf{A} is in secretions ("secretory"). \textbf{M} is the first responder (not in this list). \textbf{E} is for allergy ("Eeeek! a bee!"). \textbf{D} is a receptor on B-cells.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
This question requires matching the five major classes (isotypes) of immunoglobulins (antibodies) with their primary functions or characteristics.
Step 2: Detailed Explanation:
Let's match each immunoglobulin class with its correct characteristic:


A. IgG: This is the most abundant immunoglobulin in serum and body fluids. It is a workhorse of the humoral immune response, capable of neutralizing toxins, opsonizing pathogens for phagocytosis, and activating the complement system. This matches III. Most abundant in body fluid, neutralize toxins, opsonizes bacteria.

B. IgA: This is the main antibody found in secretions such as mucus, saliva, tears, and breast milk. It exists as a dimer in secretions and plays a crucial role in protecting mucosal surfaces from pathogens. This matches IV. Secretary antibody and protect mucous membrane. (Note: "Secretary" is a typo for "Secretory").

C. IgD: This immunoglobulin is found in very low concentrations in the serum. Its primary role is to act as an antigen receptor on the surface of mature, naive B-lymphocytes, as part of the B-cell receptor (BCR) complex along with IgM. This matches I. Serves as part of B-cell receptor complex.

D. IgE: Even though it is present in the lowest concentration in serum, IgE is famous for its role in allergic reactions (Type I hypersensitivity). It binds to receptors on mast cells and basophils, and upon cross-linking by an allergen, triggers the release of inflammatory mediators like histamine, leading to anaphylaxis. This matches II. Anaphylactic mediating antibody.

Step 3: Final Answer:
The correct matching is A-III, B-IV, C-I, D-II. This corresponds to option (D).