Question

Immunoglobulin's function is

• A. Vasodilation
• B. Chemotaxis
• C. Activation of complement system
• D. Inflammation

Hint:

Antibodies act as target markers.
Once they bind to an antigen, they activate the complement cascade to destroy the target cell.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Immunoglobulins (antibodies) are specialized glycoproteins produced by B-lymphocytes that bind specifically to foreign antigens to neutralize them or target them for destruction by other immune mechanisms.

Step 2: Detailed Explanation:
Let us analyze the physiological functions of the options:
Vasodilation, Chemotaxis, and Inflammation are generalized physiological responses mediated by chemical messengers like histamines, cytokines, and prostaglandins during tissue damage or infection.
Immunoglobulins are highly specific adaptive immune molecules.
While they do not directly cause vasodilation or chemotaxis on their own, their binding to an antigen initiates several major effector pathways.
One of the most important classical functions of specific immunoglobulins (especially IgM and certain IgG subclasses) is the activation of the complement system.
When an antibody binds to its target antigen on a pathogen's cell surface, it undergoes a conformational change that exposes a binding site for the C1q protein of the complement system.
This triggers the classical complement cascade, leading to the formation of the Membrane Attack Complex (MAC) that lyses the pathogen, and the release of opsonins that enhance phagocytosis.
Therefore, activation of the complement system is a direct functional mechanism of immunoglobulins.

Step 3: Final Answer:
One of the primary functions of immunoglobulins is the Activation of the complement system.