Question

Which of the following pairs of milk constituents form the specific factors of antimicrobial systems in milk?

• A. Lactanins and immunoglobulins
• B. Lactanins and lysozyme
• C. Bifidus factor and lactoferrin
• D. Bifidus factor and complement

Hint:

Classification of milk antimicrobials:
- Specific $=$ Immunoglobulins (target specific antigens).
- Non-specific $=$ Lactenins (innate, broad-spectrum proteins like lactoferrin and lactoperoxidase).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Milk contains a variety of natural antimicrobial systems that protect the mammary gland from infection (mastitis) and help protect the newborn infant.
These systems are classified into specific immune factors and non-specific innate factors.
Detailed Explanation:
1. Specific Humoral Factors:
These factors belong to the adaptive immune system.
They target specific pathogens based on prior antigen exposure.
Immunoglobulins (antibodies such as IgG, IgA, and IgM) are the primary specific humoral factors in milk.
They bind specifically to target pathogens, neutralizing them or marking them for phagocytosis.
2. Non-specific (Innate) Factors:
These factors provide broad-spectrum protection and do not require prior exposure to a pathogen.
Examples include lactoferrin, lysozyme, and the lactoperoxidase system.
Historically, the non-specific inhibitory substances in milk were referred to collectively as lactenins (often spelled lactanins).
These lactenins include milk proteins like lactoperoxidase (L1), lactoferrin (L2), and other natural inhibitors.
Together, lactenins (representing non-specific innate immunity) and immunoglobulins (representing specific adaptive immunity) form the major antimicrobial systems in milk.
Let us review the other options:
- Lysozyme, lactoferrin, and the Bifidus factor (which promotes the growth of beneficial Bifidobacterium) are purely non-specific factors.
- While complement proteins are part of the immune system, the combination in Option A represents the established classification of milk's natural protective systems.

Step 2: Final Answer:
Lactanins and immunoglobulins are the key protective systems.