Which immune component binds iron to limit pathogen growth?

Which immune component binds iron to limit pathogen growth?

• A. Interferon
• B. Lysozyme
• C. Macrophages
• D. Lactoferrin

Answer: (D)

Lactoferrin works through nutritional immunity, a defense strategy where essential nutrients like iron are limited for invading microbes. This iron-binding protein is abundant in secretions (such as milk and mucous) and in neutrophils. It clings to ferric iron very tightly, lowering the amount of free iron available in the local environment. Since many pathogens need iron for growth and metabolism, this sequestration slows or halts their proliferation. In addition to iron binding, lactoferrin can have direct antimicrobial effects, but its primary role here is depriving pathogens of iron. The other options serve different immune functions—interferon initiates antiviral responses, lysozyme breaks down bacterial cell walls, and macrophages ingest and destroy pathogens—without primarily limiting iron availability.

Lactoferrin works through nutritional immunity, a defense strategy where essential nutrients like iron are limited for invading microbes. This iron-binding protein is abundant in secretions (such as milk and mucous) and in neutrophils. It clings to ferric iron very tightly, lowering the amount of free iron available in the local environment. Since many pathogens need iron for growth and metabolism, this sequestration slows or halts their proliferation. In addition to iron binding, lactoferrin can have direct antimicrobial effects, but its primary role here is depriving pathogens of iron. The other options serve different immune functions—interferon initiates antiviral responses, lysozyme breaks down bacterial cell walls, and macrophages ingest and destroy pathogens—without primarily limiting iron availability.