Which of the following is NOT considered a component of the innate immune system in humans?

• A. Antibodies
• B. Lysozyme enzyme
• C. Phagocytic cells
• D. Skin barrier

Answer: (A)

Verified step by step guidance

1. Understand the difference between the innate and adaptive immune systems. The innate immune system provides immediate, non-specific defense against pathogens, while the adaptive immune system provides a specific response and memory.
2. Identify components of the innate immune system. These include physical barriers like the skin, chemical barriers such as lysozyme enzyme found in secretions, and cellular defenses like phagocytic cells (e.g., macrophages and neutrophils) that engulf pathogens.
3. Recognize that antibodies are proteins produced by B cells as part of the adaptive immune system. They specifically recognize and bind to antigens, which is a targeted response rather than a general one.
4. Compare each option to the characteristics of the innate immune system. Skin barrier, lysozyme enzyme, and phagocytic cells are all innate components, while antibodies are not.
5. Conclude that antibodies are NOT part of the innate immune system because they are produced by the adaptive immune system in response to specific antigens.