Question

Which of the following is a component of innate immunity?

• A. Memory B cells
• B. Cytotoxic T cells
• C. Natural killer cells
• D. Plasma cells

Hint:

Remember: \[ \boxed{ \text{Innate Immunity} = \text{NK Cells} + \text{Macrophages} + \text{Neutrophils} + \text{Complement System} } \] NK cells act rapidly and do not require previous exposure to an antigen.

Answer 1

The Correct Option is C

Concept: The immune system is divided into innate immunity and adaptive immunity. Innate immunity provides immediate, non-specific defense against pathogens, whereas adaptive immunity is antigen-specific and develops immunological memory. Natural Killer (NK) cells are an important component of innate immunity because they destroy virus-infected and cancerous cells without prior sensitization.

Step 1: Understand innate immunity.
Innate immunity is characterized by:
• Immediate response
• Non-specific defense
• No immunological memory
• Present from birth Major components include:
• Physical barriers
• Phagocytic cells
• Natural Killer (NK) cells
• Complement proteins

Step 2: Role of Natural Killer cells.
NK cells:
• Kill virus-infected cells.
• Destroy tumour cells.
• Release perforin and granzymes.
• Act without prior antigen exposure. Thus, they provide rapid protection during the early stages of infection.

Step 3: Eliminate incorrect options.

• Memory B cells belong to adaptive immunity.
• Cytotoxic T cells are adaptive immune cells.
• Plasma cells are differentiated B cells that produce antibodies.
• Only Natural Killer cells belong to innate immunity. Final Answer: \[ \boxed{Option (C) is correct \]