Which of the following statements about natural killer cells is false?

• A. Natural killer cells can recognize stressed cells in the absence of antibodies.
• B. Natural killer cells require prior sensitization to recognize and destroy target cells.
• C. Natural killer cells are a type of lymphocyte involved in the innate immune response.
• D. Natural killer cells can induce apoptosis in virus-infected cells.

Answer: (B)

Verified step by step guidance

1. Understand the role of natural killer (NK) cells in the immune system. NK cells are part of the innate immune response, meaning they act quickly and do not require prior exposure to a pathogen to respond.
2. Recognize that NK cells can identify stressed cells, such as those infected by viruses or undergoing transformation into cancer cells, without the need for antibodies. This is a key feature of their function in the innate immune system.
3. Learn that NK cells can induce apoptosis, which is a programmed cell death, in virus-infected cells. This helps to prevent the spread of the virus within the body.
4. Identify the false statement: 'Natural killer cells require prior sensitization to recognize and destroy target cells.' This statement is incorrect because NK cells do not need prior sensitization; they can act immediately upon recognizing stressed or abnormal cells.
5. Review the characteristics of NK cells: they are lymphocytes involved in the innate immune response, can recognize stressed cells without antibodies, and can induce apoptosis in infected cells. These features distinguish them from other immune cells that require prior sensitization.