What do Natural Killer (NK) cells produce to induce lysis and apoptosis?

• A. Perforins
• B. Defensins
• C. Kinins
• D. Histamines

Answer: (A)

Natural Killer (NK) cells play a crucial role in the innate immune response by recognizing and destroying infected or cancerous cells. The correct answer is perforins. These proteins are released by NK cells and form pores in the target cell membranes. By doing so, perforins create channels that enable the entry of granzymes, which are serine proteases that trigger apoptosis (programmed cell death) in the target cells.

Through this mechanism, NK cells effectively eliminate potentially harmful cells without requiring prior sensitization to a specific antigen. This rapid response is essential for the early defense against viral infections and tumorigenesis, highlighting the importance of perforins in the function of NK cells. Understanding this process underscores the critical role of NK cells in maintaining the body's immune surveillance and response.