What is the primary function of perforins produced by natural killer cells?

Perforins produced by natural killer (NK) cells play a crucial role in the immune response, particularly in the elimination of cancerous cells and cells infected by viruses. When NK cells identify a target cell—such as a tumor cell or a virus-infected cell—they release perforins, which are pore-forming proteins. These perforins insert themselves into the target cell's membrane, creating pores that disrupt the cell's integrity. This disruption allows for water and ions to enter the target cell uncontrollably, ultimately leading to cell lysis (death).

This specific function of perforins makes them vital components in the body's defense mechanism against malignancies and viral infections, showcasing how the immune system can directly attack and eliminate harmful cells.