A natural killer cell, commonly abbreviated as NK cell, is a specific type of lymphocyte, which is a white blood cell involved in the immune response. These cells are a critical component of the body's innate immune system, responsible for detecting and eliminating virus-infected cells, as well as cancerous cells. Unlike other immune cells, natural killer cells are not antigen-specific, meaning they do not require prior exposure to a specific pathogen to recognize and target it.
NK cells are defined by their ability to directly induce cell death, known as apoptosis, in target cells. They accomplish this through the release of specialized proteins called perforins and granzymes. Perforins create pores in the target cell's membrane, allowing the entry of granzymes, which then initiate a cascade of events leading to the cell's death. These characteristics give NK cells their name, as they are "natural" killers of cells that pose a threat to the body.
Natural killer cells play a vital role in immune surveillance, constantly patrolling the body to detect abnormal or infected cells. They are particularly efficient at eliminating tumor cells and virally infected cells, making them an important component of the body's defense against cancer and viral infections. In addition to their cytotoxic capabilities, NK cells also produce immune regulatory proteins, known as cytokines, that stimulate and regulate other immune cells, further enhancing the immune response.
Overall, natural killer cells are an integral part of the immune system, due to their ability to recognize and destroy aberrant cells without requiring prior immune sensitization. Their capacity to eliminate virus-infected cells and cancerous cells make them a critical component of the body's defense mechanisms.
