What is the main role of natural killer cells in the immune system?

Natural killer (NK) cells play a crucial role in the innate immune system, primarily involved in the body's first line of defense against tumors and virally infected cells. Their main function is to identify and destroy these abnormal cells without the need for prior sensitization to specific antigens.

NK cells possess a unique capability to recognize stressed or transformed cells via various surface receptors. Once they identify a target, they can induce apoptosis, or programmed cell death, in those cells. This direct cytotoxic mechanism is significant for preventing the spread of infections and tumor growth, effectively contributing to the immune surveillance.

While other immune cells, such as B cells, are responsible for producing antibodies and T cells for mediating immune responses, NK cells are specifically designed for rapid response to eliminate compromised cells. Their activity is a vital component of the body's defense against malignancies and viral pathogens, underscoring their importance in maintaining health and homeostasis within the immune system.