Natural Killer Cells. Natural Killer (NK)Cells are lymphocytes in the same family as T and B cells, coming from a common progenitor. However, as cellsof the innate immune system, NK cellsare classified as group I Innate Lymphocytes (ILCs) and respond quickly to a wide variety of pathological challenges.

Natural Killer (NK) cells are a type of lymphocyte that plays a critical role in the innate immune response. They are part of the immune system and work alongside other immune cells to protect the body from infections and various types of cancer.

Function and Mechanism
NK cells are primarily involved in detecting and destroying cells that are infected with viruses or have become cancerous. Unlike other immune cells, they do not require prior exposure to a specific pathogen to initiate a response. NK cells recognize and target cells that display abnormal or missing surface proteins, a common feature of cancer cells and infected cells.

NK cells have the ability to kill their targets directly by releasing cytotoxic molecules, such as perforin and granzyme, which cause cell death. They can also induce apoptosis (programmed cell death) in target cells by activating certain receptors on their surface. Additionally, NK cells produce cytokines, which are signaling molecules that help to coordinate the immune response.

Activation and Regulation
NK cells can be activated by several mechanisms, including cytokines secreted by other immune cells and specific binding to target cells. They are regulated by a balance of activating and inhibitory signals received through various receptors on their surface.

Deficiencies in NK cell function have been associated with increased susceptibility to infections and cancer. On the other hand, hyperactivation of NK cells can lead to autoimmune disorders and tissue damage.

In summary, NK cells are a crucial component of the innate immune system, providing rapid and non-specific defense against infected or cancerous cells. They are regulated by a complex system of activating and inhibitory signals and play a critical role in maintaining immune homeostasis.