Killer Cell

About NK cells/ Killer Cell:

Natural killer cells, also known as NK cells or large granular lymphocytes (LGL), are a type of cytotoxic lymphocyte important to the innate immune system. They belong to the rapidly growing innate lymphoid cell (ILC) family and account for 5–20 percent of all circulating lymphocytes in humans. NK cells play a similar function to cytotoxic T cells.

NK cells Mechanism
NK cells react quickly to virus-infected cells, starting to function three days after infection, and they also respond to tumour formation. Immune cells sense the major histocompatibility complex (MHC) on infected cell surfaces, which triggers the release of cytokines, which causes the infected cell to die through lysis or apoptosis.
They were given the name "natural killers" because they destroy cells that lack MHC class 1 "self" markers without the need for activation. This role is critical since dangerous cells lacking MHC I markers cannot be identified and killed by other immune cells, such as T lymphocyte cells.

Killer Cell Function
The function of the NK cells includes; cytolytic granule-mediated cell apoptosis, antibody-dependent cell-mediated cytotoxicity (ADCC), Cytokine-induced NK, and Cytotoxic T lymphocyte (CTL) activation, tumour cell surveillance and clearance of senescent cells.
The ability of T and B cells to produce memory cells after a primary infection, as well as the subsequent rapid immune activation and response to subsequent infections by the same antigen, is critical to the adaptive immune response. For a long time, NK cells were thought to be part of the innate immune system. However, new evidence indicates that NK cells may exhibit many characteristics that are normally associated with adaptive immune cells, e.g., T cell responses.