What is the function of natural killer (NK) cells?
To provide immunity against intracellular infections.
Natural killer cells (NK cells) are the killer lymfocytes of the innate immune system. Their role is to provide immunity against intracellular infections. NK cells have two ways to perform this task: kill infected host cells and/or secrete cytokines (proteins that aid the immune response).
NK cells provide a 'quick and dirty' response to an infection, preceding and complementing the slower, but more specific response of the cytotoxic T-cells of the adaptive immune system. Both types of lymfocytes are trained and equiped to recognize and kill (virally) infected host cells.