NK cells carry small granules in their cytoplasm which contain special proteins such as perforin and granzymes. When NK cells release perforin in close proximity to target cells (i.e., tumorous or virus-infected cells), it forms pores in the cell membrane of the target cell through which the granzymes and associated molecules can enter, apoptosis. Cytotoxic activity of NK cells is an important component of innate immunity which provides quick body response to cancerous or virus infected cells before more specialized adaptive immunity is generated.
