Figure 1: NK Cell Stimulation In-vivo
The Function of NK Cells
NK cells, also known as large granule lymphocytes (LGL) are a type of cytotoxic lymphocyte that can directly attack cancer cells. The cytotoxicity of NK cells, can be demonstrated in several ways. One of the most important known mechanisms of the NK cells, when attacking and adhering to the receptors of the cancer cells, is the release of the perforin granules (6). Perforin is a protein released by NK cells that destroys targeted cells by creating lesions like pores in their membrane.
When these granules or NK Cells are injected directly into the cancer cells and perforate the cell membranes, they create an aqueous channel that permits the entry of another cytotoxic protease known as granzymes (7), which act to damage the DNA of the cancer cells and in turn, induce cell death through apoptosis. When activated, NK cells also have other mechanisms, such as releasing pro-inflammatory cytokines and interferons known as IFNy,
TNFa and IL-6 (8) that play a key role in the stimulation of other immune cells such as T-cells and macrophages (9), and in the maturation of dendritic cells (10). Thus, this increases even more, the killing of cancer cells.
NK cells patrol within the blood circulation at resting state, but when activated, they become voracious and can kill a cancer cell in 5 minutes and can repeat this process up to 27 times.