Human Natural Killer (NK Cells)
Natural killer cells (NK cells) are cytotoxic members of the innate immune system. CD56 NK cells are a major component of the immune system. CD56+ NK cells play a key role in the rejection of tumors and cells infected by viruses; killing by releasing perforin and granzymes that cause the target cell to die by apoptosis. CD56+ cells are isolated from leukopaks by positive or negative selection (NS) using immunomagnetic cell separation procedures. NK cells that are positively selected using the CD56 antigen will include a mixed population of NK and NKT cells.