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+ NK cells possess a unique ability to elicit an immune response without the presence of immunoglobulins (Ig) and MHC molecules, but simply through the identification of stressed cells, or through the hypothesized “missing self” in which the NK cell senses the downregulation of the surface MHC molecules which usually accompanies certain intracellular infections.
CD56+ NK cells are isolated from mononuclear cells by positive selection using an antibody that targets the CD56 antigen.
For cryopreserved CD56+ NK cells, either prepare cells for long-term storage in Liquid Nitrogen vapor phase or thaw for use. Storage in liquid phase nitrogen is NOT recommended. Short-term storage of cells (less than 2 weeks) at -80°C is acceptable but should be minimized to ensure maximum stability. Once thawed, samples must be used immediately.
Testing: Donors are tested for HBV, HCV, HIV, HTLV, WNV, Trypanasoma cruzi, and Syphilis.