Natural killer (NK) cells play a key role in the innate immune system. These lymphocytes react to certain infections and malignancies by direct cytolysis of infected or transformed cells and by secretion of potent immune mediators. NK cells have the ability to recognize foreign or stressed cells that lack antibodies and major histocompatibility complex (MHC) class I proteins on the surface, which would normally go undetected by other immune cells. However, NK cells express an array of inhibitory receptors that recognize self-molecules. If not restrained by inhibitory receptors recognizing MHC class I proteins on the surface of self-cells, NK cells are able to kill normal, healthy cells.
Human peripheral blood CD56+ natural killer cells are enriched by means of negative selection. Cells expressing CD3, CD4, CD14, CD19, CD20, CD36, CD66b, CD123, HLA-DR, and CD235a are depleted from the mononuclear cell fraction by using immunomagnetic particles leaving purified, untouched CD56+ natural killer cells. Isolated cells are characterized by flow cytometry to ensure a highly pure and viable cell population. Positively selected natural killer cells are available as a custom order.
Cells were obtained using Institutional Review Board (IRB) approved consent forms and protocols.
Natural Killer Cells
HIV-, HepB-, HepC-
≥90% by Flow Cytometry
≥85% by Flow CytometryNote: For cryopreserved samples the freeze thaw cycle may decrease cell viability by 10-15% post thaw.
Fresh: PBS with 5% FBS and 0.5% BSAFrozen: CryoStor™ CS10 (10% DMSO)
Figure 1. Representative histogram of peripheral blood enriched CD56+ NK cells (97.91%) prior to cryopreservation.