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Functional Natural Killer (NK) Assays with Prednisolone
Principle
Natural killer (NK) cells, also known as large granular lymphocytes, are mononuclear cells that mediate cytolysis of cells lacking MHC Class I or Class II molecules. They also regulate the immune response, contribute to natural resistance against tumor cells, and produce cytokines.
Mononuclear cells (containing lymphocytes with natural killer activity) are incubated for 2 hours with K562 target cells that have been pre-stained with PKH-2, a lipophilic dye that binds to the cell membrane and fluoresces green. When K562 cells are killed by NK cells, they become permeabilized, allowing propidium iodide to enter and fluoresce bright red/orange. The percentage of killed target cells containing propidium iodide is measured by flow cytometry.
When lymphocytes are incubated with target cells in the presence of IVIG, Intralipid, or Prednisolone, inhibition of cytotoxicity may be observed.
Specimen Requirements
Specimen
Collection
Storage and Transport
Send at room temperature. Do not refrigerate. Deliver to the laboratory within 24 hours.
Unacceptable Specimens
- Cold specimens (refrigerated or shipped on ice)
- Specimens with extensive clotting or hemolysis
- Specimens older than 48 hours
If a specimen exceeds 48 hours, lymphocytes will be isolated and viability assessed. If viability is >80%, the assay will be performed; if <80%, the specimen will be rejected.
Method
Flow Cytometry
Turnaround Time
Note
The Natural Killer Assay with Prednisolone may only be performed in conjunction with one of the following:
- Natural Killer Assay Full Panel
- Natural Killer Assay Follow-up
- Natural Killer Assay Inhibition Panel
References
- Trinchieri, G. Biology of Natural Killer Cells. Adv. Immunol. 47:187-376;1989
- Starkey, P.M., Sargent, I.L., Redman, C.W.G. Cell population in human early pregnant decidua: Characterization and isolation of large granular lymphocytes by flow cytometry. Immunology 65:129;1988
- Gilman-Sachs, A., DuChateau., B.K., Aslakson, C.J., Wohlgemuth, G.P., Kwak, J.Y., Beer, A.E., and Beaman, K.D. Natural Killer (NK) cell subsets and NK cell cytotoxicity in women with histories of recurrent spontaneous abortions. Am. J. Repro. Immunol. 41: 99-105; 1999.