Natural Killer Cells Flashcards
What are natural killer cells?
Are a subset of innate like lymphocytes with cytotoxic activity.
How do NK cells kill?
Through release of perforin and granzyme that they produce in intracellular vesicles (perforin punctures the pores in cell membrane and granzymes enters via these pores to kill the target cell).
What are NK cells important mediators off?
Anti-viral and anti-tumour response
What cytokines do NK cells produce to modulate immune response?
IFN-gamma
What do human NK cells express to be identified?
CD56
What do CD56 bright NK cells produce?
Cytokines
What are CD mid NK cells?
Cytotoxic cells
Can NK celsl lack CD56?
Yes
How are murine NK cells be identified?
NK1.1 and NKp46
How are NK celsl activated?
They are exposed to both activatory signals and inhibitory signals as the go around the body and to activate them they need to see more activatory signals and less inhibitory signals
What happens when NK cells bind to self MHC?
They are usually inhibited from being activated
What happens if the MHC is missing? (this can be caused by pathogens in the cell downregulating MHC)?
They are activated and release immune mediators or cytotoxic granules to kill their target.
If the MHC are foreign will the NK cells still be inhibited?
No
Is only missing MHC enough for NK cells to be activated?
No - as blood cells do not have MHC, they need other signals
Why would MHC be downregulared in cells?
Viruses downregulate MHC 1 do get rid off the T cell response
When tumours form they proliferate at the same speed of other cells as they are stopped by the immune system. They will then downregulate MHC so they can overproliferate.
