Lecture 8: Natural Killer Cells Flashcards
What are natural killer cells good at ?
Killing virally infected cells
What type of response do you want to a viral infection and why ?
Th1 as it produces intereferon gamma
What is an effector cell ?
Carry out end-stage jobs in the innate immune system
What are the regulators of the adaptive immune system ?
Cell-cell contact or cytokines
What are natural killer cells distinguished by ?
Cell surface molecules
What is a marker on all cells
CD3
What is the marker on natural killer cells ?
CD56 and or CD16
What are natural killer cells characterised by ?
Granules in their cytoplams
Do natural killer cells have thymus development ?
NO
What are natural killer cells important in ?
Effector cells in viral infections and cancer where they mediate cytotoxicity
What do natural killer cells produce ?
Cytokines which activate other cells of the immune system
What do natural killer cells recognise and kill ?
Tumour cells in vitro and in vivo
What activates natural killer cells ?
IL2
What does IL2 which activates NK cells generate ?
Lymphokine activated killers (LAK)
What do NK cells produce ?
- IFN-gamma
- TNF-alpha
- TGF-beta
- G-CSF
- GM-CSF
- IL3
What are the first cytokines produced by macrophages and dendritic cells ?
- IFN-gamma
- IL12
- TNF-alpha
What does NK cells regulate ?
- Haemopoiesis
- Antibody isotype switching
How does NK regulate haemopoiesis ?
Through colony stimulating factors and IL3
What does antibody isotype switching occur through ?
IFN-gamma
How do cytotoxic effector cells kill their targets ?
- Necrosis
- Apoptosis
What is necrosis ?
Non-physiological insult to cell which results in membrane damage and osmotic lysis. Associated with inflammation as cell contents leak out
What is apoptosis ?
Physiological form of cell death
How is programmed cell death activated ?
- DNA fragmentation
- Formation of apoptotic bodies
What do granules contain to kill cells ?
- Perforin
- Granzymes
What is perforin ?
Pore forming proteins
What is granzymes ?
Serine proteases
What happens upon target cell binding ?
Cytotoxic cell rearranges its organelles to bring cytotoxic granules to the immunological synapse with target cell
What is lymphotoxin ?
Membrane bound version of TNF
What can cytotoxic cells do to themselves ?
Recycle themselves and kill more target cells
What do T cells and NK cells recognise ?
MHC 1 antigen
What are t cells activated by ?
MHC I
What are NK cells inhibited by ?
MHC I
