5 - NK cell Webcast Flashcards
Why are NK cells named as they are? Why are they considered a lymphocyte?
Because they are circulating lymphocytes that are capable of killing leukemic cells without needing previous exposure.
Considered a lymphocyte because they’re similar to TH cells, CTLs, and B cells ability to produce IFNY, and also like CTLs in their use of perforin and granzyme.
Why are NK cells considered innate?
Their function is dependent on activating receptors that are germline-encoded.
Not dependent on previous antigen exposure.
Define NK cells?
Class of lymphocytes that recognize infected and stressed cells and respond by killing these cells and secreting the macrophage-acting cytokine IFN-Y.
How abundant are NK cells in circulation?
Their concentration is low in the blood compared to other lymphocytes (<10%).
Do NK cells require MHC to kill their target cells?
No. Rather the NK cells recognition of MHC I inhibits their killing.
What do NK cells use to kill their targets?
Granzyme and perforin to apoptosis the target cell.
Also produce the cytokine IFN-Y.
What do NK cells target?
Virus-infected cells and tumor cells via IFN-Y in response to IL-2 being released by the infected cell.
NK cells are the principle mediators of _______?
Antibody-dependent cellular cytotoxicity (ADCC)
What cell surface markers can NK be stained with to identify via flow cytometry?
CD16 and CD56
CD2
CD3 negative (part of T cell receptor and NK cells don’t have this because they are not an adaptive immune cell)
How are NK cells activated?
By balance of activating receptors and inhibitory receptors on the NK cell surface and the balance of inhibitory ligands on the target cell.
How do granzymes enter the target cell?
Via receptor-mediated endocytosis and enter the cytoplasm via perforin dependent mechanisms to activate apoptotic pathways.
NK cells provide ______ to virus infection.
Resistance.
How do NK cells kill tumor cells?
NK cell binds to activating receptor on cell and then delivers perforin and granzyme into the tumor cell.
In the absence of NK cells, animals are more prone to _______?
Tumor development.
What is antibody-dependent cellular cytotoxicity (ADCC)?
Antibodies of certain IgG classes on infected cells have an FC portion that’s recognized be an FC receptor on NK cells.
This results in NK cell activation and killing of the antibody coated cell.
