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Defence against bacteria - Innate immunity - NK-cells

8 important questions on Defence against bacteria - Innate immunity - NK-cells

What is the difference between ILC1 cells and NK cells?

NK cells are more like CD8 T cells and ILC1 are more like CD4 T cells. NK cells can be found in tissues, but they also circulate through the blood while the ILC1 cells appear to be largely non-circulating tissue resident cells.

What is the role of NK cells in the defense against viruses?

o They recognize and kill infected cells.
o Produce IFN-gamma and TNFa
o NK cells kill via ADCC

How can a NK cell kill infected cells but not normal cells?

This happens via inhibitory and activating receptors and signals. NK cell has multiple inhibitory receptors that recognizes MHC class I on the cell that inhibit signals from activating receptors which will result in not killing normal cells. When the MHC-I is not available at the cell surface the negative signal cannot be regenerated which results in killing the cell.

How do NK cells recognize and kill the infected cells?

NK cells can release granule contents which induces apoptosis in a target cell.

Which are the receptors that regulate the activity of NK cells?

Killer cell immunoglobulin0like receptor family (KIR) are part of a larger cluster or receptors the leukocyte receptor complex (LRC)
Killer cell lectin-like receptors (KLR) reside whitin a gene cluster called the NK receptor complex (NKC)
Natural cytotoxic receptors (NCRs)

How can NK cells kill via the ADCC?

This is antibody-dependent cellular cytotoxicity, this happens when IgG antibodies bind to the Fc receptors (FCG3) on the surface of the NK cells which induced the NK cell to release their cytotoxic granules.

Where do NK serve for in a virus infection?

The NK cells serve to contain a virus infection while the adaptive immune response is generating antigen specific cytotoxic T-cells a neutralising antibody that can really clear the virus infection

How can a NK cell kill via TNFR family receptor?

When an infected cell express TRAIL which is a part of the TNFR family receptor the DR4/5 of the NK cell can bind to this receptor. This sets of a pathway in which through FAD induces the pro-caspase 8 which leads to the induction of apoptosis of the target cell.

The question on the page originate from the summary of the following study material:

Immunology

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