Natural killer cells

Question	Answer
What are natural killer cells?	Large, granular lymphocytes.
What proportion of lymphocytes in peripheral blood do natural killer cells constitute?	5-10%
Which cells do natural killer cells display cytotoxic activity against?	A wide range of tumour cells and cells infected with most (but not all) viruses.
Natural killer cells do not recognise tumour cells or virally infected cells by antigen as they do not have toll-like receptors or immunoglobulin in their cell membranes. How do they recognise their potential targets?	They have natural killer cell receptors (NKCRs) which distinguish changes abnormalities such as reduction in the display of MHC class I molecules on cell surfaces, or the unusual antigenic profile of the surfaces of some tumour and virus-infected cells. They also have CD16 receptors which bind to antibody, so if an antibody response has been raised, this can encourage natural killer cell involvement. This is antibody-dependent cell-mediated cytotoxicity.
What do natural killer cells look like when attack infected/tumour cells?	Image: nkcell (image/png)

Resource summary

	Created by sophietevans about 10 years ago