A set of cytotoxic lymphocytes was discovered in the peripheral blood (PB) of rodents that differed in several key ways from cytotoxic T lymphocyte (CTLs). These cells lacked several cell surface markers of T cells. In addition, they were active even after isolation from unimmunized animals in lysing many different tumor cell lines. Because the newly discovered cytotoxic cells did not require specific immunization, they were termed 'natural killer cells' (NK cells). Soon after, also in the PB of humans, lymphocytes that shared the same characteristics of murine NK cells were described. Today, we know that NK cells are large granular lymphocytes distinct from B cells and T cells, able to kill according to a mechanism regulated by several activating and inhibiting receptors. They can detect the loss of major histocompatibility complex (MHC) molecules or the presence of olecules induced upon stress. This feature confers them a potential role in cancer immune surveillance and in the control of viral infections. The majority of total human NK cells reside in human secondary lymphoid organs such as lymph nodes (LNs) or spleen. These tissues are specifically enriched in CD56bright NK cell subsets that seem to precede the terminal mature subset mainly found in the blood, that is CD56dim. This finding, in association with the discovery at this site of presumed maturing NK cell intermediates, suggests that secondary lymphoid organs are the primary sites where NK cells develop. Very limited studies have been performed, investigating the distribution of NK cells associated with human non-lymphoid peripheral compartments. Only little information is available on NK localization throughout the body, as well as regarding the mechanisms governing their trafficking during pathologic situations.
|Title of host publication||Natural Killer Cells|
|Number of pages||15|
|Publication status||Published - 2010|
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)