Editing Natural killer cell (section)

==Types==
NK cells can be classified as CD56<sup>bright</sup> or CD56<sup>dim</sup>.<ref name="pmid32545516">{{cite journal | vauthors = Hashemi E, Malarkannan S | title = Tissue-Resident NK Cells: Development, Maturation, and Clinical Relevance | journal = Cancers | volume = 12 | issue = 6 | pages = 1553 | date = June 2020 | pmid = 32545516 | pmc = 7352973 | doi = 10.3390/cancers12061553 | doi-access = free }}</ref><ref name="pmid32762681">{{cite journal | vauthors = Wu SY, Fu T, Jiang YZ, Shao ZM | title = Natural killer cells in cancer biology and therapy | journal = Molecular Cancer | volume = 19 | issue = 1 | pages = 120 | date = August 2020 | pmid = 32762681 | pmc = 7409673 | doi = 10.1186/s12943-020-01238-x | doi-access = free }}</ref><ref name="pmid32477340" /> CD56<sup>bright</sup> NK cells are similar to [[T helper cell]]s in exerting their influence by releasing [[cytokine]]s.<ref name="pmid32762681" /> CD56<sup>bright</sup> NK cells constitute the majority of NK cells, being found in bone marrow, secondary lymphoid tissue, liver, and skin.<ref name="pmid32477340" /> CD56<sup>bright</sup> NK cells are characterized by their preferential killing of highly proliferative cells,<ref>{{Cite journal |last1=Lee |first1=Mercede |last2=Bell |first2=Charles JM |last3=Rubio García |first3=Arcadio |title=CD56bright natural killer cells preferentially kill proliferating CD4+ T cells |url=https://academic.oup.com/discovimmunology/advance-article/doi/10.1093/discim/kyad012/7241354 |journal=Discovery Immunology |date=2023 |pages=kyad012 |doi=10.1093/discim/kyad012|doi-access=free |pmc=10465185 }}</ref> and thus might have an immunoregulatory role. CD56<sup>dim</sup> NK cells are primarily found in the [[Venous blood|peripheral blood]],<ref name="pmid32477340" /> and are characterized by their cell killing ability.<ref name="pmid32762681" /> CD56<sup>dim</sup> NK cells are always [[CD16]] positive (CD16 is the key mediator of [[antibody-dependent cellular cytotoxicity]], or ADCC).<ref name="pmid32762681" /> CD56<sup>bright</sup> can transition into CD56<sup>dim</sup> by acquiring CD16.<ref name="pmid32477340" />

NK cells can eliminate virus-infected cells via CD16-mediated ADCC.<ref name="pmid32655581">{{cite journal | vauthors = Market M, Angka L, Martel AB, Bastin D, Olanubi O, Tennakoon G, Boucher DM, Ng J, Ardolino M, Auer RC | display-authors = 6 | title = Flattening the COVID-19 Curve With Natural Killer Cell Based Immunotherapies | journal = Frontiers in Immunology | volume = 11 | pages = 1512 | year = 2020 | pmid = 32655581 | pmc = 7324763 | doi = 10.3389/fimmu.2020.01512 | doi-access = free }}</ref> All [[coronavirus disease 2019]] (COVID-19) patients show depleted CD56<sup>bright</sup> NK cells, but CD56<sup>dim</sup> is only depleted in patients with severe COVID-19.<ref name="pmid32655581" />