This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
[{'content': 'True statement regarding NK cells are all except: \nSelect and explain. \nA. No role in cell mediated immunity, B. Form part of innate immunity, C. CD 16 positive, D. CD 56 positive', 'role': 'user'}, {'content': 'Answer: A \nExplanation: "NK cell: They have CD 16 & CD 56 on their surface. They release several cytolytic factors; one of these, perforins, which resembles complement C9, cause transmembrane pores through which cytotoxic factor\xa0enter the cell. NK cell activity is augmented by interferon"\n- Ananthanarayan 8/131\n" N K cell: Farm part of innate immunity as it does not require prior sensitisation by antigen. Their\xa0cytotoxicity is not antibody dependent or MHC restricted."\n- Ananthanarayan 8/131\nLARGE GRANULAR LYMPHOCYTES/NATURAL KILLER CELLS\n- Harrison l7/ 2024-29\n\nLarge granular lymphocytes (LGLs) or NK cells account for ~5-10% of peripheral blood lymphocytes.NKs cells are nonadherent, nonphagocytic cells with large azurophilic cytoplasmic granules.\nNKs cells express surface receptors for the Fc portion of IgG (CD16) and for NCAM-1 (CD56), and\xa0many NK cells express some T lineage markers, particularly CD8, and proliferate in response to IL-2.\xa0NK cells arise in both bone marrow and thymic microenvironments\nFunctionally, NK cells share features with both monocytes-macrophages and neutrophils in that they\xa0mediate both antibody-dependent cellular cytotoxicity (ADCC) and NK cell activity.\nNK cell activity may play an important role in immune surveillance and destruction of malignant and virally infected host cells\nNK cell hyporesponsi%reness is also observed in patients with Chediak-Higashi syndrome, an autosomal\xa0recessive disease associated with fusion of cytoplasmic granules and defective degranulation of\xa0neutrophil lysosomes.\nThe ability\' of NK cells to kill target cells is inversely related to target cell expression of MHC class l\xa0molecules.\nTo eliminate malignant and virally infected cells. NK cells also require activation through recognition of\xa0NK activation molecules on the surface of target cells.\nRecent evidence suggests that NK cells, though not possessing rearranging immune recognition genes,\xa0may be able to mediate recall responses for certain immune reactions such as contact hypersensitivity.\nSome NK cells express CD3 and are termed NK/T cells\\ NK/T cells can also express oligoclonal forms\xa0of the TCR for an antigen that can recognize lipid molecules of intracellular bacteria when presented in the\xa0context of CD 1 molecules on A PCs. This mode of recognition of intracellular bacteria such as Listeria\xa0monocytogenes and M. tuberculosis by NK/T cells leads to induction of activation of DCs and is thought\xa0to bean important defence mechanism against these organisms', 'role': 'assistant'}]