True statement regarding NK cells are all except:
Correct Answer: No role in cell mediated immunity
Description: "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 enter the cell. NK cell activity is augmented by interferon"
- Ananthanarayan 8/131
" N K cell: Farm part of innate immunity as it does not require prior sensitisation by antigen. Their cytotoxicity is not antibody dependent or MHC restricted."
- Ananthanarayan 8/131
LARGE GRANULAR LYMPHOCYTES/NATURAL KILLER CELLS
- Harrison l7/ 2024-29
Large 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.
NKs cells express surface receptors for the Fc portion of IgG (CD16) and for NCAM-1 (CD56), and many NK cells express some T lineage markers, particularly CD8, and proliferate in response to IL-2. NK cells arise in both bone marrow and thymic microenvironments
Functionally, NK cells share features with both monocytes-macrophages and neutrophils in that they mediate both antibody-dependent cellular cytotoxicity (ADCC) and NK cell activity.
NK cell activity may play an important role in immune surveillance and destruction of malignant and virally infected host cells
NK cell hyporesponsi%reness is also observed in patients with Chediak-Higashi syndrome, an autosomal recessive disease associated with fusion of cytoplasmic granules and defective degranulation of neutrophil lysosomes.
The ability' of NK cells to kill target cells is inversely related to target cell expression of MHC class l molecules.
To eliminate malignant and virally infected cells. NK cells also require activation through recognition of NK activation molecules on the surface of target cells.
Recent evidence suggests that NK cells, though not possessing rearranging immune recognition genes, may be able to mediate recall responses for certain immune reactions such as contact hypersensitivity.
Some NK cells express CD3 and are termed NK/T cells NK/T cells can also express oligoclonal forms of the TCR for an antigen that can recognize lipid molecules of intracellular bacteria when presented in the context of CD 1 molecules on A PCs. This mode of recognition of intracellular bacteria such as Listeria monocytogenes and M. tuberculosis by NK/T cells leads to induction of activation of DCs and is thought to bean important defence mechanism against these organisms
Category:
Pathology
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