II. Physiology

  1. Background
    1. Lymphocytes providing protection against Intracellular Bacteria and viruses, as well as cancer cells
      1. Respond to intracellular Viral Infections within first 3 days
      2. Similar destruction of virally infected cells as with Cytotoxic T Cells
    2. Part of Innate Immunity in which response is not based on prior exposure to pathogen
      1. Contrast with antibodies, B-Cells and T-Cells which have a learned pathogen response (Adaptive Immunity)
      2. Lack the Specificity of Adaptive Immunity
      3. Do not require MHC markers on Target Cells (unlike other Lymphocytes)
        1. In contrast, NK cells appear to Target Cells without MHC Proteins
    3. Natural Killer Cell Markers
      1. CD56 positive
      2. CD3 negative
      3. Lack other markers found on B Cells and T Cells
  2. Activation of Natural Killer Cells
    1. Macrophage and Dendritic Cell derived Cytokines (e.g. Interleukin 12, type 1 Interferons)
  3. Deactivation of Natural Killer Cells
    1. Natural Killer Cells bind Major Histocompatibility Complex 1 (MHC-1)
    2. MHC-1 is present on normal cells and it inactivates NK cells
    3. MHC-1 is NOT expressed by infected cells
      1. NK activating receptor Ligand is expressed
      2. NK cells bind infected cells and destroy them
  4. NK cell mechanisms of infected cell destruction
    1. Cytoplasmic granules released, resulting in Target Cell lysis
      1. Perforin
        1. Generates pores on cells targeted for destruction
      2. Granzyme
        1. Induces programmed cell death (apoptosis) on entry into Target Cells
    2. Cytokines
      1. Tumor Necrosis Factor A (TNFa)
      2. Granulocyte Macrophage Colony Stimulating Factor (GM-CSF)
      3. Chemokines (CCL1-5 and CCL-8)
      4. Interferon-Gamma (IFN-g)
        1. Activates Macrophages for Phagocytosis
  5. Image: NKC Mediated Destruction of Infected Host Cells
    1. NaturalKillerCells.jpg

III. References

  1. Guyton and Hall (2006) Medical Physiology, p. 419-50
  2. Mahmoudi (2014) Immunology Made Ridiculously Simple, MedMaster, Miami, FL

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Related Studies

Ontology: Natural Killer Cells (C0022688)

Definition (MSH) Bone marrow-derived lymphocytes that possess cytotoxic properties, classically directed against transformed and virus-infected cells. Unlike T CELLS; and B CELLS; NK CELLS are not antigen specific. The cytotoxicity of natural killer cells is determined by the collective signaling of an array of inhibitory and stimulatory CELL SURFACE RECEPTORS. A subset of T-LYMPHOCYTES referred to as NATURAL KILLER T CELLS shares some of the properties of this cell type.
Definition (MSHCZE) Lymfocyty získané z kostní dřeně, které mají cytotoxické vlastnosti, přirozeně namířené proti transformovaným buňkám a buňkám infikovaným virem. NK buňky nejsou na rozdíl od T buněk a B buněk antigenově specifické (projevuje se nespecifickou imunitou). Cytotoxicita těchto buněk je zajištěna pomocí receptorů na povrchu buněk, které společně signalizují stavy inhibice a stimulace buněk. Jedná se o podskupina T-LYMPHOCYTŮ, která bývá označována jako „přirození zabíječi“ (NKT BUŇKY) (angl. natural killers) a sdílí s těmito buňkami některé vlastnosti. R
Definition (NCI) Natural killer cells are cells that resemble large granular lymphocytes. They do not express markers of either T or B cell lineage. They are positive for CD16, CD56, and CD 94. These cells do possess Fc receptors for IgG and can kill target cells using antibody-dependent cell-mediated cytotoxicity. They can also use perforin to kill cells in the absence of antibody and killing may occur without previous sensitization.
Definition (NCI_NCI-GLOSS) A type of immune cell that has granules (small particles) with enzymes that can kill tumor cells or cells infected with a virus. A natural killer cell is a type of white blood cell.
Definition (PSY) White blood cells that kill tumor- and virus-infected cells as part of the body's immune system.
Definition (CSP) type of cytotoxic leukocytes which attack and kill virus-infected or neoplastic cells independent of antibody coating or MHC restriction; may be derived from lymphocytes or monocytes.
Concepts Cell (T025)
MSH D007694
SnomedCT 259717003
LNC LA4573-7
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Spanish célula NK, linfocito K, Células Asesinas Naturales, Células Killer Naturales, célula natural killer, célula asesina natural, Células Killer, linfocito citolítico natural (célula), linfocito citolítico natural, Células NK
French Cellule tueuse naturelle, Cellules tueuses naturelles, Cellules NK, Cellule NK
Swedish Mördarceller, naturliga
Czech buňky NK, buňky natural killer
Finnish Luonnolliset tappajasolut
Italian Cellule NK, Cellule Natural Killer
Japanese NK細胞, キラー細胞-ナチュラル, ナチュラルキラー細胞
Polish Komórki NK, Komórki natural killer, Komórka-naturalny zabójca, Komórki naturalnej cytotoksyczności
Norwegian Natural killer-celler, Drepeceller, naturlige, Naturlige drapsceller, Drapsceller, naturlige, Naturlige drepeceller, NK-celler
Portuguese Células Exterminadoras, Células Destruidoras, Células Killer, Células Natural Killer, Células Destruidoras Naturais, Células Assassinas, Células Killer Naturais, Células Assassinas Naturais, Células Exterminadoras Naturais, Células NK, Células Matadoras Naturais
German NK-Zellen, Killerzellen, natürliche, Natürliche Killerzellen
Dutch K-cel, Killercellen, Natural-killercel, Natural-killercellen