Natural Killer Cells in Health and Disease

Natural Killer Cells are a type of _______

lymphocytes

Natural Killer Cells are similar to what type of T cells?

cytotoxic T cells

Cytotoxic T Cells are part of _____ immunity (system)

adaptive immunity (system)

_______ cells specifically target only one antigen

Cytotoxic T Cells

______ cells DO NOT specifically target one antigen but rather a wide variety of abnormal cell types

Natural Killer Cells

Natural Killer Cells are part of ______ immune system.

Innate Immune System

______ cells participate in immunological surveillance

Natural Killer Cells

______ def= to roam body and look for things that are abnormal (ie. listed below)

• invading pathogen

• virus infected cells

Immunological Surveillance

Virus infected cells fail to express _______

normal self MHC

How do Natural Killer Cells distinguish between Normal Self Cell (Healthy) and Bacterial Cell/Target Cell?

• Normal Self Cell (Healthy) displays its self antigen on its MHC 1 proteins on its cell surface

  • Bacterial Cell do not have MHC1 protein at all

• Natural Killer Cells look for proteins on surface of Normal Self Cells (healthy) and those proteins bind to Activation receptor of Natural Killer Cells

  • Activation Receptor will destroy Normal Self Cell if antigen on MHC1 protein of Target Cell is not recognized or displayed

• Natural Killer Cells also possess an Inhibitory receptor

  • Inhibitory receptor recognizes self antigen on MHC 1 protein of Normal Self Cell (Healthy)

  • Inhibits Natural Killer Cell from destroying Normal Self Cell (Healthy)

In Natural Killer Cells, what action outweighs what:

• Activation or Inhibition action?

Inhibition action outweighs

How do Natural Killer Cells destroy Bacterial Cells?

Natural Killer Cells contain:

• granules which contain proteins and enzymes

  • Perforins proteins= poke hole in target cell

  • Apoptotic Enzymes/ Caspases that can cause apoptosis in target cell

  • Granzymes and Granulysins= activate cast spaces in target cells to initiate apoptosis

Why do Natural Killer Cells destroy Target Cells via apoptosis?

allows virions to be killed within the target cell which prevents virions from spreading/infecting other cells

What do Natural Killer Cells contain which allows them to:

• causes apoptosis in target cells

Granulysins and Granzymes= induce apoptosis by activating cast spaces in target cells

Caspases/apoptotic enzymes= cause apoptosis in target cells

What do Natural Killer Cells contain which allows them to:

• poke hole in target cell

perforins

Granulysins and granzymes activate ______ in target cells and induce _____

activate cast spaces in target cells and induce apoptosis

Cytotoxic lymphocytes use _____ pathway similar to Natural Killer Cells

perforin pathway

• insert granulysins and granzymes and induce apoptosis

______ are the lethal weapon of immune system

Natural Killer Cells

Where do Natural Killer Cells from?

Hematopoietic Stem Cell —> Lymphoid Progenitor —> NK Cells

What important marker do NK cells express on its surface?

NK 1.1

What other markers are present on NK Cells?

• Fc receptors

  • for FC region of antibodies

• FASL receptors

  • fast ligand fast receptor mediated cell death

What receptor is a part of Natural Killer Cells’ Activated receptor?

NKG2D

• interacts with HLA E also binds with MIC-A, MIC-B and ULPB family members

What receptor is a part of Natural Killer Cells’ Inhibitory receptor?

KIR

• interacts with HLA-C

Ly49