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Natural Killer Cells and Their Cytotoxic Activity

Description: This quiz is designed to assess your understanding of Natural Killer Cells and Their Cytotoxic Activity.
Number of Questions: 15
Created by:
Tags: immunology natural killer cells cytotoxicity
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What is the primary function of Natural Killer (NK) cells?

  1. Antibody production

  2. Phagocytosis

  3. Cytotoxic activity

  4. Antigen presentation


Correct Option: C
Explanation:

NK cells are specialized lymphocytes that play a crucial role in the innate immune system by directly killing infected or cancerous cells through cytotoxic mechanisms.

What type of cells are commonly targeted by NK cells?

  1. Red blood cells

  2. Neutrophils

  3. Virus-infected cells

  4. Plasma cells


Correct Option: C
Explanation:

NK cells primarily target and eliminate virus-infected cells, as well as cancerous cells, by releasing cytotoxic molecules that induce cell death.

Which receptor on NK cells recognizes and binds to ligands expressed on target cells?

  1. TCR (T cell receptor)

  2. BCR (B cell receptor)

  3. KIR (Killer cell immunoglobulin-like receptor)

  4. CD4


Correct Option: C
Explanation:

KIRs are expressed on the surface of NK cells and recognize specific ligands, known as KIR ligands, which are present on target cells. This interaction triggers NK cell activation and cytotoxicity.

What is the primary cytotoxic mechanism employed by NK cells?

  1. Antibody-mediated cytotoxicity

  2. Complement-mediated cytotoxicity

  3. Fas-mediated apoptosis

  4. Perforin and granzyme-mediated cytotoxicity


Correct Option: D
Explanation:

NK cells release perforin and granzymes, which are cytotoxic molecules that form pores in the target cell membrane, leading to cell lysis and apoptosis.

Which cytokine is primarily responsible for NK cell activation?

  1. Interferon-gamma (IFN-γ)

  2. Interleukin-2 (IL-2)

  3. Interleukin-4 (IL-4)

  4. Tumor necrosis factor-alpha (TNF-α)


Correct Option: B
Explanation:

IL-2 is a cytokine that plays a critical role in NK cell activation and proliferation. It binds to the IL-2 receptor on NK cells, triggering intracellular signaling pathways that promote cytotoxicity.

What is the role of NK cells in tumor surveillance?

  1. They suppress tumor growth

  2. They promote tumor angiogenesis

  3. They facilitate tumor metastasis

  4. They inhibit tumor cell proliferation


Correct Option: A
Explanation:

NK cells are involved in tumor surveillance by recognizing and eliminating tumor cells. They play a crucial role in preventing tumor growth and metastasis.

Which molecule is expressed on healthy cells and recognized by NK cells to prevent self-destruction?

  1. MHC class I molecules

  2. MHC class II molecules

  3. CD45

  4. CD56


Correct Option: A
Explanation:

Healthy cells express MHC class I molecules, which are recognized by inhibitory receptors on NK cells. This interaction prevents NK cells from attacking and destroying healthy cells, a process known as self-tolerance.

What is the term used to describe the ability of NK cells to distinguish between healthy and infected or cancerous cells?

  1. Immune surveillance

  2. Immune tolerance

  3. Immune memory

  4. Immune recognition


Correct Option: D
Explanation:

Immune recognition refers to the ability of NK cells to differentiate between healthy and infected or cancerous cells based on specific markers or ligands expressed on their surfaces.

Which signaling pathway is activated in NK cells upon target cell recognition?

  1. MAPK pathway

  2. PI3K pathway

  3. Jak-STAT pathway

  4. NF-κB pathway


Correct Option: B
Explanation:

The PI3K (Phosphoinositide 3-Kinase) pathway is activated in NK cells upon target cell recognition. This pathway regulates various cellular processes, including cell activation, proliferation, and cytotoxicity.

What is the role of NK cells in regulating adaptive immune responses?

  1. They suppress T cell activation

  2. They promote B cell differentiation

  3. They enhance antibody production

  4. They stimulate dendritic cell maturation


Correct Option: D
Explanation:

NK cells can stimulate the maturation and activation of dendritic cells, which are antigen-presenting cells that play a crucial role in initiating adaptive immune responses.

Which transcription factor is essential for NK cell development and function?

  1. T-bet

  2. GATA-3

  3. RORγt

  4. FoxP3


Correct Option: A
Explanation:

T-bet (T-box transcription factor expressed in T cells) is a key transcription factor that regulates NK cell development, maturation, and cytotoxic function.

What is the term used to describe the phenomenon where NK cells become anergic or hyporesponsive after prolonged exposure to target cells?

  1. NK cell exhaustion

  2. NK cell tolerance

  3. NK cell anergy

  4. NK cell senescence


Correct Option: A
Explanation:

NK cell exhaustion refers to the state of functional impairment and hyporesponsiveness that can occur in NK cells after prolonged exposure to target cells or chronic stimulation.

Which receptor on NK cells is involved in the recognition of antibody-coated target cells?

  1. FcγRIIIa (CD16)

  2. KIR (Killer cell immunoglobulin-like receptor)

  3. NKG2D (Natural cytotoxicity triggering receptor 2)

  4. CD56 (Neural cell adhesion molecule)


Correct Option: A
Explanation:

FcγRIIIa (CD16) is an activating receptor expressed on NK cells that binds to the Fc portion of antibodies bound to target cells, triggering antibody-dependent cell-mediated cytotoxicity (ADCC).

What is the role of NK cells in viral infections?

  1. They suppress viral replication

  2. They promote viral entry

  3. They enhance viral shedding

  4. They facilitate viral transmission


Correct Option: A
Explanation:

NK cells play a crucial role in controlling viral infections by recognizing and eliminating virus-infected cells, thereby suppressing viral replication and spread.

Which cytokine is produced by NK cells that can inhibit tumor growth and angiogenesis?

  1. Interferon-gamma (IFN-γ)

  2. Interleukin-4 (IL-4)

  3. Interleukin-10 (IL-10)

  4. Tumor necrosis factor-alpha (TNF-α)


Correct Option: A
Explanation:

NK cells produce Interferon-gamma (IFN-γ), a cytokine that has anti-tumor effects by inhibiting tumor cell proliferation, inducing apoptosis, and suppressing angiogenesis.

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