Innate Cells Population: NK Cells

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Questions and Answers

What function do perforin and granzyme serve in natural killer cells?

To create pores and induce apoptosis in target cells (correct)

To enhance cytokine production

To activate inflammatory responses

To promote cell adhesion

Where do natural killer cells originate from?

Granulocytic progenitor

Erythroid progenitor

Lymphoid progenitor (correct)

Myeloid progenitor

What is the role of inhibitory receptors on NK cells?

To switch off activating receptors (correct)

To enhance the killing activity of NK cells

To promote cell division

To facilitate granzyme release

How do activating receptors initiate their function in NK cells?

Through phosphorylation cascades involving kinases Signup and view all the answers

In a physiological state without intruder pathogens, which type of receptor predominates in NK cells?

Inhibitory receptors Signup and view all the answers

What is necessary for the binding of receptors to function in NK cells?

Presence of specific ligands Signup and view all the answers

Which process do phosphatases contribute to in NK cells?

Switching off signaling pathways of kinases Signup and view all the answers

Which mechanism ensures NK cells do not attack the body's own cells?

Dominance of inhibitory receptors Signup and view all the answers

What is the primary function of MHC class I molecules in relation to NK cells?

To provide inhibitory signals to NK cells Signup and view all the answers

Which ligands are typically exposed on cells when they are undergoing metabolic stress?

MICA and MICB Signup and view all the answers

What role do cytokines produced by macrophages or dendritic cells play in NK cell function?

They enhance the activation and proliferation of NK cells Signup and view all the answers

Which cytokine is considered the major important factor for maintaining and proliferating NK cells?

IL15 Signup and view all the answers

What is a distinguishing feature of HLA molecules compared to MHC class I molecules?

HLA molecules are considered a subtype of MHC class I Signup and view all the answers

What occurs when MHC class I molecules are absent on target cells?

Activating receptor signals become dominant Signup and view all the answers

Which cells typically do not express MHC class I molecules?

Erythrocytes Signup and view all the answers

What might be a consequence of fetal cells expressing different HLA from the mother?

Potential triggering of an inflammatory response Signup and view all the answers

Which type of receptors are primarily responsible for recognizing pathogens and damaged molecules on immune cells?

Pattern Recognition Receptors (PRRs) Signup and view all the answers

What is the primary function of scavenger receptors on immune cells?

Mediate the recognition of lipidic molecules typical of damaged cells Signup and view all the answers

Which type of receptor is predominantly involved in the recognition of pathogen-associated molecular patterns (PAMPs)?

Toll Like Receptors (TLRs) Signup and view all the answers

What happens after an immune cell recognizes a pathogen via its receptors?

The cytoskeleton of the phagocytic cell is activated, leading to phagosome formation. Signup and view all the answers

Which receptors are known to modulate the immune response based on sexual hormones?

Hormone receptors Signup and view all the answers

How do C-type lectin receptors contribute to the immune response?

They recognize sugars on microbes, playing a role in pathogen recognition. Signup and view all the answers

Which receptors are classified as being able to recognize both PAMPs and DAMPs?

Toll Like Receptors (TLRs) Signup and view all the answers

What role do adhesion molecules play in the behavior of immune cells?

They enable immune cells to extravasate and adhere to tissues. Signup and view all the answers

What is the consequence of a missense mutation in the IRAK gene?

Presence of a truncated form of IRAK Signup and view all the answers

Which of the following best describes the role of TLR in immune response?

To recognize molecular patterns and initiate cytokine production Signup and view all the answers

What role do TH1 and NK cells play in the immune response?

They produce IFN-γ which activates macrophages Signup and view all the answers

What is the primary effect of TLR activation on dendritic cells?

It aids in their maturation and antigen presentation Signup and view all the answers

How do macrophages respond upon activation by TLR signaling?

They enhance oxidative bursts and lytic activity Signup and view all the answers

What is the final outcome of TLR signaling in terms of immune cell interaction?

It recruits and activates NK and T cells for a stronger response Signup and view all the answers

What is the effect of cytokines produced by activated macrophages?

They facilitate the immigration of NK and T cells Signup and view all the answers

What type of immune response is primarily induced by TLR activation?

Interferon type 1 production and increased MHC expression Signup and view all the answers

What is the primary function of Mx1 protein in the immune response?

Inhibits the proliferation and replication of genetic viral material Signup and view all the answers

Which statement accurately describes the role of cytokines in the immune system?

They serve as alarm signals by activating the immune response. Signup and view all the answers

What distinguishes chemokines from cytokines?

Chemokines mediate the process of chemoattraction. Signup and view all the answers

What type of receptors do most cytokines bind to?

Both inducible and constitutive receptors Signup and view all the answers

How do HLA antigens facilitate communication in the immune system?

By binding to the T Cell Receptor (TCR) to enable cell communication Signup and view all the answers

Which hormones are mentioned as regulators of immune cell activity?

Corticosteroids, adrenaline, and noradrenaline Signup and view all the answers

Which of the following is true about membrane ligands in the immune system?

They contribute to the full activation of lymphocytes when expressed. Signup and view all the answers

What best describes the relationship between cytokines and their receptor binding?

Cytokines typically initiate their function upon receptor binding. Signup and view all the answers

Which function do cytokines NOT perform related to the immune response?

Repair tissue damage post-infection Signup and view all the answers

How do tumor necrosis factors primarily affect tumor cells?

By disrupting the blood vessels supplying the tumors Signup and view all the answers

Which statement about Transforming Growth Factors is correct?

TGF-β is an anti-inflammatory cytokine released by suppressive cells. Signup and view all the answers

What is the primary purpose of Colony Stimulating Factors (CSFs)?

Induce differentiation of hematopoietic stem cells into various immune cell precursors Signup and view all the answers

Which type of cytokines is immediately released after the recognition of a pathogen?

Tumor necrosis factor alpha (TNF-α) Signup and view all the answers

What can happen if cytokines fail to bind their specific receptors?

General activation of too many lymphoid cells could damage tissue. Signup and view all the answers

Which of the following cytokines is categorized under the interferon family?

INF-α Signup and view all the answers

Why must caution be applied when performing a Western Blot (WB) for cytokines?

Cytokines are soluble and may escape detection due to their small size. Signup and view all the answers

Study Notes

Innate Cells Population Part 2: Natural Killer Cells

NK cells, also known as Natural Killer cells, are responsible for killing cells.
NK cells contain granules, including perforin and granzyme.
Perforin creates pores in target cell membranes.
Granzyme is a protease that activates other proteases, triggering apoptosis.
NK cells originate from lymphoid progenitors, similar to lymphocytes.
They have a similar appearance to cytotoxic lymphocytes, also possessing granules.
NK cells require inhibitory receptors to prevent self-attack.
Inhibitory receptors interact with ligands (e.g., MHC class I molecules) to deactivate the cell.
Activating receptors, in the absence of inhibitory signals, trigger NK cell killing functions.
This balance between activating and inhibitory signals maintains NK cell activity.
MHC class I molecules are found on most nucleated cells.
The absence of MHC class I molecules on a target cell can lead to NK cell activation.

Education of NK Cells in the Bone Marrow

NK cells are born with both activating and inhibitory receptors in the bone marrow.
Inhibitory receptors are more prevalent during normal, healthy conditions.
Activating receptors trigger killing functions when inhibitory signaling is absent.
The resulting balance controls NK cell function.
NK cells circulate in the blood and tissues.
Inhibitory signaling normally prevails since MHC class I molecules are present.
The absence of MHC class I or presence of activating signals triggers NK cell activation.

Antibody-Dependent Cellular Cytotoxicity (ADCC)

ADCC is an NK cell process that uses antibodies to target cells for destruction.
NK cells possess CD16 receptors that recognize antibody constant regions.
Antibody binding to target cells activates NK cell degranulation.
NK cells are important players in ADCC, but macrophages also participate.
ADCC kills infected cells by antibody-mediated activation of NK cells.
Activating receptors on NK cells (e.g., CD16) have ITAM motifs (Intracellular Tyrosine Activating Motifs).
Inhibitory receptors on NK cells (e.g., KIRs) have ITIM motifs (Intracellular Tyrosine Inhibitory Motifs).

Cytokines that Activate NK Cells

Cytokines regulate NK cell activity.
IL-15 is important for NK cell proliferation and maintenance.
Other cytokines influence various NK cell functions.
Cytokines are produced by macrophages, dendritic cells, or helper lymphocytes.

Innate Lymphoid Cells (ILCs)

ILCs are lymphocytes similar to lymphocytes in their origin.
ILCs do not express membrane receptors for antigen (TCR).
ILCs comprise 3 groups (ILC1, ILC2, and ILC3) based on their cytokine production.
ILCs differentiate in response to cytokines and microenvironments.
ILCs activate other immune cells to respond to damage or infection at specific sites.

Microbial Signals and ILC Subsets

Microbial signals activate various ILC subsets.
ILC1, 2, and 3 subsets have varying roles in responses to different microbial or tissue damage signals
ILCs are crucial for inflammatory responses and tissue repair.

Cytosolic Receptors

Cytosolic receptors are intracellular proteins recognizing pathogen components.
NLRs (NOD-like receptors) detect bacterial components and trigger inflammasome formation.
RLRs (RIG-like receptors) recognize viral RNA.
CDSs (cytosolic DNA sensors) identify intracellular bacteria and viruses' DNA, initiating immune responses.

Toll-Like Receptors (TLRs)

TLRs are membrane receptors recognizing pathogen-associated molecular patterns (PAMPs) of pathogens or cells.
TLRs initiate signal cascades leading to immune responses.
TLR activation leads to a cascade of intracellular events, ultimately leading to immune responses.
There are many TLRs, each with varying specificities for particular microbial elements.
There may be multiple receptors working together.

Danger Signals: The Alarmins

Alarmins are molecules signaling cellular stress or damage.
They can activate innate immune responses.
Important examples include ATP, heat shock proteins, and mitochondrial DNA.
These molecules participate in the inflammatory response to tissue damage and cellular stress.

Clinical Case: Douglas Mooster

The case study highlights the role of Toll-like receptors (TLRs) in immunity.
Douglas has inadequate TNF production.
Defective intracellular pathways or receptor deficiency could account for a lack of adequate immune responses.
An essential step in diagnostics is evaluating gene expression.
This leads to impaired inflammasome activation and Toll-like receptor signaling, affecting his cellular responses to infections.

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Description

This quiz covers the essential functions and mechanisms of Natural Killer (NK) cells, including their role in destroying target cells through perforin and granzyme. Learn about the balance of activating and inhibitory signals that regulate NK cell activity and their relation to MHC class I molecules. Test your knowledge on the origin and characteristics of these vital immune cells.