Innate Immune Response - Humoral Elements

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Questions and Answers

Which cytokines are known to stimulate the production of acute phase proteins by hepatocytes?

IL-10, IL-8, and TNF-a

IL-1, IL-6, and TNF-a (correct)

IL-2, IL-4, and IL-5

IL-12, IL-15, and IL-17

What is the primary function of C-Reactive Protein (CRP) in the immune response?

Inhibits inflammation and immune response

Binds to and opsonizes pathogens (correct)

Activates T-cells and B-cells

Directly kills pathogenic microbes

Which of the following contributes to the activation of the complement system?

The presence of antibodies only

Only through adaptive immune responses

Only through innate immune responses

Sequential cascade of complement proteins (correct)

Mannan Binding Lectin (MB-lectin) primarily functions as which of the following?

An opsonin for monocytes Signup and view all the answers

What role do acute-phase proteins play in the immune system?

They modulate inflammation Signup and view all the answers

What are the roles of lipid mediators in the immune response?

Increase vascular permeability and dilation Signup and view all the answers

From which acid are lipid mediators predominantly derived?

Arachidonic acid Signup and view all the answers

Which enzyme is responsible for converting arachidonic acid into prostaglandins?

Cyclooxygenase Signup and view all the answers

What is the primary function of antimicrobial peptides?

Form pores in microbial membranes Signup and view all the answers

What is the primary function of cytokines in the innate immune response?

To mediate local and systemic effects Signup and view all the answers

Which type of immune cells express all three groups of antimicrobial peptides?

Neutrophils Signup and view all the answers

Which cytokine is responsible for inducing fever and activating vascular endothelium?

IL-1 Signup and view all the answers

What do collectins and ficolins primarily recognize on pathogens?

Carbohydrate patterns Signup and view all the answers

What is the role of IL-6 in the innate immune response?

Induces class switching and production of acute phase proteins Signup and view all the answers

What is the consequence for individuals deficient in mannose binding lectin (MBL)?

Greater risk of meningococcal disease Signup and view all the answers

Which of the following is a function of interferons?

Inhibit viral replication Signup and view all the answers

Which mechanism provides protection to host cells from the effects of antimicrobial peptides?

Presence of sialic acids on surface Signup and view all the answers

Which cytokine is a major chemoattractant for neutrophils?

IL-8 Signup and view all the answers

What is the role of TNF-a in the immune response?

Activating vascular endothelium and increasing permeability Signup and view all the answers

Which cells primarily produce IFN-g?

T cells and NK cells Signup and view all the answers

What is the primary effect of the chemokine MCP-1?

Chemoattractant for monocytes Signup and view all the answers

Study Notes

Innate Immune Response - Humoral Elements

The innate response employs soluble molecules to combat pathogens
Key molecules include cytokines, chemokines, antimicrobial peptides, complement proteins, acute-phase proteins, and collectins.

Cytokines

Cytokines affect both local and systemic processes
Several cytokines are vital mediators
- IL-1 (produced by macrophages, endothelial cells, some epithelial cells) activates vascular endothelium, certain lymphocytes, increases IL-6 production and induces fever.
- IL-6 (produced by macrophages, endothelial cells, T cells) elevates antibody production and stimulates class-switching; also induces acute-phase protein production in the liver.
- TNF-α (produced by macrophages and T cells) activates vascular endothelium, increases vascular permeability, activates neutrophils, and induces fever, apoptosis, and muscle/fat catabolism (cachexia); can cause septic shock.
- IL-12 (produced by macrophages and dendritic cells) stimulates interferon-gamma (IFN-γ) from T cells and natural killer (NK) cells; drives T cell activation.

Interferons (IFNs)

IFNs are produced by various cells, including immune cells
Three types: IFN-α, IFN-β, and IFN-γ
Exhibit antiviral activities, chiefly by acting against double-stranded RNA (dsRNA).

Antimicrobial Peptides

Produced by epithelial cells and neutrophils
Typically 29-35 amino acids long
Three main groups include α-defensins, β-defensins, and cathelicidins
Neutrophils express all three types, while epithelial cells express according to location.
These peptides act directly on microbes, binding to acidic phospholipids within microbe membranes and forming pores.
Host cells are protected from these peptides by sialic acid residues on their cell surfaces.

Collectins and Ficolin

Two protein families: collectins and ficolins
Typically found in mucosal surfaces and in the blood serum.
Collectins and ficolins recognize unique carbohydrate patterns on microbes that distinguish them from host cells
Enable these proteins to identify pathogens as foreign entities.
Mannose-binding lectin (MBL) is a collectin that binds mannose residues.
Ficolins bind to N-acetylglucosamine (GlcNAc) residues.
They are key parts of the immune response, helping opsonise pathogens and activate the complement cascade.
Deficiencies in these proteins (e.g., MBL deficiency) correlate with increased risks of certain diseases (e.g., meningococcal disease).

Acute Phase Proteins (APPs)

TNF-α, IL-1, and IL-6 stimulate hepatocytes to release APPs.
Important APPs include:
- C-reactive protein (CRP) binds to phosphorylcholine on bacterial and fungal cell walls, opsonizing pathogens and activating complement.
- Mannan-binding lectin (MBL) acts as an opsonin for monocytes and activates the complement cascade.
These APPs play a role in inflammation regulation and promote pathogen clearance

Complement

A group of serum proteins that contribute to both innate and adaptive immunity.
Complement proteins enhance the functions of antibodies by 'completing' their action.
Operating through a sequential cascade of activation steps.
Activated through three main pathways:
- Classical
- Mannan-binding lectin (MBL)
- Alternative
Further detail is available in subsequent learning.

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Description

Explore the key aspects of the innate immune response, focusing on humoral elements such as cytokines and other soluble molecules. This quiz covers essential mediators like IL-1, IL-6, and TNF-α, explaining their roles in combating pathogens and regulating immune responses.