Lecture 03: Inflammatory Response Overview [MCQ 1

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Questions and Answers

Which of the following cell types is NOT a resident immune cell, waiting in tissues before an infection or injury?

  • Macrophages
  • Neutrophils (correct)
  • Dendritic cells
  • Mast cells

Which of the following is NOT a primary function of mast cells in the inflammatory response?

  • Increase capillary permeability
  • Phagocytose pathogens (correct)
  • Release histamine and cytokines
  • Contribute to vasodilation

What is the primary mechanism by which neutrophils are recruited to the site of infection or injury?

  • Active transport by the lymphatic system
  • Passive transport through the blood stream
  • Chemotaxis in response to chemokines (correct)
  • Random movement and diffusion

During the inflammatory response, what is the primary effect of the release of histamine by mast cells?

<p>Vasodilation and increased capillary permeability (C)</p> Signup and view all the answers

Which of the following best describes the role of chemokines in the inflammatory response?

<p>Attract immune cells to the site of injury (A)</p> Signup and view all the answers

Which of the following is NOT a cardinal sign of inflammation?

<p>Numbness (A)</p> Signup and view all the answers

Which of the following statements accurately describes the relationship between innate immune cells and adaptive immune cells in the inflammatory response?

<p>Innate immune cells initiate the inflammatory response, and adaptive immune cells provide a more specific and long-lasting response. (A)</p> Signup and view all the answers

Which of the following accurately describes the process of extravasation during the inflammatory response?

<p>The movement of immune cells from the blood into the tissues (C)</p> Signup and view all the answers

What is the primary mechanism by which the inflammatory response is triggered?

<p>Recognition of pathogen-associated molecular patterns (PAMPS) by pattern recognition receptors (PRRs) (B)</p> Signup and view all the answers

Which of the following is NOT a key difference between acute and chronic inflammation?

<p>Type of pathogen involved (D)</p> Signup and view all the answers

Which of the following is NOT a primary function of chemokines?

<p>Directly triggering the production of proinflammatory cytokines like TNF? (D)</p> Signup and view all the answers

Which of the following statements accurately describes the relationship between chemokines and integrins during leukocyte migration?

<p>Integrins initially bind weakly to ICAMs, but their high affinity is induced by chemokines. (A)</p> Signup and view all the answers

Which of the following is NOT considered a feature of inflammatory mediators like cytokines?

<p>They are typically large proteins that require specific receptors on target cells. (C)</p> Signup and view all the answers

What is the primary role of IL-8 (CXCL8) in the inflammatory response?

<p>It acts as a chemoattractant, recruiting neutrophils to sites of infection. (B)</p> Signup and view all the answers

Which of the following accurately describes the role of integrins in leukocyte diapedesis?

<p>Integrins are involved in the firm adhesion of leukocytes to the endothelium, preparing them for diapedesis. (C)</p> Signup and view all the answers

What is the main difference between CC and CXC chemokines in terms of their target cells?

<p>CC chemokines primarily attract monocytes and macrophages, while CXC chemokines attract neutrophils. (A)</p> Signup and view all the answers

Which of the following accurately describes the role of chemokines in creating a concentration gradient during leukocyte migration?

<p>Chemokines are released in higher concentrations at the site of inflammation, creating a gradient that attracts leukocytes. (C)</p> Signup and view all the answers

Which of the following is NOT a characteristic of TNF (Tumor Necrosis Factor)?

<p>TNF is a type of cytokine that primarily functions as a chemoattractant for neutrophils. (A)</p> Signup and view all the answers

What is the main difference between the signaling mechanisms of cytokines and chemokines?

<p>Cytokines primarily influence gene expression, while chemokines are primarily involved in altering cell movement and adhesion. (D)</p> Signup and view all the answers

Which of the following events is NOT a key step in the inflammatory response orchestrated by cytokines?

<p>Direct activation of T lymphocytes to produce antibodies that target invading pathogens. (B)</p> Signup and view all the answers

Flashcards

Activation

The process where cytokines trigger endothelial cells to express ICAMs.

Chemokines

Signaling proteins that induce leukocytes to express high affinity integrins.

Diapedesis

The process of leukocytes crossing through broken endothelial junctions into tissues.

Cytokines

Proteins that mediate communication between cells, affecting adhesion and survival.

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IL-1

A proinflammatory cytokine released by macrophages and epithelial cells.

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TNF

A proinflammatory cytokine released by macrophages and neutrophils that binds to TNF receptors.

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IL-8

A chemokine that recruits and activates neutrophils during infections.

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Phagocytosis

The process by which leukocytes engulf and clear pathogens or dead cells.

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CXC and CC Chemokines

Types of chemokines that attract different immune cells: CXC attracts neutrophils and CC attracts monocytes/macrophages.

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Leukocyte Adhesiveness

The ability of leukocytes to firmly adhere to endothelial cells during the immune response.

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Inflammatory Response

A complex response to infection, involving redness, heat, swelling, and pain.

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Cardinal Signs of Inflammation

Redness, swelling, pain, and heat observed during inflammation.

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Neutrophils

Most abundant white blood cells, first responders to infection, dying after about 8 hours.

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Macrophages

Resident cells that are the first to encounter microbes, involved in phagocytosis.

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Dendritic Cells

Tissue-resident cells that sense danger and release cytokines to activate the immune response.

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Mast Cells

Cells in skin and mucosal tissues that release histamine and cytokines in response to allergens.

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Cytokine Release

The process by which immune cells release signaling molecules to communicate during inflammation.

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Vasodilation

Widening of blood vessels during inflammation to increase blood flow and immune cell access.

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Extravasation

The process where immune cells exit blood vessels to reach the injury site.

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TNF and IL-8

Types of cytokines involved in inflammation, promoting immune response.

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Study Notes

Inflammatory Response Overview

  • The inflammatory response is a cascade of events at the site of infection or injury.
  • Cardinal signs: Redness, edema, pain, and heat.
  • Acute inflammation: Short-term response to infection.
  • Chronic inflammation: Long-term response to cell damage (e.g., IBS, arthritis).

Inflammatory Cells

  • Neutrophils: Most abundant, short-lived (8 hours), phagocytic, circulate in the blood.
  • Macrophages: Resident cells, first to encounter microbes, phagocytic, found in tissues (e.g., gastrointestinal tract, skin, alveoli).
  • Dendritic cells: Resident in tissues, sense danger, release cytokines.
  • Mast cells: Resident in skin and mucosal tissues, activated by PAMPs, cytokines, or antibodies, release histamine and cytokines (causing vasodilation, increased capillary permeability, and inflammation).

Inflammatory Response Steps

  • Before infection/injury: Monocytes and neutrophils circulate, resident macrophages, dendritic cells, and mast cells reside in tissues.
  • Injury/infection: Local tissue damage, pain, bacterial entry activate immune cells.
  • Innate immune cell activation: Activation via PRRs/PAMPs.
  • Cytokine release: Release of cytokines, chemokines, histamine, and bioactive lipids (TNF, IL-8, IL-1) from damaged cells.

Capillary Alterations

  • Vasodilation: Mast cells release histamine in response to tissue damage, widening capillaries and venules.
  • Increased capillary permeability: Cytokines cause capillaries to become leaky, resulting in edema.
  • Increased blood volume and slowed flow: Allows inflammatory mediators to enter tissues.

Extravasation (Leukocyte Recruitment)

  • Rolling: Neutrophils weakly adhere to activated endothelial cells via selectins.
  • Activation: Cytokines (TNF, IL-1) trigger endothelial cells to express ICAMs and chemokines activate integrins on leukocytes.
  • Arrest: Strong adhesion of leukocytes to endothelial cells.
  • Diapedesis: Leukocytes move through endothelial gaps into tissues.
  • Chemotaxis: Chemokines attract leukocytes to the site of infection.

Phagocytosis and Wound Clearance

  • Neutrophils: Initial response.
  • Macrophages: Provide ongoing protection.
  • Dendritic cells: Travel to lymph nodes to present antigens.

Inflammatory Mediators: Cytokines

  • Cytokine function: Change cell adhesiveness, enzyme activity, regulate cell survival/death, and alter gene expression.
  • Communication steps: Stimulus, cytokine gene activation, secretion, receptor binding, signal transduction, biological effects.

Cytokine Families

  • Interleukins (ILs): Have diverse effects.

    • IL-1: Released by macrophages/epithelial cells; pro-inflammatory, binds to IL-1 receptor.
    • TNF: Released by macrophages/neutrophils; pro-inflammatory, binds to TNF receptor (important signal for apoptosis).
    • IL-8 (CXCL8): Recruits & activates neutrophils.

  • Chemokines: Chemoattractants, affect cell movement.

    • CC chemokines: Attract monocytes & macrophages.
    • CXC chemokines: Attract neutrophils (e.g., CXCL8).

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