Ch2pp43-47

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Questions and Answers

Which cells are mainly recruited to the site of infection in the acute inflammatory response?

T cells and B cells

Neutrophils and monocytes (correct)

Eosinophils and basophils

Dendritic cells and macrophages

What is the main mechanism for defending against intracellular bacteria?

Complement system activation

Mast cell degranulation

Phagocytes activated by TLRs and other innate sensors (correct)

NK cells and type I IFNs

What contributes to redness, warmth, and swelling, characteristic features of acute inflammation?

Activation of T cells

Exudation of plasma proteins (correct)

Release of type I IFNs

Inhibition of mast cell degranulation

What provides protection against viruses in the innate immune system?

Type I IFNs and NK cells Signup and view all the answers

What is the main mechanism that directs leukocytes from the endothelium into tissue?

Chemokine-mediated motility Signup and view all the answers

What is the consequence of deficiencies in integrins and selectin ligands?

Leukocyte adhesion deficiencies (LADs) Signup and view all the answers

What process involves the destruction of pathogens with the help of plasma proteins like complement proteins?

Phagocytosis Signup and view all the answers

What enhances phagocytosis of microbes by neutrophils and macrophages?

Opsonization with antibodies and complement fragments Signup and view all the answers

What do phagocytes produce to kill ingested microbes?

Reactive oxygen species (ROS) and nitric oxide (NO) Signup and view all the answers

What is released by neutrophils for the destruction of microbes?

Microbicidal granule contents and neutrophil extracellular traps (NETs) Signup and view all the answers

What does an inherited deficiency of phagocyte oxidase cause?

Chronic granulomatous disease (CGD) Signup and view all the answers

What may cause tissue injury due to the release of enzymes and ROS into the extracellular space?

Inflammation Signup and view all the answers

Apart from eliminating pathogens and damaged cells, what else do cells of the immune system initiate?

Tissue repair Signup and view all the answers

Which type of leukocyte provides defense against helminthic parasites?

Eosinophils Signup and view all the answers

What are the main phagocytes involved in the inflammatory response?

Neutrophils and blood monocyte-derived macrophages Signup and view all the answers

What initiates the sequence of events in leukocyte migration into tissues?

TNF and IL-1 acting on the endothelium of venules near the site of infection Signup and view all the answers

What promotes the movement of leukocytes from the blood into the tissues?

Vascular permeability, expression of endothelial adhesion molecules, and chemokines Signup and view all the answers

What occurs in response to TNF and IL-1 during leukocyte rolling?

Venular endothelial cells express adhesion molecules of the selectin family Signup and view all the answers

What is responsible for arresting rolling leukocytes on the endothelium?

Expression of ligands for integrins by TNF and IL-1 acting on the endothelium Signup and view all the answers

What stimulates a rapid increase in the affinity of leukocyte integrins for their ligands on the endothelium?

Chemokines produced within a site of infection by tissue macrophages and other cells Signup and view all the answers

What is involved in leukocyte migration to infection sites?

Weak tethering and rolling, firm adhesion, and migration through the endothelium to the site of infection Signup and view all the answers

What is responsible for reorganizing the cytoskeleton of leukocytes as they spread out on the endothelial surface?

The firm binding of integrins to their ligands on the endothelium Signup and view all the answers

What is produced at infection sites that is involved in leukocyte migration?

Chemokines in fibrin and fibronectin Signup and view all the answers

What occurs within a site of infection that stimulates an increase in affinity of leukocyte integrins for their ligands on the endothelium?

Tissue macrophages produce chemokines Signup and view all the answers

Study Notes

Inflammatory Response and Leukocyte Migration: Key Mechanisms

Inflammatory response involves accumulation of phagocytes, mainly neutrophils and blood monocyte-derived macrophages, in tissues in response to cytokines produced by various cells such as macrophages, dendritic cells, and mast cells.
Cytokines and other mediators increase vascular permeability and expression of endothelial adhesion molecules and chemokines, promoting the movement of leukocytes from the blood into the tissues.
The acute inflammatory response involves a 7-step mechanism including injury, activation of sentinel cells, secretion of inflammatory mediators, increased vascular permeability, killing of microbes, leukocyte migration into tissue, and phagocytosis and killing of microbes.
Neutrophils and monocytes migrate to extravascular sites of infection or tissue damage by binding to venular endothelial adhesion molecules and in response to chemoattractants produced by tissue cells.
TNF and IL-1 act on the endothelium of venules near the site of infection, initiating the sequence of events in leukocyte migration into tissues.
Rolling of leukocytes occurs in response to TNF and IL-1, where venular endothelial cells express adhesion molecules of the selectin family and circulating neutrophils and monocytes express surface carbohydrates that bind specifically to the selectins.
At sites of infection, macrophages, dendritic cells, and other cells produce cytokines such as TNF and IL-1 that activate the endothelial cells of nearby venules to express selectins and ligands for integrins and to secrete chemokines.
Leukocyte migration to infection sites involves weak tethering and rolling of blood neutrophils on the endothelium, firm adhesion of neutrophils, and migration through the endothelium to the site of infection, also used by blood monocytes and activated T lymphocytes.
Leukocytes express integrins in a low-affinity state on unactivated cells, and within a site of infection, tissue macrophages and other cells produce chemokines, stimulating a rapid increase in the affinity of the leukocyte integrins for their ligands on the endothelium.
TNF and IL-1 act on the endothelium to stimulate expression of ligands for integrins, including ICAM-1 and VCAM-1, which arrest the rolling leukocytes on the endothelium.
The firm binding of integrins to their ligands arrests the rolling leukocytes on the endothelium, and the cytoskeleton of the leukocytes is reorganized as they spread out on the endothelial surface.
Leukocyte migration involves the secretion of chemokines in fibrin and fibronectin at the infection site, and macrophages stimulated by microbes produce cytokines (TNF, IL-1) and chemokines, leading to firm adhesion of leukocytes

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Description

Test your knowledge about the innate immune system and its role in eliminating microbes through acute inflammatory responses, antiviral defense mechanisms, and recruitment of immune cells such as neutrophils and monocytes. Learn about the different types of innate immune responses effective against various types of microbes.