Innate Immunity and Inflammatory Response

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Questions and Answers

What is the role of ligands VCAM and ICAM in vasodilation?

They facilitate the release of chemokine IL-8 to increase the number of innate immune cells.

They mediate the recognition and attachment of phagocytes to pathogens.

They enable rolling phagocytes to anchor on the endothelial layer. (correct)

They allow phagocytes to cross the endothelial layer into the affected site.

What is the purpose of chemokine IL-8 released by activated endothelial and PMN cells?

To promote the transendothelial migration of phagocytes.

To facilitate the firm attachment of phagocytes to the endothelial layer.

To increase the rolling of phagocytes on the endothelial layer.

To increase the number of innate immune cells gathered at the affected site. (correct)

What is the primary function of physical barriers in innate immunity?

To produce antimicrobial peptides

To activate the adaptive immune response

To produce cytokines

To prevent infection by pathogens (correct)

What is the next step after firm attachment of phagocytes to the endothelial layer?

Transendothelial migration of phagocytes into the affected site. Signup and view all the answers

Which of the following immune cells is responsible for killing tumor cells and viral infected cells?

NK cells Signup and view all the answers

Which of the following is an example of a chemical barrier?

Lysozyme in tears Signup and view all the answers

What is the primary function of cytokines in the inflammatory response?

To activate and enhance immune responses Signup and view all the answers

What is the role of cytokines in transendothelial migration?

They help phagocytes cross the endothelial layer into the affected site. Signup and view all the answers

What is the role of collectins in innate immunity?

To bind to polysaccharides on microbes Signup and view all the answers

Which of the following types of interferons is produced by lymphocytes and NK cells?

IFN-γ Signup and view all the answers

What is the purpose of phagocytosis in the inflammatory response?

To engulf and eliminate microbial cells. Signup and view all the answers

What is the function of lymphatic vessels?

To connect tissues with lymph nodes Signup and view all the answers

What is the term for the process of phagocytes crossing the endothelial layer into the affected site?

Transendothelial migration Signup and view all the answers

What is the primary role of monocytes in the immune response?

To engulf and digest pathogens and dead cells Signup and view all the answers

Which of the following is an example of autocrine signaling?

Cytokines produced and acting on the same cell Signup and view all the answers

What is the role of eosinophils in innate immunity?

To produce and release toxic agents Signup and view all the answers

What is the primary role of chemokines in the inflammatory response?

To attract and recruit immune cells to the site of infection Signup and view all the answers

Which of the following is NOT a primary lymphoid organ?

Lymph node Signup and view all the answers

What is the function of mast cells in innate immunity?

To produce histamine and heparin Signup and view all the answers

What is the mechanism by which immune cells migrate from the blood stream into infected tissues?

Rolling, activation, and transmigration Signup and view all the answers

Which of the following cytokines is involved in inducing vasodilation during the inflammatory response?

TNF-α Signup and view all the answers

What is the role of neutrophils in innate immunity?

To phagocytose small pathogens Signup and view all the answers

Which of the following is NOT a mechanism of killing and degradation?

Antigen presentation Signup and view all the answers

Which of the following is an example of an acute phase protein?

C-reactive protein (CRP) Signup and view all the answers

Which of the following is NOT a type of antigen presenting cell?

T cells Signup and view all the answers

What is the result of MHC class I presentation?

Cytotoxicity Signup and view all the answers

Which of the following is an example of a non-lysosomal dependent mechanism of killing and degradation?

Respiratory burst Signup and view all the answers

What is the result of IL-1 signaling in the brain?

Induction of fever and anorexia Signup and view all the answers

Which of the following is NOT a function of MHC class II?

Cytotoxicity Signup and view all the answers

What is the result of IL-6 signaling in the liver?

Promotion of acute phase proteins synthesis Signup and view all the answers

Study Notes

Innate Immunity

Pre-existing defense mechanism that prevents infection by pathogens
Provides immediate defense against infectious agents

First-Line Barriers to Infection

Physical Barriers

No information provided in the text

Chemical and Biochemical Barriers

Lysozyme in tears, sweat, and saliva
Fatty acids
Hydrochloric acid (HCL)
Lactic acid and propionic acid in the vagina and urinary tract

Antimicrobial Peptides in Secretions

Defensins in mucosal and skin secretions
Cathelicidins in mucosal secretions
Collectins that bind to polysaccharides on microbes

Lymphoid Organs

Primary Lymphoid Organs

Bone marrow (B cell maturation)
Thymus (T cell maturation)

Secondary Lymphoid Organs

Lymph nodes
Spleen
MALT (Payer's patch)

Lymphatic Vessels

Connect tissues with lymph nodes
Contain lymphocytes (T and B cells) and tissue dendritic cells

Spleen

Deals with antigens shed into the bloodstream

Innate Immune Cells

Mast cells: involved in hypersensitivity reactions
Basophils: produce histamine, heparin, and proteolytic enzymes in response to allergens
Eosinophils: involved in hypersensitivity reactions and parasitic infections
Neutrophils: phagocytose/engulf small pathogens
Monocytes (blood circulation) and macrophages (tissues): engulf pathogens and larger particles, present antigens on MHC class I or class II
NK cells: induce IFN-γ production (activates macrophages and cell-mediated immunity), kill tumor cells, and kill viral, intracellular pathogen, and protozoan-infected cells

Inflammatory Response

Mediated by:
- Cytokines (activation and enhance responses)
- Chemokines (attract and recruit immune cells)
- Innate immune cells (phagocytosis and inflammatory response)

Cytokines

Paracrine: released by producer and acts on neighboring cells
Autocrine: produced, released, and acts on the producer
Endocrine: released by producer into the circulation (lymphatic and blood) and acts on a distant cell

Interferons

IFN-α and IFN-β: produced by macrophages, fibroblast, endothelial, and epithelial cells; activated by viral dsRNA; antiviral effects
IFN-γ: produced by lymphocytes and NK cells; activates macrophages

Migration of Cells from Blood Stream into Infected Tissues

Rolling: IL-1 released by epithelial cells and polymorphonuclear (PMN) cells activates neighboring PMN, which release TNF-α to induce vasodilation
Activation and firm attachment (adhesion): chemokine IL-8 increases the number of innate immune cells, and phagocytes attach firmly to the endothelial layer
Transendothelial migration (extravasation/transexudation): phagocytes cross the endothelial layer into the affected site and engulf pathogens

Phagocytosis

Recognition and attachment: mediated by surface receptors on macrophages/neutrophils
Ingestion: formation of pseudopodia to engulf microbial cells, inclusion of microbes in the phagosome
Killing and degradation:
- Lysosomal dependent: chlorine products, defensins, proteolytic enzymes
- Non-lysosomal dependent: respiratory burst, oxygen radicals, NO (inhibits viral replication)
Antigen presentation: macrophages, dendritic cells, and B cells present antigens to activate cell-mediated immunity, especially T cells

The Inflammatory Response

Systemic

No information provided in the text

Local

No information provided in the text

Acute Phase Response

Cytokine and the brain: IL-1 induces fever, somnolence, and anorexia
Cytokine and the liver: IL-6 promotes acute phase proteins synthesis in the liver, e.g., fibrinogen, haptoglobulin, C3, mannose-binding protein, serum amyloid A, C-reactive protein (CRP is an inflammatory marker)

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Description

This quiz covers the components and mechanisms of innate immunity and its activation, leading to the inflammatory response. Understand the concepts and consequences of innate immunity activation. A lecture note by Yap Wei Boon, Ph.D.