CHP 2: Innate Immunity

Question 1

What are the three primary defense mechanisms of the innate immune system?

Answer 1

1) Physical barriers
2) Chemical barriers
3) Cells

Question 2

What is purpose have having physical barriers?

Answer 2

To prevent infection and colonization

Question 3

What is the purpose of chemical barriers?

Answer 3

To kill or inhibit microbial growth

Question 4

What is the purpose of our innates cell function?

Answer 4

To recognize and destoy pathogens via phagocytosis

Question 5

What events occur in our immune system during the first four hours after being exposed to a pathogen?

Answer 5

1) Physical and chemical barriers to prevent entry
2) Recruitment of innate immune system cells such as macrophages, neutrophils, and dendretic cells for phagocytosis

Question 6

What are opsonins?

Answer 6

Extracellular molecules that tag bacteria or viruses to be destroyed or phagocytized by our immune system

Question 7

Define PAMP

Answer 7

Pathogen associated molecule patterns: they are molecular patterns found on the surface of pathogens, these molecules are not associated with mammalian cells therefore play a key role in recognition of pathogens for our innate immunity

Question 8

What is a phagolysosome?

Answer 8

Phagosome fusion with lysosome

Question 9

What is the function of a phagolysosome?

Answer 9

create a low pH environment with digestive enzymes to destroy and degrade pathogens

Question 10

What are the five steps of phagocytosis?

Answer 10

1) Recognition of pathogen via cell receptors
2) Clustering of receptors upon pathogen binding causing invagination of the phagocyte membrane
3) Internalization of pathogen via vesicle known as phagosome
4) Fusion of phagosome and lysosomes to form phagolysosome
5) Destruction and degradation of pathogen

Question 11

Which receptors are responsible for recognizing PAMPs?

Answer 11

Pattern recognition receptors (PRRs)

Question 12

Which molecules are characterized by a broad range of microbes and not normally present in the body?

Answer 12

Pathogen associated molecules patterns (PAMPs)

Question 13

What are the types of innate immune cell receptors?

Answer 13

1) Toll-like receptors (TLRs)
2) Lectin receptors
3) Scavenger receptors
4) Cytosolic innate receptors
5) Opsonin receptors

Question 14

Where can TLR be found?

Answer 14

Phagocyte cellular membranes and endosome membrane of these cells

Question 15

Why do we have TLRs present our endosomes membranes?

Answer 15

To recognize intracellular pathogens such as viruses

Question 16

Lectin receptors play a major role in which type of anti-pathogen immunity?

Answer 16

anti-fungal immunity

Question 17

Lectin receptors bind to _______________.

Answer 17

Carbohydrates such as polysaccharides

Question 18

Which receptor plays a role in cell adhesion?

Answer 18

Lectin receptors

Question 19

Toll-like receptors are able to recognize which PAMPs?

Answer 19

1) Lipopolysaccharides (G-)
2) Lipoteichoic acid (G+)
3) Single and Double stranded RNA viruses
4) Bacterial proteins such as – flagellin, pilin

Question 20

Define cytokines

Answer 20

Secreted proteins that have signaling roles in the immune response

Question 21

Cytokines TNF-alpha and IL-1 are responsible for initiating which immune response?

Answer 21

Inflammation

Question 22

Which cytokines are responsible for initiating an inflammatory immune response?

Answer 22

TNF-alpha and IL-1

Question 23

Which type of cytokine is responsible for attracting immune cells to site of infection and inflammation ?

Answer 23

Chemokines

Question 24

Give three examples of an antiviral cytokine

Answer 24

1) IL-12
2) interferon alpha
3) interferon beta

Question 25

Which type of cytokine activates natural killer cells to find virus-infected cells and destroy them?

Answer 25

Antiviral cytokines such as interferons

Question 26

T/F: Scavenger receptor and Lectin binding activate phagocytosis

Answer 26

True

Question 27

Which cytosolic innate receptor recognizes viral RNA?

Answer 27

RIG-1

Question 28

Which cytosolic innate receptor recognizes bacterial cell wall components in the cytosol?

Answer 28

NOD-like

Question 29

Cytosolic innate receptors result in which cell responses?

Answer 29

1) inhibition of intracellular growth 2) recruitment of white blood cells such as NK cells

Question 30

When does cell signaling occur?

Answer 30

receptor clustering to a pathogen triggers intracellular signaling pathways

Question 31

What does cell signaling cause?

Answer 31

Changes in gene expression to produce and secrete cytokines

Question 32

What antiviral proteins are activated by interferons?

Answer 32

1) Protein kinase R -- inhibits protein synthesis 2) Induces RNAse L -- destruction of all RNA within the cell 3) Induces P53 -- triggering apoptosis

Question 33

T/F: TLR's are transmembrane proteins

Answer 33

True

Question 34

Ligand binding by TLRs activate ______________ factors via signaling pathways

Answer 34

Transcription

Question 35

TLRs that recognize ______________ PAMPS activate the transcription factor _________ resulting in ____________ and __________ expression

Answer 35

Bacterial; NFkB; phagocytosis; cytokine

Question 36

TLRs that recognize intracellular nucleic acids activate transcription factors _________ and ________ via _____________ ____________.

Answer 36

IRF3 and IRF7; signaling pathway

Question 37

Transcription factors IRF3 and IRF7 result in the production of?

Answer 37

Interferons and other pro-inflammatory cytokines

Question 38

What inflammatory cytokines are produced by macrophages?

Answer 38

1) IL1 and TNF- alpha 2) IL-6 3) CXCL8 4) IL-12

Question 39

The release of IL-1 and TNF-alpha results in?

Answer 39

increase in vascular permeability and induces fever

Question 40

Which cytokines induce fever and increase vascular permeability?

Answer 40

IL-1 and TNF-alpha

Question 41

What is the function of cytokine IL-6?

Answer 41

Induce fever and release acute phase proteins

Question 42

CXCL8 is a ________ that attracts which innate immune cells?

Answer 42

chemokine; neutrophils and basophils

Question 43

What is the function of IL-12?

Answer 43

Recruit and activate NK cells

Question 44

What process do neutrophils use to exit the bloodstream?

Answer 44

Extravasation

Question 45

What are the steps of extravasation?

Answer 45

1) Rolling adhesions via weak interactions between neutrophils and endothelial cells 2) Tight binding to LFA-1 and ICAM1 in response to chemokine CXCL8 3) Diapedesis: neutrophils cross the endothelial cell layer

Question 46

Which two forms do neutrophils use to attack pathogens?

Answer 46

1) Respiratory burst (use of phagosome and expose pathogen to superoxide radicals) 2) NETS - trapping of pathogens with extracellular fibers of DNA and granules

Question 47

How do our immune cells recognize infected cells versus healthy cells?

Answer 47

1) inhibitory responses -- presents peptide fragments from inside the cell 2) Activating receptors -- receptors on target cells that are in cellular stress to be destroyed or phagocytized.

Question 48

How do NK cells recruit cytotoxic T cells?

Answer 48

Via cytokines such as IFN-gamma