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Principles - Immunology > Immunology 2 - Late Innate Immune Responses > Flashcards

Immunology 2 - Late Innate Immune Responses Flashcards

1
Q

What are PRRs found on the cell surface for detection of?

A

Extracellular pathogens

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2
Q

What are PRRs found in the cytosol for detection of?

A

Intracellular pathogens

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3
Q

What is another name for an immune cell?

A

Leukocyte

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4
Q

Where are low levels of inactive complement system found normally?

A

Extracellular fluids

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5
Q

When the complement system is activated, what are promoted by the cascade of chemical reactions that are created?

A

Opsonisation of pathogens
Direct pathogen killing
Acute inflammation
Leukocyte recruitment

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6
Q

What are the three pathways in the complement system?

A

Classical pathway
Mannose-binding lectin pathway
Alternative pathway

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7
Q

What is C3 converted to?

A

C3a + C3b

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8
Q

What do C3a and C3b activate?

A

Downstream complement proteins

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9
Q

What is C3?

A

An acute phase protein

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10
Q

Describe the mannose-binding lectin pathway.

A

Mannose-binding Lectin binds to mannose residues on a pathogen’s surface
This activates the cleavage of C3 into C3a and b

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11
Q

Describe the alternative pathway.

A

C3b is involved in an amplification loop that converts more C3 to C3a and b

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12
Q

What is the downstream complement pathway?

A

Active C3b associates with other complement system proteins to produce C5 convertase which cleaves inactive C5 into active C5a and b
Active C5b associates with other complement system proteins to produce a pore-forming channel which inserts into the pathogen membrane (cell wall) called the MAC

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13
Q

What does MAC stand for?

A

Membrane Attack Complex

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14
Q

What enters the pathogen through the MAC and what does this cause?

A

Extracellular salts and water enter, causing the pathogen to swell and burst

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15
Q

What does opsonisation lead to?

A

Pathogen phagocytosis and killing

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16
Q

What are opsonins?

A

Soluble factors that bind to pathogens and enhance phagocytosis

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17
Q

What do C3a and C5a do?

A

Activate mast cells

Act directly on local blood vessels

18
Q

What happens if C3b binds to a human cell?

A

Active C3b associates with other complement system proteins to produce C5 convertase which cleaves inactive C5 into active C5a and b
An inhibitory protein on the surface of the human cell prevents MAC

19
Q

What are the local physiological signs of acute inflammation caused by?

A

TNF alpha
Histamine
C3a and C5a

20
Q

What are the characteristics of healthy tissue?

A

No inflammatory mediators
Normal vasculature
Circulating neutrophils

21
Q

What changes to vasculature does inflammation promote

A

Vascular changes like vasodilation and increased permeability
Recruitment and activation of neutrophils - transendothelial migration

22
Q

What is transendothelial migration?

A

The movement of substances across the endothelium into or out of the cell

23
Q

What are the steps of transendothelial migration?

A

Neutrophils move to the side of the endothelium near sites of tissue damage
Neutrophils bind to adhesion molecules on endothelial cells
Neutrophils migrate across the endothelium
Neutrophils move within the tissues via chemotaxis
Neutrophils are activated by PAMPs and TNF alpha

24
Q

What are the three killing mechanisms of neutrophils?

A

Phagocytosis
Degranulation
NETs

25
Q

What is ROS-dependent killing?

A

A second way of killing internalised pathogens

26
Q

Which are more effective at killing, macrophages or neutrophils, and why?

A

Neutrophils because they have two ways of killing internal pathogens: phagocytosis and ROS-dependent mechanism

27
Q

What is degranulation?

A

Neutrophils release anti-bacterial proteins from neutrophil granules directly into the extracellular milieu

28
Q

What is the effect of degranulation?

A

Direct killing of extracellular pathogens bacteria and fungi

Tissue damage and potentially systemic inflammation

29
Q

What does NET stand for?

A

Neutrophil Extracellular Trap

30
Q

What are NETs?

A

Neutrophils induce apoptosis in order to trap and kill pathogens

31
Q

What solves the problem of neutrophils causing bystander tissue damage?

A

Macrophages secrete wound healing anti-inflammatories

32
Q

What is the acute phase response?

A

A systematic response that involves changes in the plasma concentrations of specific proteins in response to inflammation

33
Q

What is the acute phase response driven by?

A

Pro-inflammatory mediators released by activated macrophages

34
Q

What is the acute phase response mediated by?

A

Liver hepatocytes which produce a variety of acute phase proteins

35
Q

What are examples of acute phase proteins?

A

C3
Mannose-binding Lectin (MBL)
C reactive protein (CRP)

36
Q

What does C reactive protein do?

A

Primes certain bacteria for destruction by the complement system
Has a prognostic role - severity and duration of inflammation

37
Q

What do virally-infected cells produce and release?

A

Small proteins called interferons

38
Q

How do viruses survive?

A

Invading the cells of its host

39
Q

What do interferons play a role in?

A

Immune protection against viruses

40
Q

How do interferons play a role in immune protection against viruses?

A

Prevent replication of viruses
Signal to cells to produce anti-viral factors
Warn nearby molecules of a viral presence so T cells can identify and eliminate a viral infection

41
Q

What do NK cells do?

A

Recognise and destroy virally-infected cells and abnormal cancer tissues

42
Q

How do NK cells destroy virally infected cells?

A

Release cytotoxic molecules that cause abnormal cells to undergo apoptosis
Secrete pro-inflammatory mediators

Principles - Immunology (4 decks)

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