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Immunity and Infection > The Innate Imune Response > Flashcards

The Innate Imune Response Flashcards

1
Q

What are the X2 types of immune response?

A

The innate and the adaptive/acquired

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2
Q

What branch of immune response does inflammation come under?

A

The innate immune response

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3
Q

Is the innate immune response specific or non-specific?

A

Non-specific, it is the same every time.

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4
Q

How quickly does the innate immune response take to act?

A

It is instant, minutes to hours (96hrs = 4 days)

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5
Q

When do we acquire the mechanisms to mount an innate immune response?

A

We have them from birth.

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6
Q

What is true of the way the innate immune response responds?

A

It responds the same way every time and has no memory.

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7
Q

How are the innate and adaptive immune response linked?

A

The innate immune response triggers the adaptive immune response, without one the other would not happen.

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8
Q

What are the X4 goals/stages of the innate immune response?

A

1) stop pathogen entry into the body
2) recognition of the pathogen
3) initiate various effector mechanisms for dealing with the pathogens
4) trigger the adaptive immune response

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9
Q

How does the body prevent pathogens entering the body?

A

Via openings to the body in contact with the outside world (skin, GI tract, respiratory tract.

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10
Q

What specific bacteria is found everywhere and is dealt with by the skins own antibacterial which it produces?

A

E-coli = dealt with by the skin producing PSORIASIN

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11
Q

What feature do respiratory tract cells have in defence to pathogen entry to the body?

A

They have:

1) very tight tight junctions
2) cilia to move pathogens out of the tract
3) mucous is produced to trap pathogens

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12
Q

What does the GI tract do to inhibit pathogens?

A

It uses peristalsis to ingest them and then utilises the strong acidic pH of the stomach and various enzymes to destroy the pathogens.

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13
Q

Name a mechanical and secreted product which inhibit pathogen entry to the body.

A

Blinking and tears containing LYSOZYME (destroys bacteria cell walls).

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14
Q

What internal protection do we have against pathogens that can be found in the gut and skin and how do they work?

A

We have non-harmful bacteria which compete for light/space/nutrients.

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15
Q

How does the innate immune system recognise antigens?

A

They recognise generic PAMPS (pattern associated molecular patterns) which are highly conserved and present in manny different organisms.

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16
Q

What X2 features must a molecular structure have to be considered a PAMP?

A

1) it must be found in the antigen but NOT in the host cells.
2) it must be essential for the antigens survival (therefore ensuring it will not mutate or change).

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17
Q

Name a PAMP for gram-ve bacteria?

A

The lipopolysaccharides and lipoproteins found on their outer membrane overlying the peptiodglycan cell wall.

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18
Q

Name a PAMP for gram+ve bacteria?

A

The techoic acids found in their peptidoglycan cell wall layer.

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19
Q

What feature found in the host recognises PAMP molecules?

A

PRR’s (pattern recognition receptors)

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20
Q

What does the binding of a PAMP to a PRR initiate?

A

A signal up-regulating molecules important in the immune response in the host cell nucleus.

21
Q

Name X3 types of PRR and where they are located?

A

1) Collectins = found free in plasma
2) toll-like receptors = found in the surface and intracellular membrane of cells
3) nod-like receptors = found in the cells cytoplasm

22
Q

What are collectins made from?

Give an example of a collectin.

A

1) collagen
2) lectins

E.g. mannose binding lectin

23
Q

What stops mannose binding lectin from acting on host cell mannose?

A

It only recognises mannose and fructose on antigen cells as they have a specific spacing.

24
Q

What does TLR3 recognise?

A

DsRNA

25
Q

What does TLR5 recognise?

A

Flagellin, a protein found in flagella.

26
Q

What does TLR9 recognise?

A

In-methylated DNA.

27
Q

What does TLR2 recognise?

A

Gram+ve bacteria

28
Q

What does TLR4 recognise?

A

Gram-ve bacteria

29
Q

Name the X4 effector mechanisms of the innate immune response.

A

1) the activation of complement
2) phagocytosis and killing
3) cytokines
4) activation of the adaptive immune response

30
Q

What is complement?

A

A series of circulating proteins in the blood and tissues which activate each other in a cascade.

31
Q

How many pathways are there in the complement cascade?

What do they all lead to?

A

X3 pathways exist, they are:

1) classical
2) alternative
3) MBL (mannose binding lectin)

They all lead to the cleaving of protein C3 into C3a and C3b by C3 covertase. It also activates the terminal components of the complement cascade.

32
Q

What does C3a do?

A

Diffuses away from the site of infection and binds to C3a receptors on neutrophils and macrophages to recruit them to the site of infection.

33
Q

What does C3 do?

A

It covers the surface of the antigen in a process called OPSONISATION in an attempt to make it more recognisable to the host’s phagocytic cells (macrophages and neutrophils).

34
Q

What do the terminal components of complement do?

A

They assemble to form a MAC (membrane attack complex) which is a pore which inserts into bacterial cell walls and causes lysis.

35
Q

Which leukocytes are phagocytic?

A

Macrophages and neutrophils.

36
Q

What are X3 methods of bacterial killing during phagocytosis?

A

1) lysosomal enzyme degradation
2) O2 respiratory burst
3) reactive nitrogen intermediates

37
Q

How does O2 respiratory burst work?

A

When phagocytosis occurs there is an increased O2 demand.

This O2 is reduced by NADPH oxidase, an enzyme which is part in the phagocytic cell membrane and part in the cytoplasm. The increase O2 causes these to combine.

Once they combine as a complex they convert O2 to O2 radicals which damage bacterial DNA.

38
Q

How are reactive nitrogen intermediates formed?

What enzyme catalyses this process?

A

O2 combines with L-arginine to form NO and citrulline.

This reaction is catalysed by inductively NO synthase (iNOS or NOS2).

39
Q

What induces iNOS?

A

Cytokines

= interferon gamma (IFNg)
= tumour necrosis factor (TNF)

40
Q

What are cytokines?

A

Molecules release by the immune system cells to exert an effect on other immune system cells.

41
Q

Do cytokines activate or inactivate innate immune system cells?

A

Tend to activate

42
Q

Do cytokines activate or inactivate innate adaptive system cells?

A

Tend to inactivate and ‘turn off’ inflammation.

43
Q

What specific residues are found in cytokines?

A

Cysteine.

44
Q

Which cytokine is also a chemokine and is produced by macrophages and endothelial cells to recruit neutrophils to the site of infection?

A

Interleukin 8 (IL8)

45
Q

What are the X2 types of interferon cytokines?

A

Type 1 = IF alpha and beta = these tend to activate NK (natural killer) cells

and

Type 2 = IF gamma

46
Q

What X2 signals are needed from the innate immune system to activate the adaptive immune system?

A

1) phagocytic cells which are antigen presenting cells (NOT NEUTROPHILS!) need to present small pieces of the bacteria on their surface in conjunction with MHC (major histocompatability complex).
2) a co-stimulatory signal must also be displayed. Once TLR (toll like receptors) on the antigen presenting cells recognise a PAMP with their PRR they send signals to the antigen presenting cells nucleus to display this co-stimulatory signal.

47
Q

What happens when the X2 signals are received to activate the adaptive immune system?

A

It converts naïve T-cells into effector T-cells.

48
Q

Which cells act as antigen presenting cells?

A

Dendritic cells

Macrophages

B-cells

NB: NOT NEUTROPHILS!

Immunity and Infection (6 decks)

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