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Miscellaneous > MCB Lecture 42 Innate Immune System > Flashcards

MCB Lecture 42 Innate Immune System Flashcards

0
Q

What are the two types of molecules that can be detected on microbes?

A

PAMPs: molecules conserved in microorganisms. Not unique, but rather found in many taxonomical groups eg. LSP

Antigens: molecules on a microorganism that are particular to that particular species. Eg. Haemoglutinin and Neurominadase on influenza virus

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1
Q

Why have an immune system?

A

To protect the individual against invading microorganisms

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2
Q

Which receptor recognises PAMPs?

A

PAMP recognition receptor

PRR

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3
Q

Which receptor recognises antigens?

A

Antigen receptor

Antibody

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4
Q

What are the requirements of the innate immune system? (4)

A
  1. Rapid
  2. Present at birth
  3. Appropriate for pathogen
  4. Distinguish self from non self
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5
Q

What are opportunistic infections?

A

These are microorganisms that only cause harm when given the opportunity; opportunistic invaders

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6
Q

Describe how and when the immune system evolved

A

It enveloped due to pressure from microorgansism a that were invading and causing harm

The innate immune system evolved first
The adaptive immune system evolved when some pathogens escaped the innate immune system

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7
Q

What are the characteristics of the innate immune system? (5)

A
  1. Fast response
  2. The magnitude is constant
  3. First line of defence
  4. Non specific
  5. Interacts and educated the adaptive response
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8
Q

What are the components of the innate immune system?

A

Barriers, secretions, cells

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9
Q

Describe how epithelium is part of the immune system

A 
These form a physical barrier to prevent microorganisms getting into the host
Eg. 
Epithelium of trachea and lungs
Skin epithelium
Gut epithelium
Nasal epithelium
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10
Q

Describe how secretions form part of the immune system

A

These are secreted by epithelium, and prevent microorganisms from getting in, or killing them

Eg.
Mucous secreted by trachea epithelium
Lysosyme and Phospholipase A in the mouth and tears
Gastric juice: acidic to kill the pathogen
Bile salts

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11
Q

Where is lysosyme found?

A

In the mouth and in tears

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12
Q

Where is Phospholipase A found?

What does it do?

A

In the mouth and in tears

It disrupts the cell membrane of bacteria and other pathogens

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13
Q

Describe how normal flora protect us in the immune response

A

Commensals are found on many outer surfaces of the body
They take up space so that other bacteria which are harmful cannot take up residence
They prime out innate immune system

Eg. 
On skin
In throat
In the gut
Vagina
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14
Q

What are plasma factors ? (3)

A
  1. C reactive proteins
  2. Mannose binding lectin
  3. Complement proteins
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15
Q

Describe the function of C reactive protein

A

These coat microbes and trigger phagocytosis and the complement cascade

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16
Q

What is mannose binding lectin?

A

It is a protein that binds to mannose on the surface of a bacterium.
It triggers the complement cascade

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17
Q

What is a lectin?

A

It is a protein that binds to a sugar

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18
Q

Give a brief description of the complement system

A

Activated via one of three pathways
Critical step: C3 is cleaved
Outcomes: microbe is phagocytosed, lysed and phagocytes and inflammatory cells are attracted

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19
Q

How can the complement system be activated?

A
  1. Classical pathway: antibody binds. C1 -> C2 -> C4
  2. Lectin pathway: lectin binds to mannam.
  3. Alternate pathway: binding to molecules on the surface of the pathogen
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20
Q

What is the critical step in the complement system?

A

Cleavage of the C3 protein

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21
Q

What does proteolysis of the complement proteins bring about?

A

It brings about the evolution of other cleavage products

These bind to the surface of pathogens and bring about the outcomes

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22
Q

What are the outcomes of the complement system?

A
  1. Opsonisation : C3b coats a pathogen, and phagocytosis is induced
  2. Lysis: C5,6,7,8,9 come together to form a pore in the cell wall of the microbe. The cell lyses and dies
  3. Chemotaxis: C3,4,5a attract phagocytes and inflammatory cells
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23
Q

Describe the process of opsonisation

How is it activated?

A

C3b coats a microbe, and phagocytosis is induced

It is activated by the cleavage of C3, ie the complement system

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24
Q

Describe the process of chemotaxis

How is it activated?

A

Cleavage products from c,savage of C3 attract phagocytes and inflammatory cells to the area
It is activated by the complement system

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25
Q

Describe the process of microbial lysis

How is it activated?

A

C5,6,7,8,9 come together to form a pore in the microbial cell wall
The cell lyses and dies

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26
Q

What are the three different types of cell in the innate immune system?

A

Phagocytic
Cytotoxic
Inflammatory

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27
Q

What is a neutrophil?

A

It is also known as a granulocyte

It is a phagocytic cell

28
Q

What is a Monocyte?

A

It is a precursor to a macrophage

It has phagocytic capabilities

29
Q

What is a phagocyte?

A

It is a cell that engulfs and kills a bacterium

30
Q

What is a dendritic cell?

A

It’s a phagocytic cell

31
Q

What is a Eosinophil?

A

It is a cytotoxic cell

It releases toxic granules that kill microbes

32
Q

What is a NK cell?

A

It is a cytotoxic cell

It releases toxic granules that kill microbes

33
Q

What is a basophils?

A

These are inflammatory cells

They release inflammatory substances

34
Q

What are the two lineages of cell production?

Where does this occur?

A

Myeloid: neutrophil, Monocyte, macrophage, Eosinophil, basophils
Lymphoid: NK cell, b lymphocyte, t lymphocyte

35
Q

What is the role of receptors in the innate immune system?

A

These bind to the PAMP and a signal transduction pathway is initiated
Normally, gene transcription will be altered: production of defensins etc

36
Q

What are some receptors in the innate immune system?

A

Toll like receptor (TLR)
NOD
RIG

37
Q

Describe the function of toll like receptors

A
  1. Ligand (PAMP) binds
    PAMP can be: element of the flagellum, CgP DNA, LPS
  2. Signal transduction pathway ensues
  3. Gene transcription is altered: anti-infection factors, defensins
38
Q

What are the outcomes of PRR-PAMP?

A

Phagocytosis
Expression of certain cell surface receptors
Production of chemokines, cytokines, defensins

39
Q

What are cytokines?

A

These are molecules that are released by an infected cell that tell neighbouring cells (with the correct receptor) that it is infected

40
Q

What are chemokines?

A

These are molecules released by infected cells that attract cells with the appropriate receptor to the area

41
Q

What stimulates the production of cytokines and chemokines?

A

PRR binding to a PAMP

42
Q

Which receptors detect chemokines?

What is special about these receptors?

A

CCR
CXCR

They both have two cyteines

43
Q

What a the two types of phagocytes?

A

Polymorphonuclear neutrophils

Mononuclear phagocytes

44
Q

What are the functions of phagocytes?

A

They engulf and kill pathogens

They produce and release cytokines and chemokines

45
Q

Describe the process of phagocytosis

A
  1. Extension of Filopodia
  2. Formation of a phagosome
  3. Formation of phagolysosome
  4. Lysis and killing of the bacterium
46
Q

What molecules bring about degredation and killing of microbes in the lysosome?

A 
Hydrolytic enzymes
Low pH
Reactive oxygen species
Reactive nitrogen species
Defensins
47
Q

What are the two options in the outcome of the innate immune system?

A

The pathogen is removed

The pathogen avoids removal, and the adaptive immune system must play a role

48
Q

What are the four types of cytokines?

A

Inflammatory
Antiviral
Stimulatory
Suppressive

49
Q

What is the role of IL-1?

A

This is an inflammatory cytokine released by activated macrophages

50
Q

What is the role of IL-6?

A

This is an inflammatory cytokine released by activated macrophages

51
Q

What is the role of IL-12?

A

This is a stimulatory cytokine released by activated macrophages

52
Q

What is the role of IL-10?

A

This is a suppressive cytokine released by activated macrophages

53
Q

What is the role of GM-CSF?

A

This is a stimulatory cytokine released by activated macrophages

54
Q

What is the role of TNF-alpha?

A

This is an inflammatory cytokine released by activated macrophages

55
Q

What is the role of TGF-beta in the innate immune system?

A

This is a suppressive cytokine released by activated macrophages

56
Q

What is the role of IFN-alpha?

A

This is an antiviral cytokine released by activated macrophages

57
Q

Which are the inflammatory cytokines released by activated macrophages?

A

IL-1
IL-6
TNF-alpha

58
Q

Which are the stimulatory cytokines released by macrophages?

A

GM-CSF

IL-12

59
Q

Which are the antiviral cytokines released by activated macrophages?

A

IFN-alpha

60
Q

Which are the suppressive cytokines released by activated macrophages?

A

IL-10

TGF-beta

61
Q

Which chemokine is released by activated macrophages?

A

CXCL8, aka IL-8

62
Q

What are defensins?

A

These are molecules produced by macrophages that bind to and kill bacteria that have been phagocytosed by putting holes in the bacterial cell membrane. The bacteria experiences efflux of nutrients and ions, and dies

63
Q

Which chemicals are present in tears that protect from microbes?

A

Lysozyme

Phospholipase A

64
Q

Which chemicals are present in the mouth that protect from microbes?

A

Lysozyme
Phospholipase A
Histatins

65
Q

Which chemicals are present in the stomach and gut that protect from microbes?

A

Low pH
Bile salts
A-defensins
Lysopeptide

66
Q

Which chemicals are present on the skin that protect from microbes?

A 
Fatty acids
Lysozyme
Low pH
RNA-ases
DNA-ases
67
Q

Which chemicals are present on the vagina that protect from microbes?

A

Low pH

68
Q

Which chemicals are present in the respiratory tract that protect from microbes?

A

Beta-defensins

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