Introduction and Phagocytosis. Flashcards

1
Q

What are the 2 categories of immune cells within the innate immune system?

A

Sentinel cells.

Phagocytic cells.

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2
Q

What is the function of the sentinel cells of the innate immune system?

A

They are involved in finding out what the problem is and then alerting the body to that problem.

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3
Q

What happens in the innate immune system once sentinel cells have alerted the immune system that there is a foreign substance in the body?

A

Phagocytic cells go and remove the thing that is causing the problem.

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4
Q

What are the 3 types of sentinel cells that are found in the innate immune system?

A

Macrophages (MO).

Dendritic cells (DC).

Mast cells.

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5
Q

What are the 3 phagocytic cells in the innate immune system?

A

Macrophages.

Sometime dendritic cells.

Neutrophils.

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6
Q

Are natural killer cells part of the innate or adaptive immune system?

A

The innate immune system.

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7
Q

What is the function of sentinel cells?

A

To recognise foreign invaders and warn the rest of the immune system.

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8
Q

What is the primary activators of the innate immune system?

A

The sentinel cells.

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9
Q

The sentinel cells of the innate immune system tend to be in highest concentration at what areas of the body?

A

At the site of infection or injury.

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10
Q

What cell are involved in detecting parasites or foreign microbes in the tissues?

A

The sentinel cells.

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11
Q

What allows the cells of the innate immune system to recognise pathogens?

A

Pathogen recognition receptors (PRR) on the external surface of these cells.

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12
Q

What part of a pathogen is recognised by the PRR of an innate immune cell?

A

PAMPs (pathogen associated molecular patterns) which are found on the external surfaces of microbes.

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13
Q

What allows cells of the innate immune system to recognise infected host cells?

A

DAMPs (damage associated molecular patterns).

These are cellular molecules that should be inside a cell, their presence out of the cell indicates damage.

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14
Q

Will an innate immune cell express every type of PRR?

A

No, they express different PRRs.

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15
Q

What is the major function of mast cells?

A

They are highly involved in allergy responses and can also trigger inflammation.

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16
Q

What is the major function of macrophages?

A

To capture and kill microbes and present antigens from pathogenic cells.

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17
Q

What cells of the innate immune system can be considered to be sentinel and phagocytic cells?

A

Macrophages.

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18
Q

What is the major producing antigen cell of the innate immune system?

A

Dendritic cells.

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19
Q

Can dendritic cells carry out phagocytosis?

A

Yes.

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20
Q

Will macrophages and dendritic capture antigens and present them to cells of the adaptive immune system?

A

Yes.

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21
Q

What cells are often responsible for initiating the first reaction of the adaptive immune system?

A

Dendritic cells and macrophages.

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22
Q

When are innate immune molecules made?

A

When sentinel cells are activated.

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23
Q

What are the 3 functions of innate immune molecules?

A

As pro inflammatory markers.

As inhibitors of microbial growth.

As recruiters of other components of the immune system.

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24
Q

What are cytokines?

A

Small protein molecules that are secreted by immune cells.

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25
Q

Are cytokines always present in the blood?

A

Yes.

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26
Q

Will cytokines be released by innate or acquired immune cells?

A

They can be released by both the innate immune system and the adaptive immune system.

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27
Q

What are the 3 major functions of cytokines?

A

Regulation of interactions between cells.

They impact the behaviour of cells.

Regulation of the growth and differentiation of cells.

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28
Q

What are the 4 major types of cytokine?

A

Interleukins.

Lymphokines.

Interferons.

Chemokines.

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29
Q

Are the functions of different classes of cytokines highly restricted?

A

No, all of the categories overlap meaning that a cytokine that is a lymphokine can also act as an interferon.

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30
Q

What cytokine is in highest concentration in the blood?

A

Interleukins.

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31
Q

What is the function of interleukins?

A

They control the growth and differentiation factors of cells in the immune system.

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32
Q

What immune cells secrete lymphocytes?

A

Lymphokines.

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33
Q

What are the roles of chemokines?

A

They are pro-inflammatory and chemotactic.

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34
Q

What is the role of interferons?

A

They affect viral replication and also play a role in regulating immune responses.

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35
Q

What are the 3 ways that all cytokines will act in?

A

An autocrine manner.

An endocrine manner.

A paracrine manner.

36
Q

Are cytokines only involved in local immune interactions?

A

No, they are responsible for local interactions, intermediate interactions and long distance interactions.

37
Q

The 3 most important cytokines are released by what type of cells?

A

Sentinel cells.

38
Q

What are the 3 most important cytokines that are released by sentinel cells?

A

TNF (tumour necrosis factor).

IL-1 (interleukin 1).

IL-6 (interleukin 6).

39
Q

What is the role of the 3 cytokines that are released by sentinel cells?

A

They are responsible for the initial responses to inflammation and they also regulate fever.

40
Q

Are the cytokines TNF, IL-1 and -L-6 pro-inflammatory cytokines?

A

Yes.

E.g. During a bacterial infection, once the bacteria have been recognised a macrophage will release all 3 of these cytokines.

41
Q

What are the 3 main pro-inflammatory effects of releasing TNF, IL-1 and IL-6?

A

Increased vascular permeability.

Increased blood flow.

Attraction of neutrophils to the injury/infection site.

42
Q

What are the 2 main phagocytic cells?

A

Neutrophils.

Macrophages.

43
Q

What are monocytes?

A

Derivatives of macrophages that are always found in the blood.

44
Q

Where do monocytes carry out phagocytosis?

A

In the blood.

45
Q

Where do macrophages carry out phagocytosis?

A

In the tissues.

46
Q

Are dendritic cells phagocytic?

A

Yes, but they phagocytose to present antigens rather than to kill a pathogen.

47
Q

What are the 5 soluble defence factors that are involved in phagocytosis?

A

Enzymes.

Defensins.

Interferons.

Cytokines.

Complement proteins.

48
Q

How do enzymes help with phagocytosis?

A

They cause oxidative damage to cell membranes.

49
Q

How do defensins help with phagocytosis?

A

They contain anti-bacterial peptides.

50
Q

How do interferons help with phagocytosis?

A

They can interfere with viral replication.

51
Q

What cells produce interferons?

A

Phagocytes and other cells.

52
Q

What cells produce compliment proteins?

A

Macrophages and hepatocytes.

53
Q

What are the 3 main tasks of compliment proteins?

A

Cell lysis.

Chemotaxis.

Opsonins.

54
Q

How do complement proteins kill foreign cells or infected cells?

A

Via cell lysis.

55
Q

How do complement attract other pro-inflammatory cells to areas of infection?

A

They use chemotaxis to form a chemical gradient which attracts other inflammatory cells to the site of infection.

56
Q

Can complement proteins perform opsonistation?

A

Yes.

57
Q

How do complement proteins perform opsonisation?

A

They coat microbes in molecules called opsonins which mark these microbes for phagocytosis.

58
Q

What receptors are found on most phagocytic cells?

A

PRR receptors.

59
Q

How do PRR receptors help with phagocytosis?

A

They bind to PAMPs on the microbes.

60
Q

Are intergrins found on the surface of phagocytic cells?

A

Yes.

61
Q

What is the role of the intergrins on the surface of phagocytic cells?

A

They allow neutrophils to attach to the endothelium at the area of infection.

62
Q

How do neutrophils attach to the endothelium at the site of infection?

A

Once they reach the site of infection they will use their intergrin to attach to the endothelium.

63
Q

What are leukocyte adhesion molecules?

A

A class of intergrin that are present on almost every leukocyte.

64
Q

What are the 4 main steps of phagocytosis?

A

Chemotaxis.

Adherence.

Ingestion.

Destruction.

65
Q

What is chemotaxis?

A

The directed movement of cells down a chemical gradient.

66
Q

What are 3 things that usually form a chemical gradient?

A

Microbial protein molecules.

Complement proteins.

Chemokines.

67
Q

What do chemotactic gradients help immune cells to do?

A

To get to an area of inflammation.

68
Q

What is the most common chemotactic gradient?

A

IL-8.

69
Q

Innate immune cells have receptors for what 2 soluble proteins?

A

Complement proteins.

Antibodies.

70
Q

What part of the antibody will innate immune cells bind to?

A

The FC region.

71
Q

What are opsonins?

A

Soluble proteins that are used to coat pathogens so they can be recognised by a phagocytic cell.

72
Q

Neutrophils and monocytes have receptors for what 4 things?

A

Soluble proteins.

Complement proteins.

The FC part of an antibody.

PAMPs on microbes.

73
Q

What part of a microbe will complement proteins bind to?

A

To antigens on their cell surface.

74
Q

Why do complement proteins bind to immune cells?

A

So other immune cells can recognise the microbe so it can be destroyed.

75
Q

What region of an antibody binds to the pathogen?

A

The FAB region.

76
Q

How do antibodies lead to pathogen destruction?

A

They use their FAB region to bind to pathogens.

Immune cells bind to the FC region and destroy the cell.

77
Q

Will antibodies bind to pathogens that the body has never seen before?

A

No.

78
Q

How do immune cells bind to pathogens that the body has never seen before?

A

They must bind to PAMPs.

79
Q

Can complement proteins bind to pathogens that the body has never seen before?

A

Yes.

80
Q

What happens once a phagocyte has ingested a foreign cell?

A

It is destroyed.

81
Q

What are the 2 ways that phagocytes kill ingested cells?

A

Oxygen dependent killing.

Oxygen independent killing.

82
Q

What organelles mainly carry out oxygen dependent killing?

A

The lysosomes.

83
Q

What usually carries out oxygen independent killing?

A

Substances with a very low pH, proteases, DNAse’s and RNAse’s.

84
Q

Can some pathogens survive inside a phagosome?

A

Yes.

85
Q

What are 5 common pathogens that can live inside a phagosome?

A

Mycobacterium bovis.

Rhodococcus equi.

Brucella abortis.

Lysteria monocytogenes.

Salmonella typherium.

86
Q

What is the phagosome?

A

The complex that is formed when a pathogen is ingested by a phagocyte.