ICS - Immunology Flashcards

1
Q

What does a haemocytoblast differentiate into?

A

Common myeloid and common lymphoid progenitors.

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2
Q

What does a common myeloid progenitor differentiate into?

A

Mast cells, megakaryocyte, erythrocytes and myeloblast.

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3
Q

What do myeloblasts differentiate into?

A

Eosinophil, basophil, neutrophil and monocytes.

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4
Q

What do monocytes differentiate into?

A

Macrophages.

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5
Q

What do common lymphoid progenitors differentiate into?

A

Natural killer cells and lymphocytes.

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6
Q

What do lymphocytes differentiate into?

A

T cells and B cells.

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7
Q

What do B cells differentiate into?

A

Plasma cells which produce antibodies.

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8
Q

What is the function of the bone marrow?

A

Where all cells originate and where B cells mature.

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9
Q

What is the function of the thymus?

A

Where T cells mature and thymic tolerance.

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10
Q

What is the function of lymph nodes?

A

Where T and B cells accumulate.

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11
Q

What is the function of the spleen?

A

RBCs are recycled here.

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12
Q

What causes large, rubbery lymph nodes?

A

Lymphomas.

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13
Q

What is innate immunity?

A

Non-specific defence system you’re born with.

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14
Q

What are the features of innate immunity?

A

Non-specific, rapid, always active and no memory.

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15
Q

What part of the innate immune system usually kill pathogens?

A

Neutrophils, macrophages and the complement system.

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16
Q

What are the barriers involved in innate immunity?

A

Physical - skin, mucus, cilia.
Chemical - lysozymes, stomach acid.

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17
Q

What is the complement system?

A

Part of innate immunity. Enhances the ability to destroy foreign antigens made up of plasma proteins that opsonise (tag) pathogens.

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18
Q

What are the pathways of the complement system?

A

C3 pathways - direct lysis, leukocyte attraction, coat invading organism.

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19
Q

Which six cells are involved in innate immunity?

A

Neutrophils, macrophages, eosinophils, basophils, mast cells and natural killer cells.

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20
Q

What are neutrophils and how many make up all WBCs?

A

Innate WBCs that make up 70% of WBCs.

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21
Q

What are macrophages? How long do they live for?

A

Innate WBCs involved in phagocytosis. Live for months to years.

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22
Q

What are eosinophils?

A

Innate WBC involved in parasitic infections.

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23
Q

What are basophils?

A

Circulating innate WBCs involved in allergy.

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24
Q

What are mast cells?

A

Innate WBCs that are fixed in tissues and involved in allergy and anaphylaxis.
IgE binding - degranulation -> histamine. T1 hypersensitivity.

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25
Q

What are natural killer cells? Which pathogens do they kill and how?

A

Innate WBCs that kill virus infected cells.
When activated they degranulate and release perforin (perforates viral infected cells).

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26
Q

How do innate immune cells recognise pathogens?

A

By TLRs. These are expressed in dendritic cells and macrophages.

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27
Q

What do TLRs respond to and why?

A

Pathogens and damage (PAMPs and DAMPs).
-Activate immune response.

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28
Q

What are the types of TLRs? What does TLR5 recognise?

A

2-9.
TLR5 - Flagella

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29
Q

What is the interface between innate and adaptive immunity?

A

The antigen-presenting cell (APC).

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30
Q

What is the function of the antigen-presenting cell?

A

They present foreign antigens to T helper cells which proliferates T helper cells and activates the B cells (humoral response).

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31
Q

What is adaptive immunity?

A

Acquired defence system to destroy and prevent the growth of pathogens (by usually antibodies).

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32
Q

What are the features of adaptive immunity?

A

Specific, slow, requires activation and has memory.

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33
Q

How does the adaptive immune system usually kill pathogens?

A

By antibodies.

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34
Q

Which cells are involved in adaptive immunity?

A

T and B lymphocytes.

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35
Q

Where do T cells mature?

A

In the thymus.

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36
Q

What are the types of T cell?

A

T helper cells, cytotoxic T cells and T memory cells.

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37
Q

What do T helper cells express and what does this do?

A

CD4 - Interact with MHC 2 and activates B cells and cytotoxic T cells.

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38
Q

What do cytotoxic T cells express and what does this do?

A

CD8 - Interact with MHC 1 and release perforin which lyses cells.

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39
Q

What are the two types of T helper cells and what do they do?

A

TH1 - Activate NK cells and macrophages (increased innate response).
TH2 - Activates B cells to differentiate into plasma cells (increased adaptive response).

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40
Q

Where are B cells produced and matured?

A

In the bone marrow.

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41
Q

How are B cells activated and why is this important?

A

TH2 cells activated (APC and MHC2). TH2 cells release:

IL4 - Induces B cell proliferation (clonal expansion)
IL5 - Induces B cell differentiation into plasma cells.

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42
Q

What are antibodies and what do they do?

A

Molecules produced by differentiated plasma cells that neutralise toxins, opsonise pathogens and destroy pathogens.

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43
Q

What are the types of antibodies?

A

GAMED Ig’s (IgG, IgA, IgM, IgE, IgD).

44
Q

Describe IgG (three things).

A

Most abundant Ig in blood.
Key in secondary immune response.
Can cross placenta.

45
Q

Describe IgA. Where is to found? What shape does it form?

A

Most abundant Ig in total body.
Found on mucosal linings and breast milk.
Forms dimer.

46
Q

Describe IgM. What does it activate? What shape do they form?

A

First Ig released in adaptive response.
Activates the complement.
Pentamer.

47
Q

Describe IgE.

A

IgE activates mast cell and basophilic degranulation type 1 hypersensitivity (anaphylaxis).

48
Q

Describe IgD.

A

Not important, function is not understood.

49
Q

What are MHCs?

A

Major histocompatibility complexes (HLA molecules).

50
Q

What is hypersensitivity?

A

Exaggerated or inappropriate immunological responses occurring in response to an antigen or allergen.

51
Q

What are the types of hypersensitivity reactions?

A

Type 1 - Anaphylaxis - IgE
Type 2 - Antigen-antibody complex
Type 3 - Immune complex deposition
Type 4 - T-cell mediated

52
Q

Explain the type 1 hypersensitivity reaction and give an example.

A

Anaphylaxis - IgE. IgE binds to basophilic mast cells, degranulates and releases histamine. E.g. atopy

53
Q

Explain the type 2 hypersensitivity reaction and give an example.

A

IgG/IgM binds to antigen and activates complement at AA site binding. E.g. Goodpastures.

54
Q

Explain type 3 hypersensitivity reaction and give an example.

A

IgG/IgA binds to antigen at site of AA deposition. E.g. SLE

55
Q

Explain type 4 hypersensitivity reaction and give two examples.

A

TH1 activated by APCs - response. E.g. TB, MS.

56
Q

What is anaphylaxis and its consequences?

A

Type 1 hypersensitivity - IgE. May present with anaphylactic shock (hypotension, tachycardia, pale, puffed).

57
Q

What are the treatments for anaphylaxis?

A

ABCDE (airway, breathing, circulation, disability, exposure).
Treat with 0.5mg IM adrenaline.

58
Q

What is immunodeficiency?

A

When the immune system’s ability to fight disease and cancer is compromised or absent.

59
Q

What are the types of immunodeficiency?

A

Acquired and inherited.

Inherited - T cell defects, IgA deficiency.
Acquired - HIV, chemotherapy.

60
Q

What are the five features of immunodeficiency?

A
  1. Decreased CD4 in HIV.
  2. B cells may be deficient (less plasma cells, less antibodies).
  3. Neutrophil and macrophage deficiency.
  4. Complement deficiency.
  5. Hyposplenism.
61
Q

What are vaccinations?

A

A form of artificial active immunity that trigger an immune response to mimic the natural infection without being symptomatic.

62
Q

What types of vaccines are there? Give examples.

A
  1. Live attenuated - MMR
  2. Antigens
  3. Toxins - Tetanus
  4. Recombinant vaccines - Hep B
  5. mRNA - Covid-19 vaccines
63
Q

What are the types of immunity?

A

Active (natural/artificial)
Passive (natural/artificial)

64
Q

Describe active immunity. Give examples of natural and artificial.

A

Ig production, secondary response, immunological memory.

-Natural; Pathogens, produce memory cells.
-Artificial; Vaccine mimics encountering pathogen and stimulates Ig production.

65
Q

Describe passive immunity. Give an example of natural and artficial.

A

Ig’s passed to host, no memory, primary response.

-Natural; Maternal Igs passed to baby in breast milk.
-Artificial; Antivenom - injection of Ig’s from another organism.

66
Q

What is immune tolerance?

A

A system to prevent faulty T/B cell response. Unresponsiveness of immune response to substances/tissues that would elicit an immune response.

67
Q

What are the types of immune tolerance?

A

Central tolerance (thymic).
Peripheral tolerance (lymph nodes).

68
Q

What is autoimmunity?

A

A pathological response to self.

69
Q

What are the types of autoimmunity?

A

Organ specific - T1DM (pancreas beta cells), MS (oligodendrocytes).
Non-organ specific - RBCs (autoimmune haemolytic anaemia), rheumatoid arthritis.

70
Q

What are cytokines?

A

Proteins secreted by immune and non-immune cells.

71
Q

What are the five types of cytokines?

A

IFs, ILs, colony stimulating factors, TNFs, chemokines.

72
Q

What is the function of interferons (IFN)?

A

They induce a state of antiviral resistance to uninfected cells.

73
Q

What are the types of interferons (IFN) and what releases them?

A

IFN alpha and beta - Produced by virus infected cells
IFN gamma - Released by activated T cells

74
Q

What is the function of interleukins (ILs)?

A

Cytokines that are either pro-inflammatory or anti-inflammatory.
Can cause cells to divide, to differentiate and to secrete factors.

75
Q

What does tumour necrosis factor do (TNF)?

A

Mediate inflammation and cytotoxic infections.

76
Q

What is the function of chemokines?

A

Leukocyte chemoattractants.

77
Q

Is the complement system continuously active?

A

No, has to be activated.

78
Q

What is the C3b pathway in the complement system?

A

Opsonisation - Tag foreign pathogens to be eliminated by phagocytes.

79
Q

What are the C3a and C5a pathways of the complement system?

A

Chemotaxes - Attracting phagocytes.

80
Q

Which proteins are involved in direct lysis in the complement system?

A

MAC (membrane attack complex).
C5b, C6, C7, C8, C9.

81
Q

What are the three main function of specific antibodies?

A
  1. Neutralise toxins by binding.
  2. Increase opsonisation (phagocytosis after).
  3. Activate complement.
82
Q

What shape is an IgM antibody?

A

Pentamer.

83
Q

What shape is an IgA antibody?

A

Dimer.

84
Q

Which cells are MHC 1 located on?

A

All cells.

85
Q

Which cells are MHC II located on?

A

Only antigen presenting cells (APC).

86
Q

How long do neutrophils live for?

A

Hours to days.

87
Q

Which receptor do neutrophils express?

A

CD66.

88
Q

What is a major function of neutrophils?

A

Mediating acute inflammation.

89
Q

How do neutrophils kill pathogens?

A

By releasing ROS.

90
Q

What are the types of macrophages?

A

Circulatory of resident (monocytes).

91
Q

What are examples of resident monocytes?

A

Kupffer cells in liver.
Alveolar macrophages in lungs.

92
Q

What do macrophages clear?

A

Apoptotic debris.

93
Q

What two things do macrophages have on their cell membrane?

A

TLRs and complement receptors.

94
Q

How do basophils lead to hypersensitivity?

A

IgE binding → Degranulation → Histamine. T1 hypersensitivity.

95
Q

Compare basophils and mast cells.

A

Both involved in allergy and hypersensitivity.
Basophils circulated whereas mast cells are fixed in tissues.

96
Q

Which cells mostly act as antigen-presenting cells?

A

Dendritic cells.

97
Q

What are two other less common examples of antigen presenting cells?

A

Macrophages and B cells.

98
Q

What is thymic tolerance and what are the two steps?

A

When T cells go to mature in the thymus.
-Positive selection and negative selection.

99
Q

What is positive selection is thymic tolerance?

A

The T cells are tested if they recognise MHCs (I and II).
-If they do, they will be either CD4 or CD8 cells.
-If they don’t they die by apoptosis.

100
Q

What is negative selection in thymic tolerance?

A

To test if T cells bind to self-antigens and produce an immune response.
-If they don’t they mature into CD4/CD8 cells.
-If they bind, they die by apoptosis.

101
Q

What is the function of MHCs?

A

To interact with T cells:
-CD4 - Interact with MHCII on APCs.
-CD8 - Interact with MHCI on all nucleated cells.

102
Q

How are MHCs involved in autoimmune disease?

A

Mutations in them can give susceptibility to autoimmune diseases.
-T1DM, coeliacs, SLE.

103
Q

Which antibody mediates T1 hypersensitivity?

A

IgE.

104
Q

Which antibodies mediate T2 hypersensitivity?

A

IgG, IgM.

105
Q

Which antibodies mediate T3 hypersensitivty?

A

IgG, IgA.

106
Q

What mediates T4 hypersensitivity?

A

T cells.