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A Haematology and Immunology > Introduction to Immunology > Flashcards

Introduction to Immunology Flashcards

1
Q

What are the 3 components of immunity?

A

-Physical barriers -Innate immunity -Adaptive immunity

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2
Q

What physical barriers are there?

A

-Skin and epithelial mucosa -Secretions -Gastric acid -Normal flora -Physiological -Physical flushing of urinary tract

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3
Q

What secretions provide a barrier to infection?

A

-Sweat -Tears -Gastric acid -Sebaceous glands -Mucous -Breast milk

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4
Q

What are the protective components of saliva?

A

-Lysozyme: digests proteoglycan in bacterial walls -IgA: prevents attachment of microbes and may neutralise microbes insitu -IgG -Lactoferrin: sequesters free iron and has direct antimicrobial effects

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5
Q

How can commensal bacteria prevent infection?

A

-Compete for nutrients -Prevent attachment -Release fatty acids and antibacterial proteins -Prevent invasion

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6
Q

What do lactobacilli in the vagina do?

A

Cause acidic pH (4-4.5)

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7
Q

What physiological responses prevent infection?

A

-Temperature (fever) -pH -Location of immune cells within the bloodstream

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8
Q

Give examples of conditions where there is breached defences to infection.

A

-Burns, xerostomia -Cystic fibrosis -C. difficile

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9
Q

Why can burns lead to infection?

A

Allow pathogens access and more optimal growing conditions

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10
Q

Why can CF lead to infection?

A

Increased viscosity of mucous reduces the ability of the cilia to clear infections allowing damage to the lungs to occur

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11
Q

Why can C.diff lead to infection?

A

Increase in bacteria due to abnormal flora which can lead to toxic megacolon

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12
Q

What cells are involved in the innate immune system?

A

-Mast cells -NK cells -Basophils -Neutrophils -Eosinophils -Monocytes -Macrophages -Dendritic cells

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13
Q

What molecules are involved in the innate immune system?

A

-Complement -Interferon -Cytokines -Acute phase reactants

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14
Q

What receptors are involved in the innate immune system?

A

Pattern recognition receptors -Toll like receptors -Mannan-binding lectin

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15
Q

What molecules are involved in the adaptive immune system?

A

-Immunoglobulins -Cytokines

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16
Q

What cells are involved in the adaptive immune system?

A

-T cells -B cells

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17
Q

What receptors are involved in the adaptive immune system?

A

-T cell receptors -B cell receptors -MHC/HLA

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18
Q

What are the mechanisms of the innate immune system?

A

-Inflammation -Recruitment of immune cells -Activation of complement -Opsonisation -Phagocytosis (and endocytosis) -NK cytotoxicity

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19
Q

What are the features of the innate immune system?

A

-First line of defence -Rapid -Already present at birth -Some specificity -No memory – same response with re-exposure -Detects alteration from haemostasis

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20
Q

What do cytokines do?

A

-Regulate the nature, duration and intensity of the immune response -Form a method of ‘communication’ between components of the immune system -Bind to specific receptors on target cells

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21
Q

What produces cytokines?

A

Predominantly macrophages and T cells

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22
Q

Give examples of pro-inflammatory cytokines.

A

-TNF-a -IL-1 -IL-6 -Chemokines

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23
Q

What is involved in the inflammatory response?

A

-Fever -Vasodilation -Recruit and activate other immune cells -Increase glucocorticoids leading to stress hyperglycaemia (also decrease in inflammatory response)

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24
Q

Give examples of anti-inflammatory cytokines.

A

-IL-10 -TGF-B

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25
Q

What cytokines activate macrophages?

A

IFN-y

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26
Q

What cytokines activate eosinophils and mast cells?

A

-IL-3 -IL-4 -IL-5 -IL-13

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27
Q

What cytokines activate B cells?

A

-IL-4 -IL-5 -IL-6 -IL-21

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28
Q

What cytokines activate T cells?

A

-IL-2 -IL-4 -IL-12 -IFN-y

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29
Q

What cytokines act on bone marrow to increase leukocyte production?

A

-Gm-CSF -IL-3

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30
Q

What is inflammation a result of?

A

-Detection of foreign/breach in defences by pattern recognition receptors

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31
Q

What causes vasodilation?

A

-Nitric oxide -Bradykinin -Prostaglandins -TNF-a -IL-1

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32
Q

What causes increased vascular permeability?

A

-Nitric oxide -Leukotrienes -Histamine

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33
Q

What causes increased cell adhesion molecules?

A

-TNF-a -IL-1

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34
Q

What causes chemotaxis?

A

CXCL-8

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35
Q

What causes increased sensitivity to pain?

A

Bradykinin

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36
Q

What are the 3 complement pathways?

A

-Classical -Lectin -Alternative

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37
Q

What complement components are involved in chemotaxis of phagocytes to site of inflammation?

A

C3a C5a

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38
Q

What complement components are involved in opsonisation?

A

C3b C4b

39
Q

What complement components are involved in lysis of micro-organisms?

A

C5b-9 complex

40
Q

What complement components are involved in maintaining solubility of Ag/Ab complexes?

A

C3b C4b C2

41
Q

What is opsonisation?

A

Preparing for eating -Reduces repellent negative cell charge -Increases no. of binding sites for phagocytes

42
Q

What are the main opsonins?

A

-Complement C3b, C4b -Antibodies -Plasma proteins – mannose binding lectin

43
Q

Briefly describe phagocytosis.

A

-Endocytosis -Enzyme destruction of pathogen -Exocytosis of waste products -Extracellular pathogens

44
Q

When does NK cytotoxicity occur?

A

If reduced MHC I expression leads to inhibition and destruction of cell

45
Q

What are the features of the adaptive immune system?

A

-Specific -Delayed -Immunological memory -Faster responses to known antigen

46
Q

What are the divisions of the adaptive immune system?

A

Humoral -Antibody-mediated -B lymphocytes Cell-mediated -T lymphocytes

47
Q

Where do lymphocytes mature?

A

-T cells in the bone marrow and thymus -B cells in the bone marrow -B and T cells then migrate to secondary lymphoid organs, where they encounter antigen

48
Q

Antigen

A

A molecule capable of inducing an immune response

49
Q

Antibody

A

A glycoprotein produced by B lymphocytes that binds antigens with a high degrees of specificity and affinity

50
Q

How do lymphocytes with diverse antigen binding sites arise?

A

Genetic changes

51
Q

How do T cells recognise antigens?

A

Require presentation of antigen via MHC -CD4+: MHCII -CD8+: MHCI (all nucleated cells and platelets)

52
Q

How do B cells recognise antigens?

A

Recognise antigen directly

53
Q

What type of pathogens do MHCI process?

A

Intracellular

54
Q

What type of pathogens do MHCII process?

A

Extracellular

55
Q

What central tolerance do T cells undergo?

A

In the thymus -Positive selection: can T cells recognise MHC? -Negative selection: does T cell interact too strongly with self-antigens via MHC?

56
Q

What central tolerance do B cells undergo?

A

In the bone marrow -Self-reacting BCR

57
Q

What is peripheral tolerance?

A

-Monitoring of lymphocytes within secondary lymphoid organs and circulation -Regulatory T cells recognise and destroy self-reactive lymphocytes

58
Q

What do cytotoxic T cells do?

A

Release IFN-y and TNF-a -Direct anti-viral and anti-tumour effects Release cytotoxic granules: - Perforin + granzyme = apoptosis of target cell Apoptosis also via: -FasL-Fas interactions

59
Q

What is perforin induced apoptosis?

A

-MHCI binds to CD8 -Release of perforin and granzyme -perforin creates a pore in the cell membrane -Granzyme enters the cell and triggers apoptosis

60
Q

What do help T cells do?

A

-Release cytokines to ‘help’ the activity of other immune cells -Promote B cell antibody class switching e.g. IgM to IgG

61
Q

What do Th1 cells do?

A

Intracellular pathogens -Maximise macrophage and CD8+ activity -Release IFN-γ -Inhibit TH2 response

62
Q

What do Th2 cells do?

A

Extracellular pathogens -Release IL-4, IL-5, IL-13 -Activate mast cells, basophils, eosinophils -Class switching to IgE -Inhibit Th1 response

63
Q

What do Th17 cells do?

A

Extracellular pathogens -Pro-inflammatory -Recruit neutrophils and macrophages via CXCL-8

64
Q

What do regulatory T cells do?

A

-Suppress CD4+ and CD8+ T cells -Control the response to self-antigens -Secrete IL-10 and TGF-β (anti-inflammatory and suppresses immune system)

65
Q

What does the FAB region of Ig bind to?

A

Antigen

66
Q

What does the Fc region of Ig bind to?

A

Communicates with immune cells

67
Q

What Ig is best at achieving complement?

A

IgM

68
Q

What Ig can cross the placenta?

A

IgG

69
Q

What Ig is contained in secretions?

A

IgA

70
Q

What Ig is involved in parasitic infections and allergy?

A

IgE

71
Q

How does antibody mediated immunity vary with time?

A

Immunity increases with each exposure

72
Q

What are the functions of antibodies?

A

-Immune complex formation -Opsonisation -Activating the cascade complement (classical) -Antibody dependent cellular toxicity (ADCC) (bind to target cells and initiate a non-phagocytic cell-mediated destruction)

73
Q

What factor produces normal variation in immune function?

A

Age

74
Q

How does ageing affect immune function?

A

Elderly -Thymic involution -Fewer naïve T cells – dependent on memory T cells -Reduced ability for T cell expansion -Reduced B cell development and diversity (Diminished response to vaccination) -More dependent on innate immunity (But reduced function of pattern recognition receptors and superoxide killing)

75
Q

What cause secondary immune deficiency?

A

Environmental -Malnutrition, trauma, burns Disease -Infection, diabetes, renal failure, asplenia, malignancy Iatrogenic -Splenectomy, drugs

76
Q

What drugs can cause immunodeficiency?

A

-Immunosuppressant’s -Anti-rheumatics -Anti-epileptics

77
Q

Why is there immunodeficiency in HIV?

A

Virus binds to CD4+ cells to gain entry -T helper cells -Immune deficiency due to reduced CD4+ T helper cell function: - B cells, NK, CD8+, macrophage activity

78
Q

What proteins are affected in protein-calories malnutrition?

A

-Cytokines -Acute phase reactants -Chemokines

79
Q

What is deficient in zinc malnutrition?

A

-PMN -NK -Monocytes -B and T cells have impaired function

80
Q

What is deficient in iron malnutrition?

A

-Enzymes within cellular function and metabolic pathways -Impaired innate immune function

81
Q

What is zinc essential for?

A

Proliferating cells

82
Q

What is ciclosporin?

A

Calcineurin inhibitor: reduced inflammatory cytokine release from T cells-

83
Q

What does rituximab do?

A

-Binds to CD20 (B lymphocytes) -Allows NK and complement mediated apoptosis

84
Q

What do glucocorticoids do?

A

Anti-inflammatory -Activate lipocortins: reduce phospholipase A2 and arachidonic acid release -Alter transcription of enzymes needed for inflammation

85
Q

How are B cells activated by Th cells?

A

-Anigen binds to B cell via BCR -MHCII detects extracellular pathogen and binds to Th which activates B cell Leads to: -Proliferation of B cells -Production of memory B cells -Formation of plasma cells (production of free antibody specific to antigen) -Neutralisation -Opsonisation

86
Q

What triggers the classical complement pathway?

A

Immune complexes (Ab-Ag)

87
Q

What does the lectin complement pathway start with?

A

Mannose binding lectin

88
Q

What triggers the alternative complement pathway?

A

C3b directly binding to a microbe

89
Q

Can you name the differences between the innate and adaptive immune responses?

A

Innate immune response

  • rapid
  • already present at birth
  • some specifity
  • no memory - same response with re-exposure
  • detects alterations

Adaptive immune response

  • delayed
  • immature at birth
  • highly specific
  • good memory - faster response to known antigens
  • humoral and cell mediated
90
Q

How do macrophages, mast cells and dendritic cells recognise cells as foreign?

A

Pattern recognition receptors

91
Q

Functions of the innate immune system

A
  • Inflammation
  • Recruitment of immune cells
  • Activation of complement
  • Opsonisation
  • Phagocytosis
  • NK cytotoxicity
92
Q

Unfortunately, macrophages do not find it easy to kill Mtb once they have engulfed it, why?

A

Mtb has a waxy coat and secretes catalase which inhibits phagocytosis. Macrophages struggle to kill them and just seal them off in phagosomes.

93
Q

What other immune functions do macrophages and dendritic cells have?

A

Antigen presentation to T cells via MHC II and MHC I

A Haematology and Immunology (20 decks)

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