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Flashcards in Hypersensitivity Deck (131):
1

what is hypersensitivity

immune mediated disease caused by inflammation & not by infection

2

what type of environment is the immune system essential

where many harmful microorganisms/pathogens are present

3

what has the immune system evolved to protect the body against

pathogens:
- viruses
- bacteria
- fungi
- parasites

4

what are immune responses mediated by

- a variety of cells
- soluble mediators that these cells produce

5

when can the immune system cause harm

- when it is absent of suppressed, so the body is open to opportunistic infections which lead to immunodeficiency i.e. an immune deficient disease such as AIDS
or
- when the immune system responds in a very aggressive way in trying to alleviate the damage that he pathogen or other antigen causes, so the immune system does harm to our bodies

6

what are the components of the immune system as mixture of

chemicals and cells

7

name the two types of leukocytes which act as components of the immune system

lymphocytes & phagocytes

8

what are the lymphocyte components of the immune system

B cell
T cell
large granular lymphocyte LGL

9

what soluble mediator do B cells produce

antibodies

10

what soluble mediator do T cells produce

cytokines

11

what soluble mediator do large granular lymphocytes produce

cytokines

12

what are large granular lymphocytes also known as, and what are they involved in

natural killer cells
involved in defence against viruses

13

what are the phagocyte components of the immune system

mononuclear phagocyte
neutrophil
eosinophil

14

what soluble mediators do mononuclear phagocytes produce

- cytokines
- complement

15

how do mononuclear phagocytes work

engulf antigens & sometimes destroy them
or
sometimes act as antigen presenting cells

16

how many % of leukocytes do neutrophils account for

70%

17

what property do neutrophils have

they are principle white cells of the blood, and also have a phagocytic property

18

where can neutrophils exist

they can exists within the blood, but can also leave blood & enter the tissues & phagocytose within the tissues

19

what are all the possible soluble mediators

- antibodies
- cytokines
- inflammatory mediators

20

what are the two granulocytes

eosinophils
basophils

21

what are the auxiliary cells - components of the immune system

basophils
mast cells
platelets

22

what do the auxiliary cells - basophils, mast cells and platelets form

inflammatory mediators

23

what are T cells responsible for

cell mediator immunity

24

what type of mechanism are phagocytes a part of

innate defence mechanism

25

how do phagocytes destroy antigens and pathogens

by internalising them, and in order to destroy the engulfed particles, phagocytes have strong enzymes which if released to tissue can damage

26

give examples of phagocytes which internalise the antigens and pathogens and destroy them

monocytes (and macrophages) and polymorphonuclear neutrophils

27

what are the body's first line of defence

barriers of our immune system within the body e.g. mucosal or skin barrier

28

what is the first defence of our body once a pathogen or antigen has passed the barriers of our immune system

phagocytes

29

what are B cells and T cells responsible for

recognition/detection of antigen

30

what are B cells/lymphocytes responsible for

antibody production

31

what do T helper cells produce

cytokines

32

what are cytokines

chemicals which regulate the immune system

33

what do type 1 T-helper cells (TH-1) cells do

activate/control macrophages

34

hat do TH-2 cells do

help B cells to divide and differentiate and make antibodies as well as produce cytokines

35

what do cytotoxic T cells (CTL or Tc) do

destroy virally infected cells and tumour cells

36

how do cytotoxic T cells (CTL or Tc) destroy virally infected cells and tumour cells

by recognising them via a mechanism and triggers a process of apoptosis and the cell dies

37

what do large granular lymphocytes (NK cells) have similar properties to and what are those properties

cytotoxic T cells
destroy virally infected cells and tumour cells

38

what do auxillary cells control

inflammation

39

what is the main purpose of inflammation

to attract leukocytes towards the site of infection

40

what is inflammation mediated by

a variety of other cells including mast cells and basophils

41

what do mast cells and basophils contain

granules

42

what do granules contain

soluble mediators of immunity

43

what are mast cells and basophils also capable of synthesising and secreting apart from soluble mediators of immunity

other mediators that control immune reactions

44

what do mast cells contain

histamine

45

what happens to blood vessels when histamine is released

dilate and become leaky

46

what is histamine

an inflammatory mediator which acts upon blood vessels

47

what are the variety of chemical mediators which are involved in the development of immune responses

- antibodies and cytokines - produced by lymphocytes
- other serum proteins e.g. complement

48

what is opsonisation

process which acts in conjunction with antibodies which facilitates phagocytosis

49

how do some complement destroy bacteria

through process of lysis

50

what is the complement system a group of

about 20 serum proteins that interact with each other and other elements of the immune system

51

list the functions of the complement system

- opsonisation of microorganisms e.g. bacteria
- attraction of phagocytes
- increased blood flow and increased vascular permeability
- damage to cell membranes
- release of mediators from mast cells

52

what does immune homeostasis require

a balance between:
- immunodeficiency (hypo-reactivity)
&
- immunopathology (hyperactivity)

53

what is immunodeficiency (hypo-reactivity) of the immune system, and give examples

suppressing of immune system which dampens down i.e. it is a poorly acting immune system e.g.
- neutrophil disorders
- antibody deficiency
- complement deficiency
- T-cell dysfunction

54

what is immunopathology (hyperactivity) of the immune system, and give examples

immune system responds in too much of an aggressive manner e.g.
- autoimmunity organ specific
- allergies and asthma
- pathogen induced pathology

55

what types of immunodeficiency can there be

- congenital - born with immunodeficient immune system
- mostly acquired, mainly through organ transplants where strong drugs suppress the immune system or by diseases such as AIDS caused by a virus

56

what are hypersensitivity reactions

exaggerated or inappropriate immune responses that lead to tissue damage, can be mild or life threatening

57

what are the four types of hypersensitivity reaction recognised by Coombs and Gel 1963

type 1
type 2
type 3
type 4

58

what type of hypersensitivity are the most common

type 1 mediated reactions

59

briefly list the type of reaction associated with each type of hypersensitivity

type 1 - immediate hypersensitivity reaction
type 2 - antibody mediated reactions
type 3 - immune complex mediated reactions
type 4 - cell mediated reactions

60

how long does it take for a type 1 hypersensitivity to occur

within minutes of exposure

61

what is another word for type 1 hypersensitivity

atopy

62

what causes type 1 hypersensitivity

exposure to a variety of environmental antigens e.g.
- pollen
- house dust mite
- animal dander
all termed allergens
- mild hay fever (strong genetic link)
- severe anaphylaxis
- allergens also contribute to asthma

63

what is the meaning of an allergen

something that causes an allergy

64

what is another word for hay fever

seasonal allergic rhinitis

65

what are hay fever sufferers allergic to

airborne pollens ans spores

66

what are the symptoms of hay fever

- sneezing
- rhinorrhoea (runny nose), nasal congestion
- itching of the nose and eyes
- watering of the eyes
- wheezing and shortness of breathing

67

when do symptoms of hay fever usually occur

between march and September

68

when is tree pollen released and how many % does it affect

from march to may - spring affects 25% of sufferers

69

when is grass pollen released and how many % does if affect

from may to late July - affects 90% of sufferers

70

when is fungal spores released

until September

71

what is the most important allergen in 'house dust'

dust mite

72

what causes the allergy from the dust mite

mite faecal pellets is what causes the allergy as they are similar size to pollen grains so give rise to similar symptoms to hay fever

73

which period do dust mites cause allergy symptoms

all year round

74

how severe is an anaphylaxis allergic reaction and what can it be caused by

very dangerous - life threatening
caused by particular foods especially nuts, insect bites or medicines

75

how many of the population does anaphylaxis affect

1-3 per 10,0000 per year (rare)

76

what are the early signs of an anaphylaxis allergic reaction

swelling and itching, the face may be flushed and wheals or hives (urticaria) bumps may erupt on the skin

77

what are the later signs of an anaphylaxis allergic reaction

- swelling of the face
- difficulty breathing and wheezing due to laryngeal oedema (mucous membrane swell & airways gets blocked) or asthma
- loss of colour, cold and clammy as blood pressure falls
- collapse/loss of consciousness

78

what is the emergency treatment for anaphylaxis

intramuscular pre loaded injection of adrenaline (epinephrine) followed by iv drip when they reach hospital of anti-histamine and corticosteroids

79

what happens when someone encounters the allergen for the first time

they have no signs and symptoms at all

80

what is type 1 hypersensitivity mediated by

mast cells

81

what do mast cells display a high affinity receptor for

IgE

82

what is IgE synthesised in response to

certain antigens (allergens)

83

when allergens are deposited on the mucous membranes, what are they taken up by

taken up and processed by antigen presenting cells (e.g. dendritic cells or B cells)

84

once the allergen is taken up by antigen presenting cells, what are they presented to

presented through an MHC receptor to TH2 cells which provide cytokine signals to (activate) B cells to produce IgE which binds to mast cells

85

what is IgE

an antibody which is unusual, so if your allergic to something, you produce IgE

86

what does cross linking of IgE by subsequent exposure to allergen (after the 2nd time) cause

calcium influx or cells and starts a mast cell degranulation

87

what receptors do mast cells have

Fc receptors

88

what is mast cell degranulation the major initiation of

the acute allergic reaction

89

name some mast cell mediators

- histamine
- heparin
and other factors

90

what do the mast cell mediators, histamine and heparin cause

- mucus secretion
- vasodilation
- oedema

91

describe the whole type 1 mechanism

- mast cells display a high affinity receptor for IgE
- IgE is synthesised in response to certain antigens (allergens)
- allergens are deposited on mucous membranes and taken up and processed by antigen presenting cells (e.g. dendritic cells or B cells)
- allergen presenting to TH2 cells which provide cytosine signals to B cells to produce IgE Ig E binds to mast cells
- cross linking of IgE by subsequent exposure to allergen causes mast cell degranulation
- mast cell degranulation is the major initiation of the acute allergic reaction
- mast cell mediators include, histamine, heparin and other factors
- these causes, mucus secretion, vasodilation and oedema

92

what two types of mediators do mast cells include

pre formed & newly formed mediators

93

name some pre formed mast cell mediators

- histamine
- heparin
- neutral protease

94

name some newly formed mediators

- leukotrienes
- prostaglandin D2
- platelet activating factor

95

what does the degranulation of the mast cell cause

the allergy

96

what is hay fever and anaphylaxis due to

the mast cell mediators

97

what is type 2 hypersensitivity mediated by

antibody mediated response/hypersensitivity

98

in type 2 hypersensitivity, what is the antibody directed against

membrane and cell surface antigens (autoantibodies) which recognise our cells as foreign

99

in type 2 hypersensitivity, what do antigen-antibody reactions activate

complement, producing membrane damage

100

in type 2 hypersensitivity mechanism, what do the antibodies bind to

the cell surface

101

in type 2 hypersensitivity mechanism, what do phagocytes bind to the antibody via and what does it cause

their Fc receptor and causes phagocytosis of target cell

102

in type 2 hypersensitivity mechanism, what does antibody binding also activate and what does this set up

complement, which sets up the inflammatory process within the tissue & automatically leads to organ destruction/cell lysis

103

explain type 2 hypersensitivity antibody mediated mechanism on a blood vessel wall

- the antibodies are recognising the epithelium that are making up the wall of the blood vessel as foreign
- so they are binding onto those endothelial cells as they think it is foreign & initiate this inflammatory reaction
- the phagocytes then come along to try to destroy this antigen
- in doing so they release the toxic enzymes and chemicals into the vicinity of the blood vessel wall
- and that produces lots of localised cell damage

104

how do anti histamines work

antihistamines bind to the histamine receptor so that the histamine has got nothing to bind onto, so it works well by blocking histamine receptors

105

describe the whole of type 2 hypersensitivity mechanism

- antibodies bind to cell surface
- phagocytes bind to the antibody via their Fc receptor
- phagocytosis of target cell
- antibody binding also activates complement which sets up the inflammatory process within the tissue
- complement mediated cell lysis/destruction

106

what occurs during haemolytic disease of the newborn

- erythrocytes from a RhD+ foetus (first child) leak into the maternal circulation (who is RhD-), usually during birth which stimulates the production of anti-Rh antibody
- during subsequent pregnancies, IgG antibodies are transferred across the placenta into the foetal (2nd child) circulation
- if the foetus is again incompatible, the antibodies cause erythrocyte (red blood cell) destruction

107

at which pregnancy does a haemolytic disease of a newborn occur

2nd or after

108

instead of carrying out a blood transfusion on a baby who has haemolytic disease, what do hospitals do in order to avoid it from happening

after the first pregnancy, they treat the mother with a drug which takes out all the anti RhD+ antibodies, so when theres a 2nd baby, the antibodies are not able to cause haemolytic disease

109

what is type 3 hypersensitivity mediated by

immune complex response mediated

110

what does type 3 hypersensitivity cause excessive formation of

immune complexes eg persistent low grade infection, repeated inhalation of antigens

111

give some examples of type 3 hypersensitivity

- farmers lung
- immune complex glomerulonephritis

112

what is farmers lung

when farmers are exposed to hay spores & hay spores form immune complexes & often happens in the lung so they end up with breathing difficulties

113

what do immune complexes activate in type 3 hypersensitivity mechanism

complement

114

what do immune complexes deposit within in type 3 hypersensitivity mechanism

tissues

115

what and where a immune complexes degraded by in type 3 hypersensitivity mechanism

phagocytes, particularly in the liver and spleen

116

what does excessive immune complex formation result in, in type 3 hypersensitivity mechanism

deposition in the tissues, particularly arterioles, kidneys and joints

117

what do immune complexes induce in type 3 hypersensitivity mechanism

platelet aggregation and complement activation

118

what does attempted phagocytosis cause in type 3 hypersensitivity mechanism

enzyme release and results in tissue damage

119

in type 3 hypersensitivity mechanism, when theres an excess of immune complexes, what occurs

the immune system overloads and the phagocytes can't cope with all those immune complexes & the immune complexes start to deposit in tissues such as lungs & kidneys which initiates this inflammatory reaction

120

what type of hypersensitivity is type 4 hypersensitivity

delayed type

121

how long does type 4 hypersensitivity take to develop after antigenic change

more than 12 hours (typically 12-48 hours)

122

give examples of type 4 hypersensitivity

- contact dermatitis = excema (coating of base metal)
- tuberculin reaction (mantoux test)

123

what type of molecules do antigens in type 4 hypersensitivity include

large or small (haptens) linked to carrier molecules

124

what other type of drug can cause a type 4 hypersensitivity

eye drops which treat an initial infection

125

in type 4 hypersensitivity mechanism, what do antigen presenting cells (APC) resident in the skin process and migrate

process antigen & migrate to regional lymph nodes

126

what do the antigen which has migrated to regional lymph nodes during type 4 hypersensitivity mechanism activate

T cells (CD4+ve)

127

during type 4 hypersensitivity mechanism, where do sensitised T cells migrate back to

the skin, where they produce cytokines

128

in type 4 hypersensitivity mechanism, what do cytokines attract

macrophages which cause tissue damage

129

describe the whole of type 4 hypersensitivity mechanism

- APC resident in the skin process antigen and migrate to regional lymph nodes where they activate T cells (CD4+ve)
- sensitised T cells migrate back to the skin where they produce cytokines which attract macrophages which cause tissue damage e.g. contact dermatitis mediated by mast cells

130

explain how type 4 hypersensitivity mechanism is used to test for TB immunity

- injection of TB antigens (not the bacteria)
- perform a skin test, to check if there was a reaction to the TB antigen, if there is, they do not need the vaccination as they have natural immunity and can react to the TB antigen
- if there was no skin reaction, they need the TB vaccination

131

what is hypersensitivity

exaggeration/inappropriate immune response mediated by 4 types