Adaptive Immune System Flashcards Preview

[ ESA 3- Infection and Immunity > Adaptive Immune System > Flashcards

Flashcards in Adaptive Immune System Deck (127):
1

What are antigen presenting cells required for?

To activate T-cells when there is an invasion
Help convey what the pathogen looks like

2

Where are antigen presenting found?

In strategic locations

3

What is the aim of the location of antigen presenting cells in strategic locations?

To optimise interactions with B and T cells

4

What strategic locations are antigen presenting cells found in?

Skin
Mucous membranes
Lymphoid organs
Blood circulation

5

How are antigen presenting cells found in the skin?

SALT (skin associated lymphoid tissue)

6

How are antigen presenting cells found in the mucous membranes?

GALT (gut)
NALT (nasal)
BALT (bronchial)

7

Give two examples of lymphoid organs

Lymph nodes
Spleen

8

How are antigen presenting cells found in blood circulation?

Plasmacytoid
Myeloid dendritic cells

9

What are antigen presenting cells involved in?

Pathogen capture

10

What is the importance of pathogen capture?

The first step of adaptive immunity

11

How are antigen presenting cells involved in pathogen capture?

Phagocytosis
Macropinocytosis

12

What gets phagocytosed in pathogen capture?

The whole microbe

13

What aids antigen presenting cells in phagocytosis during pathogen capture?

Antibodies and opsonins

14

What is macropinocytosed in pathogen capture?

Soluble particles

15

What does diversity in pathogen sensors allow?

The appropriate response to occur by the secretion of appropriate cytokines for both extracellular pathogens and intracellular pathogens

16

Give 4 different types of antigen presenting cells

Dendritic cells
Langerhans' cells
Macrophages
B cells (BCR)

17

Where are dendritic cells found?

Lymph nodes
Mucous membranes
Blood

18

What do dendritic cells present do?

T cells
B cells

19

Where are Langerhans' cells found?

Skin

20

What do Langerhans' cells present to?

T cells

21

Where are macrophages found?

Various tissues

22

What do macrophages present to?

T cells

23

Where are B cells found?

Lymphoid tissues

24

What do B cells present to?

T cells

25

What framework do antigen presenting cells follow?

Capture - process - present

26

How are extracellular microbes identified?

By their PAMPs

27

What recognises extracellular microbes PAMPs?

Dendritic cells

28

What happens when a dendritic cell recognises an extracellular microbes PAMP?

They activate humoral immunity

29

What does the activation of humoral immunity by dendritic cells involve?

The activation of antibodies and complement opsonising the microbes for phagocytosis

30

What can identify intracellular microbes?

Dendritic cells that contain receptors inside their cytosol to detect viruses

31

What happens when dendritic cells identify intracellular microbes?

They activate cell-dependant immunity

32

What does the activation of cell-dependant immunity by dendritic cells involve?

The activation of cytotoxic (CD8+) T cells
The activation of macrophages and antibodies

33

Why are macrophages and antibodies activated in the activation of cell-dependant immunity?

To start phagocytosis

34

What does the activation of both humoral and cell-dependant immunity involve?

The presentation of the antigen by Major Histocompatibility Complexes (MHC) to initiate immunity pathways

35

What codes for MHC molecules?

Genes found on chromosome 6

36

Where are class I MHC molecules found?

On all nucleated cells, including dendritic cells, macrophages, and B cells

37

Where are class II MHC molecules found?

Only on dendritic cells, macrophages, and B cells

38

What type of expression do MHC molecules show?

Co-dominant

39

What is meant by MHC molecules showing co-dominant expression?

Both parental genes are expressed

40

What is meant by MHC molecules being polymorphic?

There are different alleles among different individuals

41

What does the polymorphic nature of MHC molecules lead to?

Different alleles among different individuals

42

What do MHC I molecules do?

Present peptides from intracellular microbes

43

What do MHC II molecules do?

Present peptides from extracellular microbes

44

What structural feature do MHC molecules have?

Peptide binding cleft

45

What is the peptide binding cleft of a MHC molecule?

Variable region with highly polymorphic residues

46

How specific are MHC molecules?

Broad, despite their polymorphism

47

What is the result of MHC molecules having a broad specificity?

Many peptides can be presented by the same MHC molecule

48

What do MHC I molecules elicit a response in?

CD8+ T cells

49

What are CD8+ T cells also known as?

Cytotoxic

50

What do MHC II molecules elicit a response in?

CD4+ T cells

51

What are CD4+ T cells also known as?

T helper

52

Draw a diagram of an MHC I molecule

Add on website

53

Draw a diagram of an MHC II molecule

Add on website

54

What are the antigen presenting pathways?

Endogenous pathway
Exogenous pathway

55

Where does the endogenous pathway of antigen presenting occur?

In all cells

56

How does presentation occur in the endogenous pathway of antigen presentation?

Via the MHC I molecule

57

What happens in the endogenous pathway of antigen presentation?

An intracellular virus or tumour antigen is detected within the cell and targeted for degradation by a proteasome
The degraded microbe is now a mixture of antigenic peptides
These proteins are processed by the ER and each peptide is presented by a different MHC molecule to the CD8+ T cell

58

Where does the exogenous pathway of antigen presentation occur?

In antigen presenting cells only

59

How does antigen presentation occur in the exogenous pathway?

Via the MHC II molecule

60

What happens in the exogenous pathway of antigen presentation?

Exogenous antigens are taken in by phagocytosis or macropinocytosis, and broken down within an endosome.
The peptides of degraded antigen are then attached to the MHC II molecule and presented to CD4+ cells at the cell membrane

61

Are self or non-self peptides presented in antigen presentation?

Both

62

What does susceptibility to infections depend on?

The types of MHC molecules a person possesses

63

What are the potential responses in HIV-infected individuals?

Slow progressors
Rapid progressors

64

What MHC molecules are found in slow progressing HIV-infected individuals?

HLA-B27
HLA-B51
HLA-B57

65

What is the result of the MHC molecules found in slow progressing HIV-infected individuals?

MHC molecules present key peptides for the survival of the virus (unmutated), leading to an effective T cell response

66

What MHC molecules are found in rapid progressing HIV-infected individuals?

HLA-B35
Homozygote in HLA-1 alleles

67

What is the result of the MHC molecules found in rapid progressing HIV-infected individuals?

MHC molecules present mutated peptides (less critical peptides for the virus), so there is poor recognition by T cells, and poor T cell responses

68

What are the clinical problems with MHC molecules?

Major cause for organ transplant rejection
HLA association and autoimmune disease

69

Why do MHC molecules cause organ transplant rejection?

There can be a HLA molecule mismatch between donor and recipient

70

What is an allograph?

A donor that is the same species but genetically different from the recipient

71

Give an example of an autoimmune disease with HLA association`

Ankylosing spondylitis

72

What HLA molecules are related to ankylosing spondylitis?

HLA-B27
HLA-DQ2

73

In what % of alkylosing spondylitis patients is HLA-B27 found?

90%

74

In what % of ankylosing spondylitis patients is HLA-DQ2 found?

50-75% of patients

75

Where do T cells mature?

Thymus gland

76

What do T cells contain?

T cell receptors (TCR)

77

What do T cell receptors do?

Recognise the peptides presented by the MHC molecules

78

What do MHC molecules present antigen peptides to?

T cells

79

What do MHC II molecules present to?

CD4+ T cells

80

What happens as a result of MHC II presentation to CD4+ T cells with extracellular microbes?

The CD4+ T cells activate humoral immunity

81

What is activated in humoral immunity?

Antibodies (B cells)
Complement

82

What happens as a result of MHC II presentation to CD4+ cells with intracellular microbes?

The CD4+ T cells activate cell-dependant immunity

83

What is activated in cell-dependant immunity?

Antibodies (B cells)
Complement
Macrophages

84

What is activation of CD4+ cells by MHC II molecules required for?

The activation of CD8+ T cells, as well as activation by MHC I molecules

85

What do MHC I molecules present to?

CD8+ T cells

86

What are CD8+ T cells?

Cytotoxic T cells

87

What is the result of activation of CD8+ T cells?

Killing of the infected cell

88

What are the categories of CD4+ T cells?

Those for extracellular microbes
Those for intracellular microbes

89

What are the CD4+ cells for extracellular microbes?

TH2
TH17

90

What are the CD4+ cells for intracellular microbes?

TH1

91

What does the interaction of APCs and TH1 do?

Activates CD8, B cells, and macrophages

92

What is the result of the activation of macrophages by the interaction between TH1 and APCs?

Phagocytic activities kill opsonised microbes

93

What happens to the B cells activated by the interaction between APCs and TH1?

B cells create antibodies by isotype switching

94

What antibodies are produced from the B cells activated by the interaction between TH1 and APCs?

IgG2-3

95

What is the result of production of antibodies from B cells activated by the interaction between TH1 and APCs?

Kills opsonised microbes

96

What happens following CD8 activation by the interactions between APCs and TH1?

CD8 activates CTL (cytotoxic T lymphocytes)

97

What happens following the activation of CTL?

CTL interacts with MHC I receptors in the target infected cells, and releases perforins granzymes into the cell, leading to cell death

98

What is the result of interaction between APCs and TH17?

Activation of neutrophils

99

What is the result of activation of neutrophils by the interaction between APCs and TH17?

Phagocytosis

100

What is the result of interaction between APCs and TH2?

Activation between eosionphils, B cells, and mast cells

101

What is the result of activation of eosinophils by interaction between APCs and TH2?

Killing of parasites

102

What is the result of activation of B cells by the interaction between APCs and TH2?

Produces antibodies

103

What is the result of the production of antibodies by B cells activated by the interaction between APCs and TH2?

Phagocytosis and complement

104

What is the activation of mast cells by the interaction between APCS and TH2 associated with?

Local inflammation and allergies

105

How do B cells interact with T cells?

They can act as APCs to activate T cells
They can be activated by T helper cells

106

How can B cells act as APCs to activate T cells?

By presenting antigen peptides via MHC molecules

107

How can B cells be activated by T helper cells?

With the assistance of B cell receptors (BCR) found on the B cell itself

108

What happens to B cells once activated by a T helper cell?

They differentiate into plasma cells and secrete IgM as a primary response

109

What happens to B cells that don't differentiate into plasma cells?

They receive different signals and become germinal centre B cells within lymphoid follicles

110

What do germinal centre B cells within lymphoid follicles produce?

A high affinity antibody of a different type

111

Give an example of an antibody that can be produced by germinal centre B cells within lymphoid follicles

IgG

112

What can germinal centre B cells within lymphoid follicles later undergo?

Class switching

113

What happens to germinal centre B cells once they have undergone class switching?

They secrete higher affinity immunoglobulins

114

Give 3 examples of immunoglobulins that can be secreted by germinal centre B cells once they have undergone class switching

IgG
IgA
IgE

115

What do some germinal centre B cells become?

Quiescent memory B cells

116

What is the immune function of IgG?

Fc-dependant phagocytosis
Complement activation
Neonatal immunity
Toxin/virus neutralisation

117

Why is IgG important in neonatal immunity?

The neonate is protected for the first month of live by maternal IgG

118

What is the immune function of IgA?

Mucosal immunity

119

What is the immune function of IgE?

Immunity against helminths
Mast cell degranulation

120

Where does mast cell degranulation occur?

Allergies

121

What is the immune function of IgM?

Complement activation

122

What medical achievements have been derived from the study of the adaptive immune response?

Disease prevention
Immunoglobulin therapies
Immediate protection
Antibody based diagnostic tests

123

How has disease prevention been achieved from the study of the adaptive immune response?

Vaccination (active immunisation)

124

Where are immunoglobulin therapies used?

Immune deficiencies

125

How is immediate protection against infectious diseases given?

Passive immunisation

126

What happens in passive immunisation?

Antibody transfer

127

Where are antibody-based diagnostic tests used?

Infectious diseases
Autoimmune diseases
Blood type and HLA types