Adaptive Immune System Flashcards
1
Q
What are antigen presenting cells required for?
A
To activate T-cells when there is an invasion
Help convey what the pathogen looks like
2
Q
Where are antigen presenting found?
A
In strategic locations
3
Q
What is the aim of the location of antigen presenting cells in strategic locations?
A
To optimise interactions with B and T cells
4
Q
What strategic locations are antigen presenting cells found in?
A
Skin
Mucous membranes
Lymphoid organs
Blood circulation
5
Q
How are antigen presenting cells found in the skin?
A
SALT (skin associated lymphoid tissue)
6
Q
How are antigen presenting cells found in the mucous membranes?
A
GALT (gut)
NALT (nasal)
BALT (bronchial)
7
Q
Give two examples of lymphoid organs
A
Lymph nodes
Spleen
8
Q
How are antigen presenting cells found in blood circulation?
A
Plasmacytoid
Myeloid dendritic cells
9
Q
What are antigen presenting cells involved in?
A
Pathogen capture
10
Q
What is the importance of pathogen capture?
A
The first step of adaptive immunity
11
Q
How are antigen presenting cells involved in pathogen capture?
A
Phagocytosis
Macropinocytosis
12
Q
What gets phagocytosed in pathogen capture?
A
The whole microbe
13
Q
What aids antigen presenting cells in phagocytosis during pathogen capture?
A
Antibodies and opsonins
14
Q
What is macropinocytosed in pathogen capture?
A
Soluble particles
15
Q
What does diversity in pathogen sensors allow?
A
The appropriate response to occur by the secretion of appropriate cytokines for both extracellular pathogens and intracellular pathogens
16
Q
Give 4 different types of antigen presenting cells
A
Dendritic cells
Langerhans’ cells
Macrophages
B cells (BCR)
17
Q
Where are dendritic cells found?
A
Lymph nodes
Mucous membranes
Blood
18
Q
What do dendritic cells present do?
A
T cells
B cells
19
Q
Where are Langerhans’ cells found?
A
Skin
20
Q
What do Langerhans’ cells present to?
A
T cells
21
Q
Where are macrophages found?
A
Various tissues
22
Q
What do macrophages present to?
A
T cells
23
Q
Where are B cells found?
A
Lymphoid tissues
24
Q
What do B cells present to?
A
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
