Introduction to specific immunity Flashcards
1
Q
Features of the innate immune system
A
- Recognises common pathogen molecules.
- The oldest form of immunity, present in all animals.
- We are born with it. - Immediate response to pathogen
- The first line of defense of the immune system.
- Identical response to the same pathogen.
2
Q
Fill in the blank boxes of the flow diagram representing the innate immune system.
A
3
Q
What are the physical barriers against infection?
A
- Skin
- Mucous membranes
4
Q
What is the main driver of the inflammatory response?
A
Histamine
5
Q
What cells are involved in the innate immune system?
A
- Neutrophils
- Macrophages
- Eosinophils
- Natural killer cells
6
Q
Features of the adaptive immune system
A
- Antigen-specific.
- Only found in vertebrates.
- Acquired by experience.
- On first exposure, it takes days to respond and creates memory.
7
Q
Fill in the blank boxes of the flow diagram representing the adaptive immune system.
A
8
Q
What two lymphocytes are involved in the adaptive immune system?
A
- B cells
- T cells
9
Q
What do B cells produce?
A
Antibodies
10
Q
What do antibodies do?
A
Bind to antigens
11
Q
What do antibodies aid in the adaptive immune response?
A
Phagocytosis of pathogens by neutrophils/macrophages
12
Q
What type of immunity is produced by B cells in the adaptive immune response?
A
Humoral immunity
13
Q
What are the two types of T cells in the adaptive immune response?
A
- T helper
- T cytotoxic
14
Q
What is the role of T helper cells in the adaptive immune response?
A
- Produce cytokines
- Help leucocytes eliminate foreign antigen-presenting cells
15
Q
What is the role of T cytotoxic cells in the adaptive immune response?
A
- Killing of foreign antigen-presenting cells
- Development of cellular immunity
16
Q
Label the adaptive immunity diagram from a to k
A
a - Parasites and worms
b - Extracellular bacteria
c - Fungi
d - Bacterial toxins
e - Intracellular bacteria
f - Viruses
g - Viral proteins
h - CD4 helper T cell
i - B cell
j - CD4 helper T cell
k - CD8 cytotoxic T cell
17
Q
Give descriptions a and b
A
18
Q
Fill in boxes a and b
A
19
Q
Fill in boxes a, b, and c
A
20
Q
Fill in the blank box
A
21
Q
Fill in boxes a, b and c
A
22
Q
In what time frame after infection does the innate immune response take action?
A
Immediately: 0-4 hours
23
Q
In what time frame after infection does the early induced innate response take action?
A
Early: 4-96 hours
24
Q
In what time frame after infection does the adaptive immune response take action?
A
Late: >96 hours
25
Label the adaptive immune response diagram from a to n
a - Primary lymphatic tissues
b - Pre-T cells
c - Mature B cells
d - Secondary lymphatic tissues
e - Mature T cells
f - Helper T cell
g - Antigen receptors
h - CD8
i - CD4
j - Activation of B cell
k - Activation of T cell
l - Plasma cells
m - Killer T cell
n - Antibodies
26
What do killer T cells do once they leave the secondary lymphatic tissues?
Attack the foreign antigen-presenting cells
27
What is the cell-mediated immune response directed against?
* Intracellular pathogens
* Viruses
* Some cancer cells
* Tissue transplants
28
What is the antibody-mediated immune response directed against?
* Extracellular pathogens
* Bacteria
29
What do antibodies do once they leave the secondary lymphatic tissues?
Bind to antigens of foreign antigen-presenting cell
30
Label the adaptive immune response diagram from a to e
a - Thymus
b - CD8+ T cell
c - CD4+ T cell
d - B cell
e - Killer CD8+ T cell
31
What cells does the immune response rely mostly on?
Immunocompetent B and T cells
32
Where do B cells continuously develop?
Within the bone marrow
33
What do T cells develop from and from where?
Pre-T cells from bone marrow that migrate to thymus to mature
34
When do the majority of T cells arise?
Before puberty
35
How long does T cell maturation go on for in the body?
Usually throughout life
36
What do B and T cells develop with maturity?
* Specific membrane-bound proteins
* CD4 and CD8 in T cells
37
What two immune responses occur in the adaptive immune response?
* Cell-mediated
* Antibody-mediated
38
What is cell-mediated immunity?
* Involved CD8+ T cell proliferation into cytotoxic T cells.
* Associated with intracellular pathogen targetting.
* Targets some cancerous and foreign tissue.
39
Three examples of intracellular pathogens
* Fungi
* Parasites (eg malaria)
* Viruses
40
What is antibody-mediated immunity?
* Involved in the differentiation of B cells to plasma cells.
* Immunoglobin and antibody production.
* Associated with antigen and replicating pathogen targetting in body fluids.
* Aided by CD4+ T helper cells.
41
What is the role of plasma cells?
Synthesize and secrete immunoglobins and antibodies.
42
What are antigens?
* Non-self molecular configuration.
* It may be part of a single foreign molecule or organism.
* Activate adaptive immune response.
43
What part of an antigen is recognised by a lymphocyte?
The epitope
44
Define immunogenicity
The ability to induce an immune response mediated by the production of specific T cells or specific antibodies.
45
Define immunoreactivity
The ability to react with antibodies or specific T cells.
46
What is a complete antigen?
An antigen with both immunogenicity and reactivity.
47
What do antigens that lack immunogenicity have to do to stimulate an immune response?
Combine with a larger carrier molecule.
48
What type of antigens do T cells respond to?
Protein antigens
49
What type of antigens do B cells respond to?
* Proteins
* Lipids
* Carbohydrates
* Nucleic acids
50
In what tissue/organ do antigens tend to come into contact with the immune system?
* Via blood to the spleen
* Via lymph to the lymph nodes
51
What initially happens to antigens being carried to the lymph nodes via the lymph?
They are trapped by the reticular fibres of the reticular cells.
52
How are antigens trapped on mucosal membranes?
By mucosa-associated lymphatic tissue (MALT) mucus
53
What does TCR stand for?
T cell receptor
54
What does CD stand for?
Cluster of differentiation
55
What does ITAM stand for?
Immunoreceptor tyrosine-based activation motif
56
Label the mature TCR diagram from a to f
a - TCR
b - recognition
c - CD3
d - CD3
e - ITAMs
f - Signalling
57
What does MHC stand for?
Major histocompatibility complex
58
How many alleles are responsible for the production of an MHC?
12
59
Where is the MHC found?
Expressed on the surface of cells important in the adaptive immune response
60
What does the MHC do?
* Guide T cell recognition of antigen
* Bind epitopes of antigens and present to T cells
61
What is the morphism of MHCs?
* Highly polymorphic
* Unique to each individual - except in identical twins
62
Label MHC class a and b
63
Another term for hiistocompatability complex
Human leucocyte antigen (HLA)
64
What cells express MHCs?
Every cell in the body apart from red blood cells
65
What is histocompatability?
The presentation of self-antigens on the plasma membrane that make the cell compatable with the host immune system.
66
Two types of MHC
* Class I
* Class II
67
Where are MHC class I found?
Plasma membrane of all body cells apart from the red blood cells.
68
Where are MHC class II found?
Antigen presenting cells such as thymic cells and T cells.
69
What is responsible for rejection of donor tissue?
Foreign MHC expression of foreign cells of donor tissue.
70
What is tissue typing?
Putting people's MHC expression into groups based on MHC similarity.
71
What is antigen processing achieved by?
T and B cells recognising the antigen
72
Where do B cells recognise antigens?
Body fluids
73
How do T cells recognise antigens?
When antigens are presented to them by the host MHC.
74
What type of MHC protein is used to recognise foreign antigens?
Non-self source MHC proteins
75
Two ways that foreign antigens can be processed
* Exogenous antigen processing
* Endogenous antigen processing
76
Describe steps 1-5 of exogenous antigen processing
77
Label the diagram of exogenous antigen processing from a to d
a - Antigen
b - Phagosome/endosome
c - Antigen-presenting cell (APC)
d - MHC-II
78
Where does exogenous antigen processing occur?
Body fluids
79
What are exogenous antigens initially processed by?
Antigen-presenting cells (APC)
80
3 types of antigen-presenting cell
* Macrophages
* B cells
* Dendritic cells
81
How do antigen-presenting cells exogenously process an antigen?
1. Ingest
2. Digest
3. Fusion to MHC-II proteins
4. Exocytosis
5. Presentation
82
Where do antigen-presenting cells migrate to after exogenous antigen processing?
Lymphatic tissue to be presented to T cells
83
Define endogenous antigen
Antigen produced within a cell
84
How are endogenous antigens processed?
1. Digestion
2. Fragments fuse with MHC-I proteins in a vesicle
3. Endocytosis of vesicle
4. Presentation of MHC-I antigen complex
85
Do T cells recognise free antigens?
No
86
When are antigens recognised by T cells?
When they are presented by an MHC protein on an antigen-presenting cell.
87
What part of an antigen is recognised by T cells?
The epitope
88
Label the empty blue boxes from a to d
89
What are the two stages of T cell activation?
1. Initial binding of T cell to antigen-presenting cell
2. Co-stimulation
90
How many known co-stimulants of T cell activation are there?
20+
91
What are two co-stimulants?
* Cytokines such as interleukin 2
* Plasma cell membrane molecules
92
What does a lack of co-stimulation result in?
T cell anergy
93
What is T cell anergy?
T cell tolerance to an antigen
94
What is required to fully activate a T cell?
* Antigen-presenting cell
* Co-stimulant
95
What does a T cell do when fully activated?
T cell proliferation and differentiation
96
Where in the body does T cell proliferation and differentiation occur?
Secondary lymphatic organs and tissues like the tonsils.
97
Three main types of T cells
* T helper cells
* T cytotoxic cells
* T memory cells
98
What cells to helper T cells normally develop from?
CD4+ T cells
99
Which antigen MHC is recognised by helper T cells?
Antigen MCH-II
100
Function of T helper cell
* Secretes interleukin 2 which triggers T cell proliferation fo costimulate quiescent T helper cells and cytotoxic T cells.
* Can also enhance proliferation of B cells and natural killer cells.
101
Label the T cell activation diagram from a to m
a - Costimulation by IL-2 from T helper cells
b - Inactive CD8+ cell
c - CD8
d - MHC-I
e - CD8+ T cell
f - Inactive CD4+ cell
g - MHC-II
h - CD4
i - CD4+ T cell
j - Activated T helper cell
k - Activated cytotoxic T cell
l - CD4+
m - CD8+
102
What are cytokines?
Small hormones that can stimulate or inhibit cellular differentiation, proliferation and growth.
103
What effect do cytokines have on immunocompetent cell function?
An enhancing effect
104
What are cytokines secreted by, in the immune system?
All communicating leucocytes.
105
What are the most commonly known immunity-related cytokines?
* Interleukins 1-5
* Tumour necrosis factor
* Transforming growth factor beta (TGF-β)
* Gamma interferon (γ-IFN)
* Alpha and beta interferons
* Lymphotoxin
* Perforin
* Macrophage migration inhibiting factor
106
What is cytokine therapy?
The medical application of cytokines to treat medical conditions to do with immunity regulation.
107
What are cytotoxic T cells derived from?
CD8+ cells
108
What do cytotoxic T cells recognise?
Antigen-MHC-I on virally infected cells, on cancerous cells and on some transplanted cells.
109
What causes cytotoxic T cells to become cytolytic?
If antigen recognition and costimulation with cytokines like IL-2 happens.
110
What cell secretes cytokines that costimulate cytotoxic T cells?
T helper cells
111
What causes T helper cells to produce costimulating cytokines for cytotoxic T cell?
Recognition of antigen-MHC-II by the helper T cell
112
What happens to cytotoxic T cells once activated?
They rapidly proliferate and destroy target cells by secreting perforin or lymphotoxin.
113
How do cytotoxic T cells activate phagocytes at the site of infection?
By secreting gamma interferon
114
Label the cytotoxic T cell diagram from steps 1-3
115
Label the cytotoxic T cell activation diagram from a to e
a - Activated cytotoxic T cell
b - Lymphotoxin
c - Perforin
d - Virus-infected body cell
e - Cytolysis
116
What is perforin?
A protein released by T killer cells of the immune system that causes cell death by causing lesions and pores to form in the target cell's membrane.
117
What is lymphotoxin?
A cytokine from the immune system that causes target cells to change the binding properties of proteins in their plasma membranes so that phagocytes can engulf them.
118
What gives rise to memory T cells?
T cells that remain after an infection
119
Function of memory T cells
Allow rapid response to reinvasion of the same pathogen before signs and symptoms show
120
After how much gestation do progenitor T cells migrate to the thymus?
* 11 days in mice
* 8-9 weeks in humans
121
What does T and B cell maturation involve?
Rearrangements of germline TCR genes and expression of various membrane markers.
122
What are developing T cells in the thymus called?
Thymocytes
123
What do thymocytes do whilst they develop in the thymus?
Proliferate and differentiate into distinct sub-populations of mature T cells.
124
Label the diagram of the passage of the T cell throughout its development from a to e
a - bone marrow
b - thymus
c - gut-associated lymphoid tissue
d - spleen
e - lymph node
125
In the proliferation of progenitor T cells, what proportion of thymocytes undergo apoptosis?
Approximately 98%
126
What type of selection is MHC restriction of thymocytes?
Positive restriction
127
What type of selection is the deletion of autoreactive thymocytes?
Negative selection
128
Label the diagram of T-lymphocyte development in the thymus from a to l
a - cortex
b - medulla
c - capsule
d - trabeculae
e - sub-capsular epithelium
f - cortico-medullary junction
g - Hassall's corpuscle
h - cortical epithelial cell
i - thymocyte
j - medullary epithelial cell
k - dendritic cell
l - macrophage
129
Where do cortical epithelial cells in the thymus originate from?
Thymus
130
Where do thymocytes in the thymus originate from?
Bone marrow
131
Where do medullary epithelial cells in the thymus originate from?
Thymus
132
Where do dendritic cells in the thymus originate from?
Bone marrow
133
Where do macrophages in the thymus originate from?
Bone marrow
