Introduction to the Immune System 2 Flashcards
(132 cards)
1
Q
Where are all our immune effector cells derived from?
A
From a common pluripotent progenitor cell (Hematopoietic stem cells/0 type in bone marrow
2
Q
What are all our immune effector cells a part of?
A
Our Hematopoietic blood system
3
Q
What are pluripotent progenitor cell?
A
Hematopoietic stem cells
4
Q
What are all our white blood cells called?
A
Leukocytes
5
Q
Name some white blood cells
A
Ganulocytes
Megakaryocyte
6
Q
Following stem cell division what can a daughter cell do?
A
- Divide
2. Differentiate
7
Q
Why is it a benefit that some of our daughter cells don’t differentiate but divided into more stem cells?
A
Means we have stem cells to replenish our blood system as we get older
8
Q
What is the first step of differentiation a stem cell can take?
A
Cells can either become:
- A Common lymphoid progenitor
- A common myeloid progenitor
9
Q
What do Common lymphoid progenitor give rise to?
A
B cells
T cells
NK cells
10
Q
What do Common myeloid progenitor give rise to?
A
Granulocytes and megakaryocytes (White blood cells)
Or dendrites
11
Q
What happens to a cell as it further differentiates?
A
They lose the ability to self renew
12
Q
Name our adaptive effector cells
A
B cells (which give plasma cells) T cells (which give activated T cells)
13
Q
Name our innate effector cells
A
NK cells (which give us activated NK cells) Dendritic cells (both mature and immature) Neutrophils Eosinophils Basophils Monocytes Mast cells Macrophages
14
Q
What lineage do dendritic cells come from?
A
Ether a myeloid or lymphoid lineage
15
Q
Name the only type if lymphocytes that are considered innate
A
NK cells
natural killer cells
16
Q
What are monocytes?
A
The precursor to macrophages
17
Q
Which is the mature effector: the macrophage or the monocyte?
A
The macrophage
18
Q
Where are immature monocytes found?
A
They circulate the blood
19
Q
Where are mature macrophages found?
A
Found in most tissues in sub mucosal layers.
20
Q
What is the function of monocytes and macrophages
A
- They are the first responders
- Phagocytic
- Engulf and kill pathogens and infected cells
- Clear dead cells and debris
- Bactericidal
- Present antigen to T cells
- Activate other immune cells
- Induce inflammation
21
Q
Do macrophages and monocytes have a long or short lifespan?
A
Long
22
Q
What does it mean a cell is phagocytic?
A
They can engulf and kill pathogens and infected cells
They can also clear dead cells and debris
23
Q
What is another name for granulocytes?
A
Polymorphonuclear leukocytes
24
Q
Name the 3 types of granulocytes
A
- Neutrophils
- Eosinophils
- Basophils
25
Which of the 3 types of granulocytes has a role in the immune response?
Neutrophils
26
What is the main role of Eosinophils and Basophils?
Main role is anti parasitic
27
Where are neutrophils found?
In the blood they migrate to infection sites
28
What are the functions of granulocytes?
1. Phagocytic
| 2. Bactericidal
29
Describe the life span of neutrophils
They have a short life span
30
What is pus made up of?
Dead neutrophils
31
Describe the morphology of neutrophils
They have lobes nuclei
| Their cytoplasms is speckled with cytotoxins
32
Where are immature dendritic cells found?
Under surface epithelia and in solid organs
| They migrate to lymph nodes and mature there
33
What are the functions of dendritic cells?
1. Phagocytic /Macropinocytosis
2. Take up antigen to present to adaptive arm
3. Activate cells of the adaptive arm
34
Where are natural killer cells found?
In the blood
| They migrate to infected tissues and tumours
35
What are the functions of natural killer cells?
1. Extracellular release of cytotoxic granules
2. Anti viral
3. Anti tumour
36
What type of cells are natural killer cells?
They are lymphocytes but are considered within the innate arm of the immune system
37
How do dendrites mature?
They are immature in the tissues but when they engulf bacteria and migrate they mature
38
What do dendritic cells do?
Take antigens from the site infection to the lymph nodes and they initiate the adaptive immune response
39
Describe the morphology of natural killer cells
They have a large single lobed nucleus
Bigger nucleus to cytoplasm
They have cytotoxins
40
Which cells do our NK cells kill?
Non- self cells
41
Name some phagocytic cells we have
1. Macrophages
2. Neutrophils
3. Dendritic cells
42
How to phagocytic cells decide what they want to engulf?
By using different receptors on their cell surface and within the cell
43
What do Fc receptors look for?
Antibody coated pathogens
44
What do compliment receptors look for?
Activated compliment molecules like: CRb
45
What do receptors on phagocytic cells look for?
1. Self cells
| 2. Non-self cells
46
What does PAMP stand for?
Pathogen associated molecular patterns
47
What do pattern recognition receptors look for?
Common structures we see in microbes (PAMPs)
48
What do we call common structures we see in microbes but not in higher organisms?
Pathogen associated molecular patterns (PAMPs)
49
Name the different types of PAMPS
1. Lectin like. Dectin 1
2. Scavenger receptors.
3. Toll like receptors
50
Give examples of toll like receptors
TLR4
| TLR6
51
What are toll like receptors always expressed as?
Diamers
| Some are homodiamers and some are hetero diamers
52
Describe how phagocytosis is activated
1. Compliment activation leads to deposition of c3b on the bacterial surface
2. Compliment receptor 1 (CR!) on macrophage binds to C3b on bacteria
3. Endocytosis of the bacterium by the macrophage
4. Macrophage membrane fuses creating a membrane- bounded vesicle (Phagosome)
5. Lysosomes fuse with the phagosomes forming phagolysosomes
53
What is a phagosome?
When macrophage membrane fuse creating a membrane-bounded vesicle
54
What are phagolysosomes?
When lysosomes fuse with phagosomes
55
How many toll like receptors do humans have?
10
56
What do TLRs detect?
They each recognise a distinct set of PAMP not found in vertebrates
57
Name some compounds toll like receptors detect
1. LPS of gram negative bacterial outer membranes
2. Lipoteichoic acids of gram positive cell walls
3. ds RNA
4. glucans such as zymosan (fungi)
58
What is Lipoteichoic acid recognised by?
TLR2 and TLR6
59
What is LPS recognised by?
TLR4
60
Where are TLRs expressed
Some are expressed on the cell surface and some inside the cell itself
Some are present on our epithelial cells
61
What do TLRs expressed inside the cell detect?
They detect molecules that may be present if we are under inter cellular attack like viruses or double stranded RNA
62
What do TLRs on epithelial cells do?
They trigger the cells to release communicating molecules like inflammatory cytokines and antimicrobial peptides
63
Name some of the antimicrobial mechanisms phagocytes employ once they have engulfed a pathogen
1. Acidification
2. Toxic oxygen derived products
3. Toxic nitrogen oxides
4. Antimicrobial peptides
5. Enzymes
6. Competiors
64
What is Acidification?
When a phagosome reduces the ph to around 3.5-4 which can lead to bacteriostatic or bactericidal
65
What is the respiratory burst?
It is triggered by phagocytes when they engulf a pathogen
| It results in the cells producing a lot of toxic oxygen species and nitrogen species
66
Name some toxic oxygen derived products
1. Superoxide O2-
2. Hydrogen peroxide H2O2
3. Singlet oxygen
4. Hydroxyl radical
5. Hypo-halite
67
Name some antimicrobial peptides macrophages produce
Cathelicidin (LL37)
68
Name some antimicrobial peptides neutrophils produce
```
Cathelicidin (LL37)
Alpha defensins
Beta defensives
Azurocidin
Bacterial permeability inducing protein
Lactoferrin
```
69
What enzymes do phagocytes produce to break down engulfed pathogens?
Lysozyme
| Acid hydrolyses
70
What does lysozyme do?
It breaks down cell walls of some gram positive bacteria
71
What do Acid hydrolyses do?
Break down ingested microbes
72
Name some Acid hydrolyses
Elastase and other proteases
73
Name some competitor molecules neutrophils produce
Lactoferrin
| Vitamin B
74
How does lactoferrin act as a competitor
It binds to iron ions and locks them up (sequesters iron ions) so that bacteria cannot use them
75
What are cytokines?
A small protein that affects the behaviour of other cells
| They act via a specific cytokine receptor expressed on the surface of the cell type they affect
76
What are chemokine?
A small chemoattractant protein that stimulates the migration and activation of cells
They act via specific receptors expressed on the surface of the cell type they affect
77
Cytokines produced by lymphocytes are called what?
Interleukins
78
Macrophages have an important role in what?
Co ordination of the immune response
79
What stimulates the macrophages to release cytokines?
Engulfing a pathogen
80
What do macrophages release?
Cytokines
| Chemokines
81
What do cytokines have a profound effect on?
Cells lining the blood vessels (our vascular endothelial)
| This makes the blood vessels to be more permeable (Leaky)
82
What is an advantage of cytokines making our blood vessels leakier?
Allows neutrophils to crawl out through the blood vessels near the infection site
Allows more plasma fluid to get to the infection site
83
What do chemokine cells do during an infection?
They draw the neutrophils to them telling them were to go
84
How does the compliment system help when they body suffers from an infection?
The formation of the membrane attack complex will allow for cell lysis to occur
85
Describe what steps the body takes initially when it is infected
1. Increased permeability which increases flow of plasma proteins (eg compliment) to site
2. Diameter of blood vessels increases this slows down blood flow
3. Clotting of some local micro vessels to inhibit infection spread
4. Endothelium now promotes leukocyte binding, increasing extravasion.
86
Describe the innate defence system
| Eg response time, cel recognition, memory
1. Responds on minutes-hours
2. Is always presnt
3. Has a limited range of antigen detection receptors
4. It is unchanged during the response
5. Genome encoded receptors
6. No memory
87
Describe the adaptive defence system
| Eg response time, cel recognition, memory
1. Take days-weals to response
2. Is usually silent till activated
3. Has a vast range of antigen receptors
4. Receptor recognition improves during the response
5. Receptors are not genome encoded
6. Has memory cells
88
What initiates the adaptive immune response?
Dendritic cells
89
What happens to innate response when the adaptive immune response is initiated?
Increases the efficiency of our innate response
90
Define antigen
Any molecule or fragment of molecule that is recognised by the specific receptors found on B and T lymphocytes
91
Define specificity
The ability of an antibody/ antigen receptor to distinguish a particular antigen from other antigens
92
What does adaptive immunity generate?
Vast range of recognition specificity
| Random generation of specificity
93
How are effector cells made?
1. A single progenitor cell gives rise to a large number of lymphocytes each with a different specificity
2. Removal of potentially self-reactive immature lymphocytes by clone deletion
3. Pool of mature naive lymphocytes forms
4. Proliferation and differential of activated specific lymphocytes to form a clone of effector cells
94
What does each immature B cell have>
A single and unique specificity for antigen
95
We need more than one individual cell of each specificity to combat an infection, how is there space in the haematopoietic system?
A particular cel encounters its complimentary antigen
| This causes the cell to proliferate and form a clonal army
96
How can Random receptor generation cause problems with recognising self and non self
As we produce self antigen receptors which have to be removed by clonal deletion when the cells are still immature in the bone marrow or thymus
Cells under apoptosis
97
What problems can occur if our body can't distinguish between self and non self
Our body will start attacking its own cells-> auto immune disease
98
What is clonal deletion?
Apoptosis of lymphocytes that have antigens complimentary to self cells
99
How is there enough space in the genome to encode all these receptors
The DNA sequences encoding antigen receptors in mature effector cells is different in progenitor / stem cells
100
What happens after clonal expansion?
Cells further differentiate to generate effector cells, plasma cells, memory cells and effector T cells as
101
What cells do B cells further differentiate into?
Memory cells and plasma cells
102
What cells do T cells further differentiate into?
Effector T cells and memory cells
103
What Is our B cell antigen receptor?
A membrane bound antibody molecule (immunoglobulin )
104
Name our B cell antigen receptor
mIg (membrane immunoglobulins)
| It binds ti antigen alone
105
What Is our T cell antigen receptor?
The T cell receptor can't recognise antigen on its own it can only see it is antigen if the antigen is complexed with another molecule called Major Histocompatibility Complex
106
What does MHC stand for?
Major Histocompatibility Complex
107
Define epitope
A site on an antigen that is recognised by specific lymphocyte receptors.
108
What are epitopes made of?
Carbohydrates, proteins or both:
109
Name the 2 types of epitopes
1. Continuous/Linear
| 2. Conformational / discontinuous
110
Describe continuous/ linear epitopes
They are a single fragment of polypeptide chain
111
Describe Conformational / discontinuous epitopes
amino acids that are not continuous in the polypeptide sequence but are brought together in 3D structure.
112
Where do B cell recognise epitopes?
Epitopes found on surface of antigen structure.
113
Where do T cell recognise epitopes?
more likely to recognise linear short peptide (often buried within antigen structure) presented by an MHC molecule. Continuous.
114
What are multivalent antigens?
One antigen that contains many epitopes
115
Describe multivalent antigens
Can be all the same (repeated sequence) but more commonly are chemically distinct.
Epitopes within folded myoglobin chain.
116
Which innate cell would you find in most tissues in the sub mucosal layer?
Mature macrophages
117
Which innate cell would you find circuiting the blood?
Immature monocytes
118
Neutrophils are what?
Granulocytes (Polymorphonuclear leukocytes)
119
Which receptor looks for antibody coated pathogens?
Fc receptors
120
Which receptors look for Activated compliment molecules like: CRb?
Complement receptors
121
Which receptors look and target non self cells?
Pattern recognition receptors
122
What are pathogen associated molecular patterns?
They are common structures we see in microbes that are detected by pathogen recognition receptors
123
What does TLR4 recognise?
LPS
124
What are Interleukins?
Cytokines produced by lymphocytes
125
How do cytokines act?
via a specific cytokine receptor expressed on the surface of the cell type they effect
126
What do TLR2 and TLR6 recognise?
Lipoteichoic acids
127
What does PRR stand for?
Pattern recognition receptors
128
What does PAMPs stand for?
Pathogen associated molecular patterns
129
What does TLR stand for?
Toll like receptors
130
What makes up 90% of our lymphocytes?
B and T cells
131
What is the name of an antigen that contains many epitopes?
Multivalent antigens
132
B and T cells make up what?
90% of our lymphocytes
