Intro to immunology Flashcards
1
Q
Define innate immunity
A
Non-specific, distinctive and does not depend on lymphocytes
2
Q
Define adaptive immunity
A
Specific acquired immunity, requires lymphocytes and antibodies
3
Q
Define humeral immunity
A
Mediated by macromolecules found in ECF such as antibodies and complement proteins
4
Q
Size of Neutrophils
A
10-14 micrometer
5
Q
How many Neutrophils per mm^3 blood
A
3-11,000
6
Q
Life span of neutrophils
A
6hours-12 days
7
Q
What adhesion molecule is produced by neutrophils
A
CD66b
8
Q
What immunity do neutrophils have a great role in
A
Innate
9
Q
What are the two main intracellular granules in neutrophils
A
Primary lysosomes - myleloperoxidase, muramidase, acid hydrolyses and defensives
Secondary lysosomes (lysozyme and lactoferrin)
10
Q
Role of primary lysosomes
A
Combine with phagosomes containing microbes to digest them
Complement receptors
Secrete superoxides
11
Q
Why are myeloperoxidases needed
A
Allows neutrophils to carry out antimicrobial activity
12
Q
Why are superoxides needed
A
Kill microbes
13
Q
Size of monocytes
A
14-24 micrometers
14
Q
How frequent are monocytes
A
100-700 per mm^3 blood
15
Q
Lifespan of monocytes
A
Months
16
Q
What receptors do monocytes express
A
CD14
17
Q
Role of monocytes
A
Innate and adaptive immunity
Phagocytosis
Ag Presentation
18
Q
What happens to monocytes after entering the tissues
A
Differentiate into macrophages
19
Q
What compound are contained in monocyte lysosomes
A
Peroxidase
20
Q
What receptors do monocytes have
A
- FC
- Complement receptors
- PRR
- Toll-like
- Mannose receptors
21
Q
What do FC receptors bind to
A
Antibodies that are attached to infected cells or invading pathogens
22
Q
Where do macrophages reside
A
Tissues
23
Q
Lifespan of macrophages
A
Months/years
24
Q
What type of macrophage are found in the liver
A
Kupffer cells
25
What type of macrophage are found in the brain
Microglia
26
Role of macrophages
Phagocytosis and Ag presentation
27
What cells are the first line of non-self recognition
Macrophages
28
Main role of macrophages
Remove microbes and tumour cells
| Present Ag to T-cells
29
What enzyme is found in macrophage lysosomes
Peroxidase
30
Size of an eosinophil
10-14 micrometer
31
Frequency of eosinophil
100-400 per mm^3 blood
32
Lifespan of eosinophil
8-12 days
33
What receptors do eosinophils express
CD125
34
Role of eosinophils
Associated with parasitic infections and allergic reactions
35
What is contained in eosinophil granules
Major Basic Protein - potent toxin for helminth worms
36
Role of MBP
Activates neutrophils
Induces histamine release from mast cells
Provokes bronchospasm
37
Size of basophil
10-12 micrometer
38
Frequency of basophil
20-50 per mm^3 blood
39
Lifespan of basophil
2 days
40
What cell are basophils similar to
Mast cells
41
What receptors do Basophils express?
FcεR1 (IgE receptors)
42
What happens when IgE binding occurs
Degranulation - releases histamine
43
Role of basophils
Response to parasitic infections and allergic reactions
44
Size of mast cell
10-14 micrometers
45
Where are mast cells active
Only in tissues - circulates inactive form in the blood
46
What receptors do mast cells have
FcεR1
47
What happens when IgE its bound to
De-granulation releasing histamine
48
Size of T cells
5-12 micrometer
49
Frequency of T cells
300-1500 per mm^3 blood
50
Lifespan of T cells
hours to years
51
Where do T cells mature
Thymus
52
What receptor do T lymphocytes express
CD3
53
Role of T helper cells 1
Immune response to intracellular pathogens
54
Receptor on T helper cells 1
CD4
55
Role of T helper cells 2
Produce antibodies - extracellular pathogens
56
Receptors on T helper cells 2
CD4
57
Role of cytotoxic T cells
Kill cells directly
58
Receptor on cytotoxic T cells
CD8
59
Role of T regulatory cells
Regulate immune responses 'dampen'
60
Receptors on T regulatory cells
FoxP3
61
Where are T cells found (3)
1. Blood
2. Lymph nodes
3. Spleen
62
Size of B cells
5-12 micrometer
63
Frequency of B cells
300-1500 per mm^3 blood
64
Lifespan of B cells
Hours to years
65
Where do B lymphocytes mature
Bone Marrow
66
What receptors do B cells express
CD19 and CD20
67
Role of B cells
Recognise Ag displayed by APC
Express membrane bound antibody on cell surface
Differentiate into plasma cells that make antibodies
68
Where are B cells found
Blood
Lymph Nodes
Spleen
69
What receptor do NK cells express
CD56
70
Where are NK cells found
Spleen/tissues
71
Role of NK cells
Kill virus infected cells
Tumour cells
by triggering apoptosis
72
How many compliment factors are present in the immune system
20
73
Classification of complement factors
Classical
Alternative
Lectin
74
Two properties of antibodies
1. Bound to b cells
| 2. Soluble
75
Name the 5 distinct classes of antibodies
1. IgG
2. IgA
3. IgM
4. IgD
5. IgE
76
Define antibody
Protein produced in response to an antigen
77
Define antigen
A molecule that reacts with preformed antibody and specific receptors on T and B cells
78
Define Epitope
Part of an antigen that binds to the antibody/receptor binding site
79
Define affinity
Measure of binding strength between an epitope and an antibody binding site
80
Most common antibody in the body
IgG
81
How many chains is IgG made of
4 peptide chains: Two heavy and two light joined by disulphide bonds
82
Role of Fab fragment on antibody
Binds to antigens (the light and heavy chain ends of the antibody - or tips of the Y shape)
83
Proportion of antibodies in the blood made up by IgM
10%
84
Shape of IgM
Pentagon
85
How are the chains of IgM attached together
J chains
86
Where is IgM mainly found
Blood
87
Can IgM move into tissues and why
No, too big to pass through endothelium
88
Role of IgM
Initial contact with Ag
89
What is the purpose of the monomeric form (mIgM)
It acts as an antigen-specific receptor on B cells
90
Proportion of antibodies in the blood made up by IgA
15%
91
Is IgA a dimer
No, it's mostly a monomer in humans (80% of them are)
92
Where is IgA commonly found
Saliva, milk and genitourinary secretions (known as sIgA)
93
How is sIgA held together
J chain and secretory component
94
Proportion of antibodies in the blood made up by IgD
1%
95
Where is IgD found
Mature B cells (transmembrane monomeric form)
96
Proportion of antibodies in the blood made up by IgE
0.05%
97
Role of the cytokine IFN (Interferons)
Induce a state of antiviral resistance in uninfected cells
| Limit spread of viral infections
98
What cells produce IFN alpha and beta
Viral infected cells
99
What secretes IFN gamma
Released by activated TH1 cells
100
What is the pro-inflammatory interleukin
IL1
101
What is the anti-inflammatory interleukin
IL-10
102
Role of IL
Causes cells to divide, differentiate and secrete factors
103
Role of Colony Stimulating Factors
Involved in directing division and differentiation on bone marrow stem cells
104
What are CSF precursors of
Leukocytes
105
Role of TNF
Mediate infiammatorio and cytotoxic reactions
106
Role of chemokine
Direct movements of leukocytes from blood stream into tissues or lymph organs by binding to specific receptors on cells
107
What do CXCL act on
Neutrophils, T and B cells
108
What do CCL act on
Monocytes, lymphocytes, eosinophils and basophils
109
What do CX3CL act on
T and NK cells
110
What do XCL act on
T cells
111
What is innate immunity composed of
Barrier to pathogens
112
What is the main component of adaptive immunity
Memory cells
113
What barriers does the innate immunity use to defend against pathogens
Dermis and Epidermis
Skin secretions (pH 3-5)
114
Use of tears in pathogenic defences
1. Lysosomes present
115
What is the purpose of mucous membranes
1. Saliva and tears and mucous secretions can trap bacteria
| 2. Cilia beats microbes away
116
What physiological barriers are there for pathogenic defence
1. Pyrexia Prevents micro-organism growth
117
Role of gastric acidity in innate immunity
Destroys pathogens
118
How does gastric acidity effect children vs adults
Less acidic in children so susceptible to infection
119
What are the three physiological factors of the innate immunity
pH
Gastric Acidity
Oxygen Tension
120
What follows breach of pathogens following failure of innate immunity
Inflammation
121
Define acute inflammation
Complete elimination of a pathogen followed by resolution of damage, disappearance of leukocytes and full regeneration of tissue
122
What two ways can microbes detect microbes
1. PRR on host cells identified
2. Identify PAMPs on microbes (molecules produced by pathogens or abnormal activity caused by them)
3. Toll-like receptors on leukocytes allows recognition
123
Three roles of the complement system
1. Lyse microbes directly (membrane attacking)
2. Increase chemotaxis (C3a and C5a)
3. Opsonisation (C3b)
124
How does chemoattraction take place in extravasation
Cytokines cause endothelial cells near site of infection to express cellular adhesion molecules (selection)
125
Describe the adhesion process of extravasation
1. Ligans on leukocytes bind to selection with small affinity, slow down and roll along inner wall
2. Chemokines released by macrophages activate rolling leukocytes and cause surface intern molecules to go from low to high affinity
126
What two pathways exist in macrophage and neutrophil killing
Oxygen dependant
| Oxygen indépendant
127
Describe the Oxygen dependant pathway
Superoxides converted to hydrogen peroxides and hydroxide ions
NO also produced which causes vasodilation for extravasation
128
Describe the oxygen independent mechanism of killing
Defensives insert into pathogenic membranes and lysozyme change pH
129
Where is C reactive protein produced
Liver
130
Role of C reactive proteins
Binds to bacterial cell walls
| Promotes opsonisation
131
What do C reactive proteins bind to
C1q receptors to activate complement system
132
Role of Mannose binding Lectin
Binds to lectin and promotes opsonisation
Activates complement system
133
Role of surfactant protein-A
Binds haemagglutinin in influenza - reduces ability of virus to infect cells
134
What cell protects against intracellular microbes
T cells
135
What cell protects against extracellular microbes
B cells
136
Do T cells respond to soluble antigens
No
137
What is T cell selection
T cells recognise self antigens and are killed in the thymus as they mature
138
What structure are T cell receptors similar to
Fab structure on Ig antibodies
139
What is the role of the Major Histocompatibility Complex
Display peptides from self or non-self proteins on the cell surface - invasion alert
140
Where are MHC I glycoproteins found
ALL nucleated cells
141
Where are MHC II glycoproteins found
ONLY on APC
142
Where are MHC III found
Complementary system
143
What are MHC I and II coded by
HLA
144
How do the MHC interact with the T cells
MHC molecule presents peptide which is recognised by T cell when they bind
145
How many AA are in MHC I
8-10
146
How many AA are in MHC II
13-24
147
What cells do MHC I interact with
CD8 T cells
148
What happens when MHC I of host cell binds to CD8
Infected cell with intracellular pathogen is destroyed
149
What do MHC II bind to
CD4
150
What happens when MHC II of host cell binds to CD4
Help B cells make Ab to extracellular pathogen and help directly kill
151
Describe the process of Ag Recognition and Activation of T cells
1. CD28 on T cell binds to CD80/86 on APC
| 2. IL-2 secreted and binds to IL-2 receptor on T cells (autocrine) activating T cell.
152
How can CD4 further differentiate
Into TH1 due to IL-12hi
| Into TH2 due to IL-12lo
153
Role of IFN gamma
Kill intracellular pathogens
154
From what cells are IFN-gamma produced
TH1
155
Describe the activation of CD8
1. MHC I binds to TCR on inactive CD8
2. CD8 matures and releases chemokine
3. Releases perforin and granulising
156
Role of perforin
Apoptosis
157
Role of granulysin
Killing pathogens
158
Describe activation of CD4
1. APC presents Ag with MHC to naive CD4
2. High levels of IL-12 cause naive CD4-> mature CD4
3. Clonal expansion
4. CD4 recognises Ag on infected cells via re ephors
5. CD4 secretes INF gamma which induces apoptosis
159
How many immature B cells are we born with
10^9
160
Describe the process of Antigen presenting of B cells to T cells
1. IgM binds Ag
2. Phagocytosis
3. Peptide displayed with MHC II
4. CD4 binds to MHC II
5. APC eats Ag and presents to CD4 and T cells via MHC II
6. CD4 turn into T-helper 2 cells
7. TH2 secretes IL4, 5, 10 and 13
8. Clonal Expansion of B cells -> Plasma cells and Memory B cells
