4. Immunology Flashcards
(118 cards)
1
Q
2 different immune systems
A
- non-specific/innate immunity
- specific/adaptive immunity
2
Q
Non-specific / Innate immunity
A
- first line of defense
- no pathogen recognition
- same response each time
3
Q
Specific / Adaptive immunity
A
- requires pathogen recognition
- faster response with 2nd exposure to pathogen: memory cells formed
4
Q
primary lymphoid organs is the place where…
A
stem cells divide and immune cells develop
5
Q
primary lymphoid organs (2)
A
- bone marrow (yolk sac and fetal liver in embryo)
- thymus
6
Q
bone marrow is where
A
- immature B cell and T cell are produced
- B cells mature
7
Q
thymus key functions
A
- T cell maturation site
- contains T cells, dendritic cells, epithelial cells and macrophages
- atrophies after maturity
8
Q
secondary lymphoid organs is where…
A
most immune responses occur
9
Q
secondary lymphoid organs (3)
A
- lymph nodes
- spleen
- lymphoid nodules
10
Q
lymph nodes
A
- scattered throughout the body
- contain macrophages that phagocytose microbes entering lymph
11
Q
spleen
A
- removes microbes and old erythrocytes
- largest lymphoid organ
12
Q
lymphoid nodules
A
tonsils, appendix, Peyer’s Patches and Mucosal-Associated Lymphoid Tissues (MALT)
13
Q
Immune cells are produced by…
A
lymphoid and myeloid stem cells
14
Q
lymphoid cells: lymphocytes
A
- T cells
- B cells
- NK cells
15
Q
myeloid cells
A
- neutrophils
- monocytes
- eosinophils
- basophils
- mast cells
16
Q
neutrophils
A
phagocytes responsible for bacteria eating
17
Q
monocytes
A
become macrophages and dendritic cells (phagocytes)
18
Q
eosinophils
A
destroy parasites
19
Q
basophils
A
release chemicals: i.e histamine
20
Q
mast cells
A
release chemicals: i.e. histamine
21
Q
myeloid cells filled with secretory granules
A
- eosinophils
- basophils
- mast cells
22
Q
innate immune system (def)
A
ability of body to defend against microbes/foreign substances without recognition of the invading pathogen
23
Q
2 lines of defense in innate immunity
A
- 1st line of defense = physical barriers
- 2nd line of defense = cellular and humoral factors
24
Q
first line of defense
A
barriers to entry, creating unpleasant environment for microorganisms
25
physical and mechanical barriers to first line of defense
- skin: water resistant
- tight junctions in epithelia
- mucus
- hair and cilia
26
chemical and microbiological barriers to first line of defense
- normal flora
- secretions:
--> sebum (low pH)
--> lysosomes
--> gastric juice
27
second of line of defense
humoral and cellular factors
28
humoral response (def)
includes substances that are dissolved in tissues
29
humoral factors (4)
- interferons
- complement: C3b
- iron-binding proteins: transferrin
- antibodies
30
inflammation
non-specific response to tissue damage
31
4 inflammation signs
- redness
- heat
- pain
- swelling
32
3 stages of inflammation
1. vasodilation
2. Emigration of phagocytes
3. tissue repair
33
Inflammation: vasodilation
- widening of blood vessels to increase blood flow and stretch capillary
- increased permeability of capillaries to allow substances to reach damaged site
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inflammation: emigration of phagocytes
1. Chemotaxis: chemically stimulated movement of phagocytes
2. Margination: phagocyte sticks to endothelial cel
3. Diapedesis: phagocyte crosses capillary wall to reach site of injury
35
what triggers vasodilation?
signals from fixed-tissue macrophages
36
specific role of neutrophils in inflammation
- die in the process of killing bacteria
- form NETs: Neutrophil Extracellular Traps when they lyse
- sticky pus produced: mixture of dead bacteria and neutrophils, to prevent more bacteria moving further
37
type I interferons
prevent viral replication by binding to uninfected cells, allowing them to produce antiviral proteins
38
C3b Complement
plasma protein that sticks to bacteria (opsonisation) to make it more recognisable for phagocytes
39
iron-binding proteins: Transferrin
binds to iron so it can't be used by bacteria to grow/replicate
40
cellular factors (3)
- Natural Killer cells (NK cells)
- phagocytes
- cells with inflammatory mediators
41
Natural Killer cells (NK cells)
lymphocytes that target virus-infected cells and cancer cells:
- if a cell lacks MHC-I, NK cell can only bind to its activating ligand which activates NK cell for killing
- normal body cells: NK cells can bind to MHC-I and activating ligand --> stable configuration: no killing activated
42
cells with inflammatory mediators
- basophils
- mast cells
- eosinophils
43
phagocytes
non-specifically engulf microbial invaders
44
different types of phagocytes
- fixed-tissue macrophages: already in tissue
- neutrophils: recruited at injury site
- monocytes: become macrophages and dendritic cells
45
examples of fixed-tissue macrophages
PAMPs and TLRs
46
phagocytosis (process)
1. endocytosis of microbe: phagosome formed
2. lysosome fuses with phagosome to form phagolysosome
3. phagolysosome releases end products into and out of cell
47
Pattern Recognition Receptors (PRR)
recognise Pathogen Associated Molecular Patterns (PAMPs) and send out signals
48
example of PRR
Toll-Like Receptors (TLRs) are transmembrane receptors with:
- extracellular domain for pathogen recognition
- intracellular signalling domain to request cytokines
49
Antigen Presenting Cells (APCs)
link innate and adaptive immunity
50
epitope
part of the antigen recognised by the antibody
51
how is innate immunity linked to specific immunity?
1. dendritic cell kills bacteria
2. dead bacteria attached to dendritic cell
3. dendritic cell carrying dead bacteria travels to lymph node via lymphatic system
4. lymphocytes activated in lymph node
52
Specific / Adaptive immunity (def)
ability of the body to defend against specific microbes and foreign substances, involves memory
53
what cell type does the specific immune system involve
lymphocytes: B and T cells
54
on which cells is MHC-I expressed?
all nucleated cells
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on which cells is MHC-II expressed?
on Antigen-Presenting Cells (APCs)
56
antigen presentation process
T cell receptors recognise antigens only when they are associated with MHC-II
57
Antigen Presenting Cells (APCs) include
- dendritic cells
- macrophage
- B cell/lymphocyte
58
how do APCs present exogenous antigens with MHC-II?
1. ingestion of antigen by APC
2. digestion of antigen into peptide fragments
3. synthesis + packaging of MHC-II molecules
4. vesicles containing antigen peptide fragments and MHC-II molecules fuse
5. antigen peptide fragments bind to MHC-II molecules
6. vesicle undergoes exocytosis: antigen-MHC-II complexes inserted into plasma membrane
7. complex expressed to T cells in lymph nodes
59
antigen characteristics (2)
- reactivity
- immunogenicity: can provoke immune response
60
role of helper T cells
activated B cells and cytotoxic T cells
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role of B cells
transform into plasma cells and secrete antibodies
--> involved in humoral response with antibodies and complement
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role of cytotoxic T cells
attack infected body/foreign/cancer cells
-> cell-mediated response
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3 stages of adaptive immune response
1. recognition of antigen by lymphocytes
2. lymphocyte activation
3. attack launched by activated lymphocytes + their secretions
64
How are Helper T cells activated?
1. Specific recognition between MHC-II and peptide-TCR (T cell receptor)
2. Co reception of CD28-B7 --> checkpoint inhibition
3. cytokine release from APC which stimulates T helper cell
65
checkpoint inhibition
CTLA4 or PD-1 displaces CD28, inhibiting T cell activation
66
how to get increased T cell activation through checkpoint inhibition
antibodies generated to bind to CTLA4 so it won't displace CD28
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CD4 required in activation of...
T helper cells
68
antibodies produced by...
plasma cells (which come from B cells)
69
antibodies are part of a group of proteins called...
globulins -> immunoglobulins
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heavy chains of antibody corresponds to...
Fc region
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light chains of antibody corresponds to...
FAB region
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Fc region
constant: same in all antibodies of a class
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FAB region
variable: determines specificity of antigen
-> antigen binding site
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IgG
most numerous, produced after IgM during immune response
-> 2 binding sites
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IgA
found in MALT and breast milk
-> dimer: 4 binding sites
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IgM
first formed during immune response: responsible for complement activating cascade
-> 10 binding sites
77
plasma cells function
secrete specific antibodies
78
memory cells purpose
allow faster response if antigen seen again
79
active immunity
long-lasting protection: memory cells are involved and is the person's own immune system response to pathogen
80
natural, active immunity example
catching Influenza by someone coughing on the bus
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artificial, active immunity example
vaccination
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passive immunity
temporary protection: no memory cells involved since the person receives antibodies from someone else
83
natural, passive immunity example
IgG from placenta or IgA from breast milk
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artificial, passive immunity example
receiving serum containing antibodies from person/animal
85
functions of antibodies (6)
- neutralisation
- agglutination
- precipitation
- activating complement
- opsonization
- antibody-dependent cellular cytotoxicity
86
neutralising antigen
antibody binds to antigen so I can't do more damage
87
agglutinating antigen
makes it harder for microbe to move/divide and easier for phagocyte to recognise
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precipitating antigen
prevents antigen from moving
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activating complement
antibody bins to antigen, leading to C1 activation and formation of Membrane Attack Complex
90
opsonisation
antibody sticks to pathogen surface and prepares for eating
91
antibody-dependent cellular cytotoxicity
increases effectiveness of NK cells: interaction between antibody and Fc receptor activates release of granzymes and perforin
92
immunocompetence
development of antigen receptor
93
RAGs purpose
Recombination Activating Genes: splice out gene segments from V, D, J
94
TdT purpose
Terminal deoxynucleotidyl Transferase: adds single bases on VDJ segments to increase variation
95
what determines which antibody will be produced from the mRNA transcript?
the control region gene expressed
96
immune tolerance
clonal deletion or clonal inactivation of cells that:
- don't recognise MHC-II
- recognise MHC-I
97
percentage of T cells destroyed after production
95%
98
activation of Cytotoxic T cells
1. infected body cells synthesise MHC-I molecules
2. destroyed antigen (peptide fragments) are bound to MHC-I
3. antigen-MHC-I complex packaged
4. antigen-MHC-I complex inserted into plasma membrane
99
CD8 required in activation of...
Cytotoxic T cells
100
factors that alter resistance to infection (5)
- protein calorie malnutrition
- pre-existing disease
- stress
- sleep deprivation
- exercise/physical conditioning
101
protein-calorie malnutrition
energy required for lymphocytes to divide into antibodies is insufficient
102
immunodeficiency disease
result from weak or impaired immune system: SCID, AIDS
103
Severe Combined Immunodeficiency Disease (SCID)
absence of both B and T cells (sometimes NK cells)
104
Acquired ImmunoDeficiency Syndrome (AIDS)
infects and kills T helper cells so the immune system can't produce antibodies or activate T cytotoxic cells
105
tissue grafts and organ transplant
MHC-I proteins on graft cells and MHC-II proteins on macrophages differ from recipient so they are targeted by T cells
106
drug used to avoid organ transplant rejection
cyclosporine: blocks cytokine production from T helper cells so there is no more signal for proliferation of T cells
107
transfusion reactions
hemolysis when erythrocytes are destroyed during blood transfusion
108
what acts as antigens in RBCs?
membrane proteins and carbohydrates on their surfaces
109
universal donor
O -
110
universal recipient
AB
111
blood group A has antibody...
anti-B
112
blood group B has antibody...
anti-A
113
blood group AB has antibody...
none (has A and B antigens on surface)
114
blood group O has antibody...
anti-A and anti-B (has no antigen on surface)
115
2 types of allergic reactions
- immediate hypersensitivity
- delayed hypersensitivity
116
anaphylaxis
mast cells release too much histamine in response to allergen, leading to hypotension and bronchiolar constriction, causing death
117
autoimmune disease
inappropriate immune attack triggered by body proteins acting as antigens
118
examples of autoimmune disease
- type 1 diabetes
- rheumatoid arthritis
- multiple sceloris
- myasthenia gravis: ion channels in muscle cells targeted
