week 6 - immunology Flashcards
1
Q
innate immunity
A
Barrier defences and molecular recognition of traits shared by a broad range of pathogens
2
Q
adaptive immunity
A
Specific recognition of pathogens through the use of receptors that recognise feature found on a particular part of a specific pathogen
3
Q
innate vs adaptive immunity
specific?
A
innate: no
adaptive: yes
4
Q
innate vs adaptive immunity
recognition of foreign substances
A
both: yes
5
Q
innate vs adaptive immunity
response upon frequent exposure
A
innate: same as first exposire
adaptive: faster and stronger following every exposure
6
Q
innate vs adaptive immunity
pathogen specificity
A
innate: recognises bacterial substance
adaptive: differentiates between bacterial species
7
Q
innate vs adaptive immunity
memory?
A
innate: no
adaptive: yes
8
Q
innate vs adaptive immunity
when is immunity acquried?
A
innate: present and unchanged from birth
adaptive: through lifetime depends on exposure
9
Q
innate immunity
aspects
A
- Physical barriers
o Prevent entry
o Remove substances - Internal: chemical mediators
o Prevent cell entry
o Cause inflammation
o Simulate adaptive immune response
10
Q
innate immunity
what defences does your body have to stop the entry of pathogens
A
- Skin
Mucus membranes (lining mouth, nose, eyelids) - Cillia (lungs) MUCUS
Sweep pathogens away - Stomach acid (pH)
- Sebaceous oils (pH)
- Sweat (pH)
- Pancreatic enzymes
- Urethra (protect bladder)
- Tears
Lysosomes - Saliva
Lysosomes - Shedding of intestine cells during peristalsis
- Inflammation
- blood
11
Q
innate immunity
what do antimicrobial substances do
A
discourage microbial growth
12
Q
innate immunity
antimicrobial substances
interferons
A
o Virus infected body cells
o Antiviral response reducing spread
o Stops virus infecting cells around it
o Stops replication
13
Q
innate immunity
antimicrobial substances
complement
A
o ~20 proteins work in cascade
Activates by surface proteins of microbes
o Results in bacterial lysis
o Marks bacteria for lysis via oponization
Coats antigens in opsins which helps binding of immune cells to pathogens
Mediates phagocytosis
- Iron-binding proteins
14
Q
innate immunity
antimicrobial substances
iron-binding proteins
A
o Restrict iron availability
o Restricts bacterial growth
15
Q
innate immunity
antimicrobial substances
A
o Broad spectrum-cidal activities
o Attract and mast cells
Affects lots of pathogens
This is the red flag that initiates the adaptive immune response
16
Q
innate immunity
chemical mediators can…
A
cause an inflammatory response
- Inflammation can be either local or systemic (throughout the body)
- Fever is a systemic inflammatory response triggered by substances released by macrophages in response to certain pathogens
- Septic shock is a life threatening condition caused by an overwhelming inflammatory response
trauma
–> pathogen enters tissue
–> tissue damage
–> stimlates release of chemical mediators
17
Q
innate immunity
chemical mediators
the release of histamine had 3 main things that it does
A
- Vasodilation
o Increase blood flow to area
o Brings more phagocytes and WBC to site
o More cells to the right area - Phagocytes
o Blood tissue
o Macrophages and neutrophils removes waste
o Dead pathogens, cell debris pus
o Involved in removing the waste and clearing the infection - Increased vascular permeability
o Fibrinogen and complement enter tissue from blood
o Fibrinogen fibrin to block area
o Spread of infection contained
18
Q
innate immunity
chemical mediators steps
A
- histamines and cytokines released, capillaries dilate
- antimicrobical peptides enter tissue, neutrophils are recruited
- neutriphils digest pathogens and cell debris, tissue heals
19
Q
innate immunity
what happens if the pathogen defeats the barrier defences ?
A
- Natural killer cells (NK cells)
- 5-10% of WBC population
- Spleen, lymph nodes, bone marrow
20
Q
innate immunity
what do natural killer cells do
A
NK cells target and cause destruction of infected host cells
main ways:
- Perforin channels cytolysis
- Granzymes induce self destruction
- Microbes could be intact phagoctosis
21
Q
innate immunity
cells involved in phagocytosis
A
neutrophils
macrophages
dendritic
eosinophils
NK cells
22
Q
innate immunity
cells involved in phagocytosis
neutrophils
A
o 1st response
o Increase inflammation
o Cidal pus
Neutrophils
In blood
Release chemical signals to increase inflamation
Have lysosomal activity so can start to have a cidial impact on infected cells
Produce the puss (kill your cell)
23
Q
innate immunity
cells involved in phagocytosis
macrophages
A
o Big eaters
o Wait in organs
o Clean up (after neutrophils)
24
Q
innate immunity
cells involved in phagocytosis
dendritic
A
o In tissues e.g. skin
o Stimulate adaptive immunity
o Generate antibody response
25
innate immunity
cells involved in phagocytosis
eosinophils
o Mucosal surfaces
o Defend against multicellular
o E.g. parastitic worms
26
innate immunity
cells involved in phagocytosis
NK cells
o Induces cell destruction
o Protect protiens from virus or cancer
o Release chemicals cause apoptosis
27
innate immunity
phagocytosis
steps
use receptors to recognise
1. chemotaxis
2. adherence
3. ingestion
4. digestioon
5. killing
28
innate immunity
phagocytosis
1. chemotaxis
- Chemicals attract phagocytes to site of damage
- Microbes, WBC, damaged tissue, activated complement proteins
29
innate immunity
phagocytosis
2. adhernece
- Phagocyte attaches to microbe/ non-self materials facilitated by bound complement proteins
30
innate immunity
phagocytosis
3. ingestion
- Pseudopod extends and surrounds microbe and fuses into a sac – phagosome
- Pseudopod that fuses into sac and surrounds microbes (phagosome)
31
innate immunity
phagocytosis
4. digestion
- Phagosome + lysosome phagolysosome
- Lysozyme breaks down microbe cell walls, other enzymes degrade nucleic acids, proteins etc. and oxidants involved in oxidative burst
32
innate immunity
phagocytosis
5. killing
- Microbe degraded
- Anything left over is kept in residual body
33
innate immunity
the lymphatic system
- Distributes lymph across body
- Drains excess interstitial fluid
- Transports dietary lipids
- Carries out immune responses
- Some macrophages reside in lymph nodes
- Dendritic cells migrate to lymph nodes after interacting with pathogens
o Stimulate adaptive immunity
Key for antibody activation
34
innate immunity
evasion of innate immunity by pathogens
- Some pathogens avoid destruction by modifying their surface to prevent recognition or by resisting breakdown following phagocytosis
- Tuberculosis (TB), one such disease, kills more than a million people per year
35
adaptive immunity
antibody mediated
how is it activated
antigens activate the adaptive immune system
- self: auto immune disease
e.g.rheumatoid arthritis
-nonself: microorganisms (e.g. bacteria, virus), allergens (e.g. pollen, dust mites, food)
36
adaptive immunity
antigens activate an...
antibody or cell mediated response
37
adaptive immunity
cell mediated
- Cytotoxic T cells
- Attack of infected cells
- Intracellular
o Relies on infected cells presenting antigens to cytotoxic T cells to elicit immune response to destroy the pathogen
- Bacteria, virus, fungi, some cancer, foreign tissue (transplant)
38
adaptive immunity
antibody mediated (humoral)
- Humoral (occurs in body fluids)
- B cells
- Plasma
- Secrete antibodies (INTERLEUKINS)
- Extracellular
- Bind antigens in fluid
o So don’t really need any cell presentation
39
adaptive immunity
antibody vs cell mediated
leucocyte involved
antibody: B cells
cell mediated: T cells
40
adaptive immunity
antibody vs cell mediated
attack pathogens
antibody: no
cell mediated: yes
41
adaptive immunity
antibody vs cell mediated
differentiate into plasma cells
antibody: yes
cell: no
42
adaptive immunity
antibody vs cell mediated
intra or extra cellular
antibody: extra
cell: intra
43
adaptive immunity
antibody vs cell mediated
secretes antibodies (interleukins)
antibody: yes
cell: no
44
adaptive immunity
antibody vs cell mediated
antigen recognition in...
antibody: fluid
cell: bacteria, virus, fungi, some cancer, non-self tissue
45
in adaptive immunity receptors provide...
pathogen-specific recognition
46
adaptive immunity
pathogen specific recognition
- The adaptive response relies on two types of lymphocytes or white blood cells
- Both B and T cells develop in primary lymphatic tissue
- Lymphocytes that mature in the thymus above the heart are called T cells
- Those that mature in bone marrow are called B cells
47
cells involved in adaptive immunity originate from...
stem cells in red bone marrow and mature else where
48
lymphatic system has an important role ini immune defence
- Thymus:
o Differentiation of lymphocyte stem cells into T-cells
- Lymph vessels:
o Transport phagocytes and lymphocytes around body (also pathogens)
- Secondary lymphatic organs e.g. lymph nodes and spleen:
o Home to many lymphocytes and macrophages
49
adaptive immunity
clonal selectioon
- Make copies of themselves after encounter with antigen
- Lymphocytes POLIFERATE (copy) and DIFFERENTIATE (specialise)
- All clones recognise the orginal antigen
- Increase numbers of specialsised cells
o So if encounters same antigen faster and larger response
- Occurs in secondary lymphatic organ
- Create effector and memory cells
50
antibody mediated (humoral) immune cells only circulate in...
lymphoid tissue
51
antibody immune response
steps
exta cellular antigens
-->active antibody production
plasma
--> antibody synthesis (specific)
memory
--> quick poliferation into memory and plasma for next time
52
classes of antibodies
(immunoglobulins)
- IgG
o Blood, lymph, intestines
o Enhances phagocytosis and triggers complement
- IgA
o Localised protection of mucous membranes against bacteria and viral infection
- IgM
o 1st class secreted on encounter with Ag
o Actives complement
- IgD
o B cell Ag receptors
- IgE
o Mast cells, basophils
o Allergy and hypersensitivity
53
antibody
structure
Antibodies have 4 polypeptide chains
- 2x heavy (~450aa)
- 2x light (~220aa)
hinge region is flexible
54
antibody mediated
how do b cells recognise antigens
B cells recognise antigens on the pathogen surface and are activated on binding with them
1) Bind
- Encounters antigen epitope:
o B cell activation
2) Antibody
- Secretion of antibody immunoglobulin (Ig)
o Same shape as original receptor)
3) Specific
- Bind to specific intact Ag in blood lymph
55
antibody mediated
once bound how to antibodies disable antigens
1. neutralise
2. immobilise
3. agglutinate and percipiate
4. activate complement
5. enhance phagocytosis
56
antibody mediated
once bound how to antibodies disable antigens
1. neutralise
the antibody combines to the virus binding sites to prevent the attachment to body cells or they can block or neutralize a bacterial toxin
57
antibody mediated
once bound how to antibodies disable antigens
2. immobalise
Antibody antigen binding on the cillia or the flagella of mobile bacteria and this might help reduce the mobility of bacteria so contains the spread of infection
58
antibody mediated
once bound how to antibodies disable antigens
3. agglutinate and precipitate
Because antibodies have two sites of binding and they can bind antigens from more than one pathogen can cause pathogens to clump together so phagocytes will more readily ingest these clumps because they are bigger and more drawn to them
59
antibody mediated
once bound how to antibodies disable antigens
4. activate complement
Complement work to enhance the inflammation and ultimately induce cell rupture so by attracting some of these 20 compliment proteins and it can basically cause the cell to rupture
60
antibody mediated
once bound how to antibodies disable antigens
5. enhance phagocytosis
Act as a flag to attract phagocytes following antigen binding
61
antibody-mediated response summary
eptiopes from antigen activate the...
adaptive immune response
62
antibody-mediated response summary
lymphocytes involved undergo...
clonal selection and response to a specific epitope
63
antibody-mediated response summary
B lymphocytes bind...
directly to antigens in the lymphatic system
64
antibody-mediated response summary
antigens can be...
disabled and antibodies against it are made
65
adaptive immunity
cell mediated response
steps
processed antigens activate
--> T cell production
effector
--> involved in destruction / deactivation of Ag
memory
--> quick proliferation into memory and effector cells for next time
66
adaptive immunity
cell mediated response
memory cells
Responsible for the lasting protection so next time the particular antigen is encountered again they can proliferate really quickly and differentiate into more memory cells and other effector cells
67
adaptive immunity
cell mediated response
effector cells
* Involved in the destruction and deactivation of antigens during the infection
68
adaptive immunity
cell mediated response
helper cells
* The intermediate between the t cell and b cell responses
* They can act on plasma cells to make more antibodies
* They act to attract cytotoxic t cells to the site of an infection
69
adaptive immunity
cell mediated response
cytotoxic t cells
* Involved in remembering what the antigen was and the destruction of the antigen during the infection
70
adaptive immunity
cell mediated response
supressor cells.
* Responsible for turning off the response
* Regulatory t cells (TREGs)
71
adaptive immunity
cell mediated response
antigens must be...
processed and presented before T cells can recognise them
72
adaptive immunity
cell mediated response
how are antigens processed and recognised
- Major Histocompatibility Complex (MHC) play a large role in this
o Antigen that mark cell as “self” to T cells
What problems might this cause?
o Class I: on all cells inserted into plasma membrane (except RBC)
o Class II: antigen presenting cells (e.g. B cells macrophages, dendritic cells)
73
adaptive immunity
cell mediated response
In infected cells the antigen is already inside the cell
--> endogenous processing with MHC I molecules to activate T cells to destroy the host cell
antigen inside cell
1. digestion of antigen into peptide fragments
2. synthesis of MHC I molecules
3. antigen peptide fragments bind to MHC I molecules
4. packaging of antigen MHC I molecules into a vesicle
5. vesicle undergoes excoystosis and antigen MHC I complexes are inserted into plasma membrane
- presented on cell surface (helps attract cytotoxic T cells)
74
adaptive immunity
cell mediated response
Antigen-presenting cells take in the antigens by endocytosis
--> exogenous processing to recruit immune cells
1. phagocytosis or endocytosis of antigen
2. digestion of antigen into peptide fragments
3. synthesis of MHC II molecules
4. pachaging of MHC II molecules into a vesicle
5. vesicles containing antigen peptide fragments and MGC II molecules fuse
6. antigen peptide fragments bind to MHC II molecules
7. vesicles undergoes exocytosis and antigen MHC II complexes are insetred into plasma membrane
- This helps recruit helper T cells to CD4 cell
75
adaptive immunity
cell mediated response
Antigen-presenting cells take in the antigens by endocytosis
--> enxogenous processing to recruit immune cells
Helper T cells (CD4) activate cytotoxic (CD8)
76
adaptive immunity
cell mediated response
summary
MHC I and II presentation leads to either the cell to be destroyed or the recruitment of more immune cells
77
adaptive immunity
cell mediated response
antigen recognition T cells
- Only bind fragments of antigens presented on host cell surfaces
- Recognises major histocompatibility complex (MHC) molecules
- After invasion of host cells, enzyme cleaves antigen antigen fragment
- Antigen fragment binds to MHC
- MHC migrates to cell surface to display
- T cell with matching specificity will bind
78
adaptive immunity
cell mediated response
structure of a T cell antigen receptor
- A lot more simple than B cell structure
- Straight rod shape with an alpha and beta chain with a di-sulphide bride linking the chains
- Constant region that’s stuck into the plasma membrane
- Variable region form antigen binding site
79
adaptive immunity
cell mediated response
after binding:
elimination of invaders
- activation
- elimination
- surveillance
80
adaptive immunity
cell mediated response
after binding: activation
cytotoxic T cells bind a specific antigen and require COSTIMULATION by IL-2 to activate before the cell is able to undergo clonal selection to form active cytotoxic T and memory cytotoxic T cells
- epitope recognised by T cell
- co-stimulation by IL-2 enablers CD8 to maintain coupling to infection body cell
leading to T cell activated
leading to memory T cells and active t cells
81
adaptive immunity
cell mediated response
after binding: elimination
cytotoxic T cells can induce apoptosis or cause the destruction of the host cell
Ag presented on infected cell surface matches cytotoxic T cell
- various chemicals release
1. granzymes - protein degraders responsible for indicing apoptosis in microbes
then phagocytosus
2. perforin - punches holes in the membrane - and gynylysin - creates holes in the microbe membrane.
82
adaptive immunity
cell mediated response
after binding: surveillance
memory cytotoxic T cells
- Memory B and T cell provide faster immune response on subsequent exposure (more cells)
o More cells for the response
- Quicker response upon subsequent exposure to antigen
- Why?
o More cells that recognise particular antigen
- Measure antibody titre (amount of antibody in serum)
- Depending on antigen
o Memory cells can remaining in body for decades
83
primary response
* B and t cells activates on the first encounter with an antigens
* Plasma cells release IgM and in the blood it travels around marking antigen displaying cells for destruction
Antibodies in plasma 5-10 days after exposure
After the primary response b will serve as memory cells and your memory b and t cells can trigger a secondary response
Antibodies in plasma 1-2 days after
And a longer lasting response
84
how is adaptive immunity acquired?
active
natural
- clinical disease, subclinical infection
artifical
- vaccine
85
how is adaptive immunity acquired?
passive
natural
- from mother
artifical
- immunogloblins (serum with antibodies)
86
naturally acquired active immunity
repeat exposure to antigen
recognition by B and T cells
costimulation
formation of antibody-secreting plasma cells, cytotoxic and memory T cells and memory B cells
87
naturally acquired passive immunity
IgG from mother to foetus across placenta
IgA from mother to baby during breast feeding
88
artifically acquried active immunity
antigens (non-pathogenic version) introduced via vaccination
cell mediated and antibody mediated responses stimulated
creation of memory cells
89
artificially acquired immunity
intravenous injection of antibodies
90
overview of immune system
innate
- recognises broad traits to indicate pathogen and not host
-initiates quickly
91
overview of immune system
innate
barrier
skin
mucous membranes
secretory
92
overview of immune system
innate
internal
lymphocytes
antimicrobial responses
inflammation
93
overview of immune system
adaptive
recognise specific traits
slow response
94
overview of immune system
adaptive
humoral (antibody mediated)
antibodies
in body fluids
95
overview of immune system
adaptive
cell mediated
cytotoxic
in body cells
