Revision immunity deck Flashcards

1
Q

GALT =?

A

Gut associated lymphoid tissue

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2
Q

Thymus =?

A

Thymus =?

Specialised primary lymphoid organ where T cells mature

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3
Q

Spleen does?

A

synthesises immunoglobulins and is reservoir continuing half the body monocytes

Makes dendritic cells and macrophages for the innate immune system

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4
Q

What is AID?

A

Beginning of original deck

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5
Q

Where do all immune cells originate from?

A

Hematopoietic stem cells in the bone marrow

Goes into the lymphoid lineage, melodic lineage or erythroid lineage

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6
Q

Serum = ?

A

Serum = ?

Plasma without clotting factors

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7
Q

Where is the immune system?

A

Where is the immune system?
In the lymphatics system and lymph organs

White blood cells circulate with blood

Some WBCs and quite a bit of plasma leave the capillaries in tissues

Circulation of plasma and WBC through interstitial space/tissues and back via lymphatics to lymph nodes allows surveillance of tissues for forge in molecules and pathogens

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8
Q

Describe neutrophils eosinophils and basophils?

A

Attack a variety of pathogens by phagocytosis or with antimicrobial or with anti-microbials and histamine released after degranulation

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9
Q

Describe plasma cells derived from B lymphocytes?

A

Secrete large amounts of antibody

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10
Q

Describe B and T lymphocytes?

A

Describe B and T lymphocytes?

Orchestrate the adaptive immune response and provide immunological memory

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11
Q

Describe monocytes and macrophages?

A

Phagocytes and regulate many aspects of innate and adaptive immunity

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12
Q

What does each pathogen have?

A

Antigens on its surface known as pathogen associated molecular patterns

Immune cells have invariant receptors on their surfaces known as pattern recognition receptors that recognise many of these PAMPS

Once a pathogen is recognised a cascade of events occurs activating an immune response to destroy it

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13
Q

Examples of PAMPs recognised by the innate system?

A

Cell wall components:
Peptidoglycan (bacteria)
Lipopolysaccharide (gram positive bacteria)
Galactomannans

Nucleic acid:
CpG motif DNA (bacteria)
ssRNA (viruses)
dsRNA (viruses)

Conserved surface proteins
Flagellin (bacteria)

Conserved stress proteins”
Heat shock proteins (bacteria)

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14
Q

Pattern recognition soluble receptors?

A
Pattern recognition soluble receptors?
Natural antibodies
Complement 
Pentraxins 
Collectins 
Ficolins
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15
Q

Pattern recognition cell receptors?

A

Toll-like-receptors
NOD-like receptors
RIG-like receptors
C-type lectin like receptors

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16
Q

Features of innate system?

A

Fast

Doesn’t require immunological memory

Activated by binding of PAMPS by PRRs on phagocytic cells

can discriminate self and non self

Receptors encoded in germline
Limited diversity

Typically recognise structures common to different microbes

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17
Q

Features of adaptive system?

A

Slower

Activated once the innate has been activated

Activated by a cascade of chemical signals from sites of infection , and physical interactions with phagocytic cells of the innate immune system known as dendritic cells that migrate from sites of infection into the lymphatic system to activate lymphocytes

Can discriminate self and non self

Receptors encoded by gene recombination - massive diversity

Typically recognise structures unique to different microbes

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18
Q

What decides the extent to how innate or adaptive system is used?

A

What decides the extent to how innate or adaptive system is used?
Severity, context and duration of disease, innate is mainly for something like a minor cut or splinter

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19
Q

What are cytokines and chemokines?

A

signalling molecules released at sites of infection by resident macrophages recruit neutrophils from the bloodstream leading to localised inflammation

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20
Q

Types of lymphocytes?

A

Types of lymphocytes?
All key in adaptive immunity

B-lymphocyte/Bcell - express antibodies as B cell receptors

Helper T lymphocytes

Cytotoxic T lymphocyte

Natural killer T cell

T-lymphocytes express T cell receptors

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21
Q

What happens with B and T cells during an adaptive response?

A

Have receptors specific for particular pathogen molecules proliferate

Clonal selection and expansion forms the basis of protective immunity and immunological memory through which the body is protected against future attack

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22
Q

Homeostasis in which specific molecular interactions keeps the immune system in check?

A

Antigen receptors and antigens

Cytokines/chemokines and their receptors
Cell-cell interactions

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23
Q

we get infected or colonised in?

A
Cytoplasm
Intracellular vesicles of cells 
Interstitial spaces 
Blood or lymph 
Epithelial cells
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24
Q

First barrier broken through during infection?

A

Skin

Cuts or burns

Main portals of entry is the mucosal epithelia of the gastrointestinal respiratory and urogenital tracts

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25
Describe immune cell differentiation?
Cells of the innate and adaptive immune systems are derived from the pluripotent hematopoietic stem cell The HSC divides to replace itself and produce a progenitor cell with the potential to give rise to all of the hematopoietic line ashes by generating further progenitor cells committed to progressively narrower ranges of differentiated fates
26
The erythroid lineage gives rise to?
erythrocytes and to megakaryocytic which shed fragments that form the platelets that initiate blood clotting
27
The myeloid lineage gives rise to?
Phagocytic and inflammatory cells of innate immunity
28
The lymphoid lineage gives rise to?
T and B cells of adaptive immunity and to natural killer (NK) cells which are specialised cytotoxic cells Killer cells count as innate as don't require activation
29
Hematopoietic stem cell lineages?
SCF = stem cell factor TPO =Thrombopoietin (platelet production) EPO = Erythropoietin (erythrocyte production)
30
What protects epithelial surfaces, especially the mucosa of the gastrointestinal, respiratory and urogenital tracts?
Basophils, mast cells and eosinophils Mast cells have a sentinel role, whilst basophils and eosinophils are circulating cells recruited from the bloodstream Whereas neutrophils destroy internalised micro organisms these cells typically provide immune defence against pathogens too large to be internalised On activation they release the contents of their cytotoxic granules to the exterior creating an environment hostile to an invading organism or directly killing it They also release histamines that mediate allergic and inflammatory responses such as coughing sneezing and vomiting These expulsive responses may be mechanisms that are evolved to expel parasites All 4 are known as the granulocytes
31
The phagocytic cells of the immune system comprise of?
neutrophils and macrophages which are effector cells, specialised to internalise and destroy micro organisms, and dendritic cells which internalise micro organisms for presentation to T lymphocytes of the adaptive immune system
32
Features of neutrophils?
Front line effector cells of innate immunity After differentiation they circulate for a few hours before entering tissues to engulf microorganisms and destroy them via microbicidal products stored in vesicles
33
Features of macrophages?
Long lived cells that provide immune surveillance They are derived from monocytes that circulate in the blood, differentiating as they leave the blood stream Like neutrophils they ingest and destroy micro organisms
34
Features of dendritic cells?
Are involved in the induction of adaptive immunity As immature cells they operate as phagocytes but rather than destroying the micro organisms they ingest their function is to display the ingested particles on their surface for recognition by T lymphocytes
35
Describe macrophage receptors?
Scavenger receptors - recognise particles released by dead or damaged tissues Complement receptors and antibody receptors Similar on dendritic cells
36
Activation of the innate immune system?
Directly through recognition of micro organisms or indirectly through recognition by cells of the adaptive immune system that then activate the innate immune defences This is done as a lymphocyte of the adaptive immune system produces antibodies whose variable regions recognise a surface component of the bacterium A non variable region of the antibody is then recognised by a receptor of the phagocyte which in turn is activated engulf it. In this way, bacteria that have masked the conserved components can be recognised and destroyed by the innate immune system
37
Whats opsonin?
A general term for soluble components of the immune system that coat micro organisms and stimulate uptake by phagocytes
38
2 ways phagocytes are pivotal role in the immune system?
On activation by microbial surfaces they release cytokines and chemokines that amplify the response to infection Cytokines and chemokines are signalling molecules. They increase the permeability of blood vessels and recruit additional cells and molecules of the immune system to sites of infection - the inflammatory response Hence they activate the adaptive immune response
39
What does the chemokines IL8 (CXCL8) do?
From a macrophage Recruits neutrophils, basophils and T cells to site of infection
40
Recruitment of neutrophils to inflammatory sites?
Fluid matrices contain antibacterial peptides and toxic proteins that are constitutively secreted and further induced in response to cell wall components such as lipopolysaccharide B-defensins in lung and skin a - defensives in paneth cells of the intestinal tract Lysozyme in fluids bathing the cornea Cathelicidins (another group of antimicrobial defensins) are produced by activated neutrophils and epithelial cells in addition to antimicrobial activity they trigger signaling through the formyl peptide receptor an innate immune recognition element thereby aiding recruitment of neutrophils to inflammatory sites
41
what are fMLPs?
powerful chemoattractants and activators of neutrophils Derived from BH2 terminal extensions of newly synthesised polypeptides fMLP directs the transport of secreted proteins the possess NH2 terminal signal peptides Cleaved by a signal peptidase following polypeptide transport and released into the extracellular space
42
What is chemotaxis?
neutrophils are attracted to bacterial chemical products like the peptide fMLP
43
Describe the inflammatory response?
Memory T cells monitor keep the tissues of the body under surveillance If they detect no antigen they return to circulation via the lymphatic system If there is an antigen it is processed by antigen presenting cell, and presented as MHC peptide complexes This activates memory T cells Which release cytokines such as TNF-a which act on local blood vessels TNF-a activates the vascular endothelium Loosens gaps in them so more blood leaks out, swelling occurs and looks more red due to RBC The activated endothelium also releases adhesion molecules that allows phagocytes out the blood vessel Takes 1-3 days The phagocytes uptake the antigen and also can present it Memory and effector T cells also leave the vessel
44
Describe cytokine signalling?
go on original deck Cytokine receptor consist of 2 chains Each having an extracellular binding domain An a intracellular binding domain which has JAKs kinases on Without cytokines these 2 receptors are not associated Cytokines stabilise the heterodimer bringing them together, including the 2 JAK kinases The JAK kinases can then phosphorylate the cytoplasmic tails STAT molecules then bind to the chains at the bottom of the receptors which get phosphorylated by the JAKs The STAT molecules can now dimerise and migrate into the nucleus where they can directly activate gene transcription
45
Describe rolling adhesion?
Get from original deck Blood vessel endothelium at sites of infection expresses selectin molecules (P-selectin and E-selectin) the selectins are triggered by cytokines released by sites of inflammation Leukocytes such as neutrophils express the ligand for these selections in the form os s-Lex These creates a weak bond with the selectins and the neutrophils rolls along the blood vessel forming and breaking bonds These neutrophils will find somewhere they can squeeze for the endothelial cells out of the blood vessel Only happens in veins
46
What are the first responders to tissue detected microbes?
Neutrophils
47
What are the types of secreted molecules released by
In general deck Lysozyme - released in fluids of cornea, saliva and gut (Paneth cells) Breaks down peptidoglycan, a component of the bacterial cell wall Phospholipase A2 - breaks down phospholipids in cell membrane of bacteria Antimicrobial peptides - Defensins - (alpha-defensins in Paneth cells of the intestinal tract and beta-defensins in lung and skin) – disturb the cell membrane of bacteria and fungi Cathelicidins (another group of antimicrobial defensins) are produced by activated neutrophils and epithelial cells Histatins (oral cavity, active against fungi) Lecticidins (creates a pore in microbial cell membranes) Complement: exists in fluids and blood: capable of direct killing of pathogens through membrane attack complex (MAC) also potentiates phagocytosis and the recruitment of other inflammatory mediators
48
More details on complement?
Small proteins that are synthesised by the liver, tissue macrophages, blood monocytes and epithelial cells of the genitourinary system and gastrointestinal tract They circulate the blood as inactive precursors Can diffuse into tissues Capable of direct killing of pathogens through membrane attack complex Potentiaites phagocytosis Potentiates the recruitment of other inflammatory mediators
49
What's the complement cascade
Is a part of the immune system that enhances (complements) the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism, promote inflammation, and attack the pathogen's cell membrane. Its spontaneous and low level activation If deposited onto pathogen = activation If deposited into host cell = inhibited
50
What does C3 convertase do?
Cleaves C5 into: C5a: potent anaphylotoxin C5b: initiates Membrane attack complex
51
What is the membrane attack complex?
or terminal complement complex (TCC) is a structure typically formed on the surface of pathogen cell membranes as a result of the activation of the host's complement system, and as such is one of the effector proteins of the immune system. In order to permeabilize both the bacterial outer and inner membrane and thus kill a bacterium, The MAC is much more active towards Gram-negative than gram positive bacteria Ion influx and efflux causes the cell to lyse
52
Where does phagocytosis occur?
Phagocytosis occurs mostly in neutrophils and in monocytes/macrophages/dendritic cells
53
What is phagosome killing?
The phagolysosome is matured through sequential fusion with endosomes and lysosomes and becomes a very specialised intracellular compartment The bug is digested and degraded Unpleasant environment for microbes
54
How does phagocytosis occur?
Microbes are recognised by phagocytic surface receptors: 1. PAMPS-PRR (Toll-likereceptors, C-type lectins, scavenger receptors) 2. Opsonization Microbe coated with complement = binds CR3-CR4 Microbe coated with antibody = antibody binds FcRecepors Recognition and subsequent signalling trigger phagocytosis
55
Describe how the phagolysosome is matured from a phagosome
The phagolysosome is matured through sequential maturation with lysosomes and becomes a very specialized intracellular compartment with: More details on original flashcard 67
56
What's nutritional immunity?
When for example the phagasome pumps out iron which the microbe needs to live for nutrition
57
How is the phagosome adapted in dendritic cells?
To perform antigen presentation, to degrade antigens and load them to bridge adaptive immunity
58
Extracellular killing?
Eosinophils (toxic granules): They release mitochondrial DNA against bacteria ``` They also release granules are active against parasites, such as: major basic protein (MBP) eosinophil cationic protein (ECP) eosinophil peroxidase (EPX) eosinophil-derived neurotoxin (EDN) ``` Neutrophil extracellular traps (NETS) are also used catch microbes in sticky DNA fibrils
59
When killing a microbe is not possible what can happen?
Granuloma can contain microbes Coordinated response of TH1 T-cells and macrophages which creates a layer of macrophages and outer layer of T cells which walls off the pathogen Important in tuberculosis and in certain parasite infections Means we can co live with the parasite
60
What organ is first to encounter blood after the gut?
The liver, gets rid of bad bacteria This is done by liver macrophages called Kupffer cells using CRig functions as a pattern recognition receptor on Kupffer cells to directly bind gram positive bacteria
61
How is host damage regulated/prevented?
If its chronic can cause a degenerative or auto immune disease This is prevented by: Host cells have mechanisms to prevent activation of innate immune killing Intracellular signalling cascades triggered by PAMPS and DAMPS direct the magnitude and nature of the immune response in a tissue specific manner
62
When the immune system is de regulated?
CYTOKINE STORMS, IMMUNE-MEDIATED DAMAGE, ALERGY, FIBROSIS
63
Overview of immune memory?
The adaptive immune system consist of T and B lymphocytes The T lymphocytes and immunoglobulins, and antibodies that B-lymphocytes produce can recognise an unlimited number of different targets Become effective only after a delay of 2 to 4 days on first encounter Lymphocytes and lymphocyte products specific for a given organism then persist as immune memory and are rapidly protective on re-exposure to the same infectious agent This property of the adaptive immune system forms the basis of the protective effects of vaccination
64
What does vaccination do?
What does vaccination do? The ability of the body to remember an infectious agent to which it has been exposed is the basis for natural and artificial immunity against a disease Vaccination initiates a primary immune response, generating memory cells without making the person ill Later, if the same or very similar pathogens invade the body, specific memory cells already exist They recognise the agent and produce massive number of lymphocytes and immunoglobulins that overwhelm the invaders
65
Specific functions of each cell in adaptive immunity?
Adaptive immune responses are mediated by lymphocytes of the lymphoid lineage which fall into two major classes: T lymphocytes - kill virus-infected and cancerous cells (CD8+ T cells/cytotoxic T lymphocytes or CTLs or, activate other cells of the immune system (CD4+ helper T cells) B lymphocytes - secrete immunoglobulins Natural killer cells -capable of killing virus-infected or cancer cells immediately without prior activation and without clonal expansion They are generally regarded as part of the innate immune system (because they don’t require prior activation) Activation occurs via binding of activating receptors to surface molecules produced by cell damage e.g. cancer or that are encoded by infecting viruses
66
Describe lymphoid lineage - cellular differentiation?
Mature lymphocytes that have not yet encountered antigen are known as naïve lymphocytes Differentiation into effector cells is stimulated by encounter with antigen and is preceded with a vigorous proliferation that selectively expands the numbers of those lymphocytes with receptors specific for the inducing antigen This is known as clonal selection of antigen- specific lymphocytes
67
Describe the lymphatic system?
The critical interactions between activated dendritic cells and lymphocytes occurs in lymphoid tissues Lymphocytes enter lymphoid tissues from the bloodstream Return to the bloodstream through the lymph if they are not activated ``` Migration through lymphoid tissues, and cellular interactions, are guided and controlled by adhesive cell surface molecules whose expression is regulated by cytokines and chemokines ```
68
How do T lymphocytes recognise antigens?
``` How do T lymphocytes recognise antigens? T lymphocytes recognise antigens by means of T cell receptors generated during their differentiation - they interact with APCs (antigen- presenting cells - DC, macrophages and B cells) via complementary ligands ``` Each individual lymphocyte expresses an antigen receptor of only one specificity, but the total population of lymphocytes in any given individual is collectively capable of recognising virtually any antigen
69
Features of the T cells CD4?
Marker of helper T cells Is a co receptor for MHC call II molecules These co-receptors play an important part in signal tranduction on antigen binding by T cells
70
Features of CD8 T cells?
Marker of cytotoxic T cells Co receptor for MHC call I molecules These co-receptors play an important part in signal tranduction on antigen binding by T cells
71
Features of dendritic cells?
Dendritic cells of the innate immune system play a crucial role in activating adaptive immunity Begin life as phagocytes but when activated by conserved components of micro-organisms, or by inflammatory cytokines released by macrophages, become dedicated to displaying components of ingested micro-organisms for recognition by naïve T lymphocytes and subsequent differentiation of naïve T lymphocytes into effector T cells Especially numerous in epithelia and at mucosal surfaces In mucosal epithelium of the gut, dendritic cells are concentrated at specialised sites of antigen collection that overlie lymphoid tissues Some have specialised surface properties that enable them to extend their long dendritic processes between the cells of the epithelium and into the lumen to sample antigens These cells are directly exposed to ingested antigens and to commensal bacteria as well as invading pathogens These cells have a specialised role in preventing inflammatory responses to harmless gut residents
72
M cells do what?
deliver antigen from the lumen of the gut to the underlying tissue where dendritic cells cluster
73
Describe how the dendritic cells activates the adaptive immune system?
Describe how the dendritic cells activates the adaptive immune system? A dendritic cell displays a component of a micro-organism for recognition by a T lymphocyte bearing a receptor for that component. This stimulates it to proliferate and differentiate into an effector cell. When the effector cell recognises the same antigen displayed on the surface of a B lymphocyte, the T cell activates the B lymphocyte, which in turn proliferates and secretes antibodies that recognise the micro-organism
74
Describe T cell targeting?
Unlike B cells whose surface immunoglobulin molecules are adapted to serve as antigen receptors, T cells are unable to interact directly with intact antigen and so must interact with other cells of the immune system T cells are focused on their target cells by cell surface proteins known as MHC molecules because they are encoded in the major histocompatibility complex (MHC) MHC molecules carry fragments of antigen, usually peptide fragments of proteins, from internal compartments of the target cell to the cell surface and display them for recognition by the T cell All naïve T cells are activated by antigen fragments displayed on MHC molecules on the surface of dendritic cells, and after differentiation into effector cells they are triggered to kill or activate cells displaying the same complex of MHC and antigen
75
Whats the Major histocompatibility complex?
Whats the Major histocompatibility complex? Chromosomal region containing genes that encode cell surface proteins that regulate interactions among cells of the immune system During transplant the more similar they are the longer it will take for the body to reject the new organ There is class I molecules (Activate CD8 T cell) and class II molecules (Activate CD4 T cell) These monitor different internal compartments of cells and are recognised bu distinct classes of T cells
76
2 internal compartments of cells that need to be monitored for pathogens?
2 internal compartments of cells that need to be monitored for pathogens? The cytoplasm All viruses and some important bacterial pathogens replicate in the cytoplasm Vesicles of the endosomal/lysosomal pathway Contain internalised antigens derived from extracellular pathogens In the specialised case of macrophages, vesicles may harbour bacteria and some fungi (e.g. Cryptococcus) adapted to survive phagocytosis The cytoplasm is monitored by MHC class I molecules Vesicular compartments are monitored by MHC class II molecules
77
Features of MHC class I molecules?
MHC class I molecules are expressed on all nucleated cells (not RBC) including APCs and bind peptides generated by cytoplasmic proteases from cytoplasmic proteins Their critical role is to display antigens derived from pathogens that replicate in the cytoplasm, and antigen displayed on MHC class I molecules is recognised by cytotoxic T cells, which kill the infected cells This system ensures the destruction of cells in which cytoplasmic pathogens are replicating and is believed to be essential for the elimination of some of these pathogens
78
Describe recognition of antigen and MHC class I molecules by cytotoxic T cells?
``` Peptide fragments of pathogens, such as viruses, that replicate in the cytoplasm compartments of cells are carried to the cell surface by MHC class I molecules and are recognised by cytotoxic T cells forming an immune-synapse, outer ring is an adhesion ring and the inner is a signalling zone and secretory zone ``` Upon activation, CD8 T cells produce: 1. Perforins - proteins that form pores in the membrane of target cells 2. Granzymes - proteases that induce programmed cell death on entry into target cells
79
Describe MHC class II molecules?
MHC class II molecules are normally expressed only on cells of the immune system, and in particular on professional APCs (B cells, macrophages and dendritic cells) They bind to peptides generated from internalised antigen in the endosomal compartments of cells Antigen derived from internalised micro-organisms by lysosomal proteases and displayed by MHC class II molecules on dendritic cells is recognised by naïve T helper cells at the initiation of immune responses
80
MHC class II processing?
get from main deck The 2 chains of it form in the endoplasmic reticulum An invariant chains binds to the peptide grove formed by the 2 chains Preventing unwanted peptides in the ER from binding The invariant chains takes it through the ER and Golgi apparatus via a vesicle Proteases are released inside the vesicle cleaving the invariant chain in 2 places leaving the CLIP peptide bound to the MHC class II molecule Engulfed proteins or pathogens that are degaded in the vesicle can't mind on to MHC class II as it's blocked by CLIP HLADM allows the CLIP to be removed, its present in the vesicle and acts as a catalyst The pathogen peptides can now bind and the vesicle is taken to the cell surface to present as as an antigen
81
Naive helper T cells are first activated when?
They recognise antigen bound by MHC class II molecules on the surface of dendritic cells
82
Recognition of antigen and MHC class II molecules on macrophages by helper T cells?
``` Helper T cells recognise fragments of a pathogen that has been internalised by macrophages and have undergone proteolytic digestion to generate fragments that are carried to the cell surface by MHC class II molecules. ``` The helper cell is then stimulated to activate the macrophage to destroy the internalised pathogen. This is particularly important for defense against bacteria that are able to grow in the internal vesicles of macrophages Helper T cell tells the macrophage via cytokines that what its doing is correct
83
Recognition of antigen and MHC class II molecules on B cells by helper T cells?
``` B cells internalise antigens bound to their surface immunoglobulin and deliver them to the endosomal compartments of the cell where they are digested into fragments. The antigen fragments then bind to MHC class II molecules which carry them to the cell surface where they are recognised by helper T cells, which then activate the B cell to proliferate and differentiate into an antibody- secreting plasma cell ```
84
What is CD4 or CD8?
Coreceptor from Tcell receptor binding to MHC
85
CD4+ T cell subsets?
CD4+ T cell subsets? | There is TH1 and TH2 which release different cytokines which have different effects (picture in folder)
86
What do co-stimulator pairs do?
Enhance and sustain signal delivered by the MHC-antigen T cell receptor interaction (photo in folder)
87
Co-stimulator pair activation?
Co-stimulator pair activation? Professional antigen presenting cells present either MHC moelcules and co stimulator molecules such as CD80(B7.1) When a complex is formed with the T cell signals are sent both ways, it tells the antigen presenting cell to produce more co stimulator pairs, and the T cell is induced to form pairs for the new co-stimulator pairs which can then form ligand making the connection stronger with the T cell This then stimulates another co stimulator that is required when bound for full activation of the T cell
88
Summary of the immune response?
Might be more important to learn this rather than all the subsets Pathogens manages to get through first layer of skin (through epidermis into dermis) The bacteria establish an infection here Phagocytic cells such as neutrophils and macrophages engulf the pathogen Dendritic cells engulf as well and are stimulated by binding pathogens to leave the site of infection and migrate to a lmpyh vessel where the are drained into a lymph node In the lymph node T cells are activated by the antigen presented on the dendritic cells and in turn activate B cells to release antibody Effector T cells and antibody return to circulation They return to the site of infection as inflammatory mediators have caused changes in the blood vessel endothelium CD4 T cells activate macrophages to become more cytotoxic antibody recruits complements of lysed bacteria directly and to opsonise them by inducing there uptake by phagocytes In the case of a virus activated CD8 cells would kill any infected cells present
89
What does opsonise mean?
More susceptible to uptake by phagocytosis
90
What are antibody molecules?
Host proteins produced in response to the presence of foreign molecules in the body Synthesised primarily by plasma cells (lymphoid lineage) and are components of the adaptive immune system Circulate throughout the blood and lymph where they bind to foreign antigens Antibody-antigen complexes are removed from circulation primarily through phagocytosis by macrophages
91
Describe clonal selection of antigen specific lymphocytes?
The lymphocytes of any individual collectively express a large number of different receptors Some cells bear receptors that recognise self-antigens. While still immature, they are eliminated This process of clonal deletion is a critical mechanism for ensuring self-tolerance Once mature, lymphocytes activated by recognition of foreign antigen differentiate into effector or memory cells through a process of clonal expansion This is the mechanism for antigen-specific immune responses and immune memory
92
Receptor editing and clonal deletion of developing B cells?
Receptor editing and clonal deletion of developing B cells? The mechanism through which self-tolerance is established differs between T cells and B cells An immature B cell in the bone marrow expresses membrane Ig antibody together with Iga and Igb chains as the B cell receptor If the BCR in is engaged by self antigens present in its local environment, maturation of the B cell is arrested and it stays in the bone marrow Re-arrangement and recombination of genes encoding the BCR results in a new BCR possessing the original heavy chain but new light chain This process is known as receptor editing If the B cell is no longer auto-reactive, then it is exported to the periphery If this BCR is still auto-reactive, then it can try again for a limited time before dying (clonal deletion)
93
Induction of B cell antibody response by T cells?
Get from main deck Germinal centres where B cells proliferate and undergo isotope switching hyper mutation Germinal centres form from dendritic cells having antibody on their surface activating antigen specific CD4 T cells which proliferate into effector cells capable of activating antigen specific B cells Once activated it proliferates to form a primary focus for antigen specific B cells B cells from the primary focus migrate to nearby follicles whilst other B cells stay in the local area secreting antibody B cells that enter to follicle proceed to proliferate rapidly under this time they also undergo somatic mutation to introduce new variation into the B cell receptor The receptors are tested with their ability to bind to antigen those that fail to compete die
94
Antibody structure
Large family of glycoproteins Share key structural and functional features Functional - able to bind both to antigens and to specialised cells or proteins of the immune system Structural - composed of one or more copies of a characteristic unit that form a Y shape So any molecules or parts of molecules recognised by the variable antigen receptors of lymphocytes are known as antigens
95
Whats the epitope (antigenic determinant)?
The specific region of the antigen bound by the variable region of an immunoglobulin
96
What's the paratope?
The antigen binding region of an antibody
97
What's affinity?
Affinity is the measure of the strength of the binding of an antigen by an antibody Antibody binding to antigen is non-covalent and reversible The affinity of an antibody (Ab) for an antigen (Ag) is related to the ratio of the rates of the forward reaction for formation of the complex to back reaction for decay of the complex Like a reversible reaction in chemistry A level
98
Papain cleavage on antibody?
Papain cleavage on antibody? Fab 1 Fab 11 Intact Fc 111
99
pepsin cleavage on antibody?
pepsin cleavage on antibody? F(ab)2 Fc fragments
100
Antibody structure - the Y shape?
Antibody structure - the Y shape? Heavy chain is top part of arm of Y Light chain is lower part of arm of Y Each Y contains four polypeptides Two identical heavy chains (55kDa each) Two identical light chains (22kDa each) The four polypeptide chains are held together by disulphide bridges and non-covalent bonds The two domains that carry the antigen binding sites are known as Fab fragments (fragment having the antigen binding site) (the 2 arms) (antigen binds at the end of the arm) The third domain is known as the Fc fragment (the fragment that crystallizes) (the base) Hinge region in the middle of the arms aids movement ``` The ability to bind antigen is determined by the N-terminal domains. These differ considerably between antibodies of differing specificities and are therefore termed ‘variable’ or ‘V’ domains - the end bits of each of the arms ``` Top part of the base of the Y is where complement binding happens Bottom bit of the base of the Y is where binding to Fc receptors happens
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What is hyper variability?
``` VH is top bit of the top arm of the Y, VL is the bottom bit of the top of the Y arm Sequence analysis of amino acids of VH and VL regions reveals small regions of hyper-variability within four conserved framework regions (FR1, FR2, FR3 and FR4) ``` In the 3-dimensional structure, the hyper-variable regions form loops that combine together to form the principal antigen-binding surfaces These surfaces are called the complementarity determining regions or CDRs (CDR1, CDR2 and CDR3)
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Classes of immunoglobulin (different name for an antibody) Get Me An Edo Dad
There are five main classes of antibody in serum IgG, IgM, IgA, IgE and IgD The five classes are divided on the basis of the number of Y-like units and the type of heavy chain polypeptide they contain (y, u, a, e and delta ) Greek symbols and associate same order as ones above While there are five different types of heavy chains, there are only two light chains (k or L) Greek again One light chain always associates with one heavy chain, so the number of light chains always equals the number of heavy chains There's 2 heavy chains and 2 light chains per antibody
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antibody in humans?
In humans, the IgG class has four sub-classes (G = gamma) IgG1, IgG2, IgG3 and IgG4 These have y1, y2, y3 and y4 heavy chains The IgA class has two sub-classes IgA1 and IgA2 These have a1 and a2 chains respectively
104
What's a J chain?
Holds more than 1 antibody together
105
What's a secretory component?
In double antibodys
106
Movement of antibodies across mucosal tissues with secretory IgA? And what are ITAMs
is flashcard 126 complex probably don't need to know | and 127 and 128
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Antibody-mediated cytotoxicity?
The two most widely recognised mechanisms of antibody- mediated toxicity are: 1. Antibody-dependent cell-mediated cytotoxicity (ADCC) Antibody attracts cytotoxic cells by means of their Fc receptors 2. Complement-mediated cytotoxicity (CMC) Antibody binding results in the fixation of complement onto the target cell
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Opsonisation and phagocytosis process?
It requires triggering of specific receptors on the phagocyte Fc receptors that bind antibody coated bacteria are one of the receptors capable of triggering phagocytosis engulfing it and forming a phagosome Lysosomes move in to degrade the content in the phagosome
109
What is complement?
What is complement? The complement system, also known as complement, consists of about 30 serum and membrane proteins that can mediate a variety of immune reactions including: Triggering inflammatory responses Attraction of phagocytes to sites of inflammation Degradation of membranes or virus envelopes Stimulation of antibody production
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Activation of complement?
Activation of complement? The active components of complement are generated from inactive precursors by a cascade of proteolytic reactions These are triggered through 3 different pathways: The LECTIN pathway (recognition of carbohydrate moieties e.g. by collectins such as mannose-binding lectin) 2. The CLASSICAL pathway (antibody binding to antigen in immune complexes) The ALTERNATIVE pathway (directly at microbial cell surfaces) Activation of complement by any one of the pathways initiates a cascade of cleavages in which each component in the pathway is cleaved into two fragments: The small fragment (a fragment) The big fragment (b fragment) The b fragment forms a subunit of the protease complex mediating the next cleavage in the pathway The reactions can be divided into early events, in which the components are not the same for the same three pathways and late events, in which they are identical
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Early and late events of complement formation?
In main deck The function of the early events is to generate two functionally equivalent forms of a protease, known as C3 convertase C3 convertase then initiates the late events to produce the effector components of complement C3 convertase covalently attaches to the cell surface at which the complement activation was initiated Cleavage of complement component C3 leads to effector activation In this way, the effects of complement activation are confined to the infectious organism that triggered
112
Pentraxins =?
Pentraxins = Pentameric serum proteins that participate in innate immunity and can also activate the Classical pathway of complement Steps of this on flashcard 134
113
What are collections and ficolins?
In Main deck The epithelium of the respiratory tract is lubricated by a layer of phospholipids and proteins known as surfactants ``` Two of these, Surfactant Protein-A (SP-A) and Surfactant Protein-D (SP-D) are Collectins and function as opsonins, coating microorganisms (e.g. Pneumocystis in AIDs patients - Lecture 8) and stimulating uptake by phagocytes ``` The Collectin family also includes Mannose-Binding Lectin (MBL) - binds to mannose-containing carbohydrates on surface of viruses, bacteria and fungi More details of their mechanism on 135
114
Lectin pathway details?
On card 136
115
Alternative pathway?
on card 137
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C3a, C5a functions?
C3a, C5a functions? | peptide mediators of inflammation, phagocyte recruitment
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C3b function?
Binds to complement receptors on phagocytes Opsonization of pathogens Removal of immune complexes Equation on card 139
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What is hypersensitivity?
Undesirable reactions produced by the 'normal' immune response Can be an allergy or auto-immunity allergy = reacting to something not normally in the body Auto-immunity - reacting to stuff in our body
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Different types of hypersensitivity reactions?
On 141
120
Allergy =?
Excessive immune responses to harmless antigens (allergens) - Most allergic reactions are due to IgE-mediated responses
121
Why can dendritic cells sample luminal antigens through the epithelial cells?
Can express tight junction proteins allowing interaction with epithelium Epithelial cells can secrete factors that trigger DC activation: Instructive cytokines DAMPS - damage associated molecular pattern
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Effector mechanisms in IgE mediated allergy?
Get from main deck Mast cells: abundant in mucosal tissues (lung, gut) and connective tissues (e.g. surrounding blood vessels) Th2 tells B cell via Type 2 cytokines (IL - 4, IL - 5, IL - 13)to class switch IgE antibody, which forms plasma cells which take the antibody to the Fc receptors on mast cells that causes degranulation when stimulated by the allergen Most IgE is cell bound (on FcεR) not in body fluids (unlike other antibodies)
123
If a question on allergy mechanisms comes up =
149 to 155
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Indirect recognition of bacteria by phagocytes?
bacteria coated with antibodies are recognised by antibody receptors (Fc receptors) Bactiera coated with C3b are recognised by C3b receptors
125
Direct recognition of pathogen associated molecular patterns?
PAMPS are recognised Pattern recognition receptors such as Toll-like receptor
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Structure of a toll like receptor?
Extracellular domain - ligand recognition Intracellular domain - signalling (dimerisation is essential for signalling) so TL1/2 would be a heterodimer and TL5/5 would be homodimer
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Consequences of TLR recognition by phagocytes?
Activation of phagocytes which leads to: Cytokine and chemokine production Ingestion and killing
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MHC presentational pathways?
Protein within the cytosol: Processed by the proteasome generates peptides Go to endoplasmic reticulum where become processed with MHC class 1 to form a complex which is recognises by CD8+ T cells Activated CD8 T cels kill host cells infected with bacteria by releasing cytotoxins such as perforin, granzymes and granulysin ``` Protein taken up into the phagosome: Endocytosis of extracellular protein in it's vesicle it forms a complex with with MHC class 11 from the ER, this complex is presented on the cell surface and recognised by CD4+ T cells ``` CD4+ T cells releases different cytokines that result in inflammation, macrophage activation, antibody response
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What's agglutination?
Clumps the bacteria so cleared better by phagocytes Its triggered by antibodies
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What's complement binding?
Antibodies bound to bacteria promote complement binding and complement activation by the classical pathway Complement can now effect them
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GP encodes?
In main deck GP encodes Ebola virus glycoprotein (GP). Two forms: 1. Trimeric trans-membrane complex targets virus to cells via receptor binding - allows virus to introduce its contents into monocytes/macrophages leading to inflammatory cytokine dysregulation 2. Soluble dimeric form (sGP) secreted after infection – prevents neutrophil activation
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Virus breaking and entering?
Like bacteria, viruses must overcome epithelial barriers of skin and mucosa to establish infection Intestinal viruses e.g. poliovirus enter via antigen-sampling M cells Respiratory viruses e.g. influenza virus and rhinoviruses establish infection in the epithelial cells of the airways Some viruses e.g. Zika, Dengue and West Nile viruses require insect vectors for transmission Bloodborne viruses e.g. HIV and hepatitis B can invade through mucosa or epithelia following physical trauma
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Virus immunity?
Major innate immunity is mediated via type 1 interferons*, complement and natural killer (NK) cells Major adaptive immunity is mediated via antibody and cytotoxic T lymphocytes (CTLs) Interferons are Group of proteins that induce host cell enzymes that affect transcription and translation of viral genes
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Adaptive immune response to acute virus infection?
Adaptive immune response to acute virus infection? Appearance of virus is followed rapidly by a massive expansion of virus-specific CD8 T cells CD4 T cell expansion and contraction also occurs but at a lower magnitude Neutralising antibodies are produced relatively early after acute infection with cytolytic viruses
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What do neutralising antibodies do?
Prevent viruses leaving and entering cells
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Features of aids?
Acquired Immune Deficiency Syndrome (AIDS) is caused by the Human Immunodeficiency Virus (HIV) HIV infects and destroys CD4+ T cells
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HIV epithelial entry?
HIV-1 can cross mucosal surfaces through M cells - prevalent in tonsils and rectal epithelia It can also gain access via epithelia damaged by ulcerative infections, or by trauma or injection (i.v. drug use or blood transfusion) Vaginal epithelia lack M cells - HIV gains access via interdigitating processes on Langerhans cells Epithelial cells in the small intestine express CCR5, a chemokine receptor HIV-1 binds to CCR5 (once tethered by galactosylceramide) via the viral envelope glycoprotein gp120 and the virus is transcytosed
138
HIV getting into lymph nodes and CD4 T cell and infection cycle and infection cycle and immunological consequences
191, 192, 192, 193, 194
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Features of influenza A?
Influenza A is a spherical or rod- shaped enveloped virus covered with 2 spike-like glycoproteins: Trimeric hemagglutinin (HA) Tetrameric neuraminidase (NA) HA mediates binding to cell surfaces and internalisation NA cleaves sialic acid and promotes viral release from cells
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Immune response to infleunza virus infection?
Antibody mediated immunity: Can bind to HA and block viral attachment Can also bind to NA protein and prevent release of new virions ``` Cell mediated immunity: CD8 T cells recognise the infected cell due to its MHC class 1 the T cell then causes cell lysis ```
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What's antigenic shift and antigenic drift?
What's antigenic shift and antigenic drift? Epidemics occur when point mutations (red dots) accumulate in surface HA (ovals) or NA (diamonds) This leads to ANTIGENIC DRIFT so that, in many previously immune individuals, HA and NA are no longer recognised by neutralizing antibodies produced in response to earlier infections Pandemics occur when avian influenza viruses and human influenza viruses infect pigs and re-assortment of the two genomes leads to the expression of avian HA or NA in a virus otherwise adapted to infect humans (ANTIGENIC SHIFT)
142
mycosis = ?
Fungal infection of humans
143
Host recognition of fungal infection?
in the main deck: Innate recognition of fungi is mediated by interactions with conserved cell wall constituents (glucans, mannans, galactans). PRR Dectin-1 (gene is CLEC7A) is highly expressed on the surface of dendritic cells and in lesser amounts on macrophages It has a C-type lectin carbohydrate recognition domain that mediates the recognition of beta 1,3- and 1,6-linked glucans on the surface of intact cells and zymosan (zymosan=cell wall fragments consisting of beta-glucans, mannans, mannoproteins and chitin) So Dectin-1 is essential for immune system Engagement of Dectin-1 results in tyrosine phosporylation of its cytoplasmic immunoreceptor tyrosine-based activation motif (ITAM) Syk (Il-10) and others (TNFalpha is Syk-independent) Dectin-1 acts synergistically with TLRs to induce production of inflammatory cytokines and the production of reactive oxygen species (ROS)
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What are toll like receptors?
Dendritic cells and other immune cells must be able to distinguish between apoptotic particles generated by normal tissue turnover and particles that are indicative of infection The molecules mostly responsible for making this pivotal distinction are those of the family of Toll-like receptors (TLRs) Stimulation of immune cells through their TLRs leads to synthesis and secretion of proinflammatory cytokines, thereby initiating the inflammatory response that recruits both soluble immune components and immune cells from the blood TLR stimulation of dendritic cells also induces the initiation of an adaptive immune response Acts synergistically with TLRs
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Features of Mannose-binding lectin (MBL) and complement?
In the main deck: Candida expresses surface adhesins and mannoproteins that activate the alternative and lectin pathways of complement MBL is a collectin, and is one of a number of serum proteins collectively known as opsonins MASPS (Mannose-binding lectin-Associated Serine Proteases) couple collectins to the complement pathway Before ligand binding, MASPs lack protease activity. Binding of multiple carbohydrate recognition domains of MBL to the microbial cell surface leads to conformational changes in the molecule, which promotes proteolytic activation of the MASPs, which the initiate the complement cascade
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Defence against Candida albicans?
In main deck Activation of complement + Interactions of cell wall components, such as mannoproteins and beta- glucan, with phagocyte receptors such as TLR2 and dectin-1 stimulate release of cytokines including IL-1, IL-6 and TNF. phagocytosis by neutrophils and macrophages. Phagocytosis triggers the production of appropriate innate fungal killing mechanisms Production of cytokines by activated neutrophils, together with direct interaction of neutrophils with dendritic cells* within inflammatory sites, promotes the maturation of dendritic cells, = adaptive immunity is activated.
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Innate cell killing of parasites?
Neutrophil mediating killing: Neutrophil extracellular traps… (Trojan horse) Macrophage: PRR activation and take up parasites (and infected neutrophils) via phagocytosis and enter phagosome Killing: Reactive oxygen species (ROS), triggered by phagocytosis Production of nitric oxide… Induced by IFNγ (Need help from Th1 CD4+ T cells!)
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Against parasites what type of T cell is better at killing them?
Against parasites what type of T cell is better at killing them? Th1 cell rather than a Th2 cell The Th1 produces IFN-y cytokines that activate M1 macrophages which produce iNOS which produces nitric oxide which kills the parasites Regulatory T cells can also suppress immunity and macrophage function The effector functions of the pathogen specific CD4+ T cells determines the outcome of disease
149
Overall summary on parasites?
Overall summary on parasites? Type 1 immunity for protoza Type 2 immunity for Metazoan Balanced immunity is essential to avoid host damage
150
Main types of vaccine?
Live vaccines Living, but cannot cause disease Killed vaccines Killed by heating, or exposure to chemicals Sub-unit vaccines Fragments of the microorganism e.g. proteins (or polysaccharides) Almost always antibody mediated In some cases an immune response against a single protein antigen elicits protection Nucleic acid vaccines (DNA or mRNA) Direct protein expression after injection Vectored vaccines DNA encoding the sub-unit is cloned into another “safe” microorganism
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What is formaldehyde detoxification?
What is formaldehyde detoxification? Removes toxicity of a protein The immunogenicity of the protein is preserved Problems: Must balance cross linking with retention of antigenic structure Batch to batch variation Reversion Requires pure toxin at the starting point: Needed to grow pathogen Need to purify and handle the toxin
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What are genetic toxoids?
Modern approach to subunit vaccines against toxins Modify the gene so that it encodes a non toxic (but immunogenic) protein
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Describe e toxin?
causes enterotoxaemia in livestock Produced in intestine crosses gut wall, targets kidneys and brain causing death Can mutate the toxin now 1000 fold less toxic Is a vaccine
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Diphtheria toxin CRM197 genetic toxoid?
In main deck Mutation in the catalytic A-subunit blocks activity Glycine to glutamic acid substitution at residue 52
155
Advantage of genetic toxoids?
Produce in harmless bacterium High yields Molecular structure more similar to active toxin Reproducible properties No reversion
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Sub unit vaccine against plague?
In main deck F1 antigen - capsule and V-antigen part of the type 111 system are the protective components Then produce F1 and V antigens using genetic engineering Together produces solid protection
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What's reverse vaccinology?
Predict vaccines from the genome sequence pSORT predicts cellular location so can help us find proteins that will be on the surface will give lots of proteins then you have to test them
158
Sub unit vaccines are effective at stimulating protective antibodies which will?
Agglutination Opsonization Neutralization Activation of complement Inflammation Antibody - dependent cell mediated cytotoxicity
159
s there immunological cross reactivity between the different polysaccharides on bacteria?
No they are unique
160
Diseases where CD+ T cells play a role in protection?
Diseases where the microbe grows within host cells tuberculosis • salmonellosis • melioidosis • viral infections yellow fever influenza Measles SARS CoV2
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How are CD8 + responses induced?
induced by live attenuated microbes that can invade host cells Usually very effective – excellent mimetics of the natural microbe Risk is that they will still cause disease in some individuals e.g. immunocompromised Activates Another approach: Injected DNA or mRNA is taken up by host cells The protective sub-unit is produced by host cells and seen as foreign by the immune system Protein antigen is processed via the MHC I (and MHC II) pathways. Combine the advantages of live and sub-unit vaccines Work well in animals not really humans
162
Vector vaccine?
nset gene encoding the protective subunit into a “harmless” microbe • A wide range of carrier microbes have been suggested e.g. – Disabled Salmonella – Lactococcus – Vaccinia virus
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Polyclonal vs monoclonal antibodies?
Because most antigens carry many different epitopes, animals injected with a single antigen will produce a complex mixture of antibodies, each made by a different clone of B cells This antibody response is said to be polyclonal and will not discriminate between different antigens To discriminate between different antigens, antibodies need to be identified that bind to epitopes specific to individual antigens These are known as monoclonal antibodies
164
Do cancer cells or malignant cells have unique epitopes?
yes
165
What is hybridoma technology?
Allows the identification and culture of cells secreting identical antibodies with pre-defined specificity A single clone of cells secreting a single antibody is made by fusing a B cell (Ig+ splenocyte with finite lifespan) with a myeloma cell (cancerous Ig- B cell with infinite lifespan) The resulting hydrid cells (HYBRIDOMAS) each make a specific monoclonal antibody
166
Time course of a typical immune response when injected with antigen?
In powerpoint Primary injection: Production of IgM Multivalent Low affinity Secondary injection: Production of IgG Bivalent Low to medium affinity Tertiary injection: Production of IgG Bivalent Medium to high affinity Multiple boosts: IgG Bivalent High affinity
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Mechanism of hybrid cell selection in HAT medium?
HGPRT = Hypoxanthine:guanine phosphoribosyl transferase = blocks RNA and DNA transcription only can go through salvage pathway Spleen cell = HGPRT+ but is not able to grow in long-term Myeloma cell =HGPRT-, therefore not able to use the salvage pathway for RNA synthesis because the normal pathways are blocked Hybridoma cell = has HGPRT from a spleen cell and immortality from a myeloma cell, therefore is able to grow in the HAT medium (providing there is an exogenous supply of Hypoxanthine and Thymidine)
168
What is the PTA-ELISA?
Plate-Trapped-Antigen-Enzyme-Linked | Immunosorbent Assay
169
What is phage display?
What is phage display? An issue with hybridoma technology is immuno- dominance Alternative technologies to generate mAbs include phage display A technique in which antibody fragments are expressed as a fusion with a coat protein of a bacteriophage Fused proteins are displayed on the surface of the virion, while the DNA encoding the fusion resides within the virion
170
Making antibody combinatorial libraries?
259
171
Describe the expression of scFv on the surface of phage?
260
172
Describe the expression of F(ab) fragments on filamentous phage?
Describe the expression of F(ab) fragments on filamentous phage? F(ab) fragments of antibodies can be expressed on the surface of phage as fusion proteins with pIII Multiple copies expressed along the length of the phage particle
173
Uses of monoclonal antibodies?
In main deck Diagnostic pathology (cytology and histology) In vitro diagnostic assays based on e.g. Enzyme-Linked Immunosorbent Assay (ELISA), Lateral-Flow Assay (LFA) for pathogens and biomarkers of disease (Lectures 15 & 16) Affinity purification and characterisation of antigens Limited use of mouse mAbs in vivo until relatively recently
174
The need to humanise monoclonal antibodies?
Immunogenicity - most mAbs used in vivo are of mouse origin and are therefore XENOGENEIC resulting in Human Anti-Mouse Antibody (HAMA) reactions 2. Origin - Mouse origin diminishes their ability to elicit effector mechanisms such as COMPLEMENT-MEDIATED LYSIS or ANTIBODY-DEPENDENT CELL-MEDIATED CYTOTOXICITY (ADCC)
175
How does humanisation occur?
Use of xenoantibodies in human patients had proved to be severely limiting owing to their being seen as foreign proteins by the patient’s immune system Strategies adopted to increase the human content of antibodies which have proven clinical applications include: Production of human hybridomas from human B lymphocytes Replacement of the constant regions of mouse mAbs with those of human antibodies yielding CHIMERIC antibodies Replacement of complementarity-determining regions (CDRs) of a human antibody with those of a mouse antibody via CDR GRAFTING to make a HUMANISED antibody Production of FULLY HUMAN mAbs in transgenic mice
176
Human immune system mice?
265
177
The 3 phases of cancer immune surveillance?
Elimination: By B cells, antibody, T cells, Treg cells, NK caells This is the innate and adaptive immune response active against tumour Can result in tumour cells death Equilibrium: Tumour is contained by the immune system but not completely destroyed Escape: Tumour antigen editing via genomic instability causes immune evasion Tumour microenvironment becomes immunosuppressive
178
What does immunotherapy do?
What does immunotherapy do? Specific: Trains the immune system to recognise and target only cancer cells Powerful: Attacks the cancer systemically through out the body Universal: A treatment approach that can be applied to nearly all cancers Memory: Capacity for memory means durability of protection
179
Types of immunotherapy?
Passive vaccination (Therapeutic Monoclonal Antibodies) Active vaccination e.g. HPV vaccine (Gardasil, Cervarix) and cervical cancer Immune system modulators e.g. IL-2 (activates CD8 T cells) Immune Checkpoint Modulation Immune Cell Therapy
180
How do therapeutic monoclonal antibodies target cancer?
Carry cytotoxic agents to tumour Induce Complement-Mediated Lysis or ADCC of tumour cells e.g. Rituximab Block activity of tumour-specific proteins e.g. Herceptin Steps: Naked MAb Immunoconjugates Multistep targeting
181
New monoclonal antibodies for cancer
272-281
182
What is adoptive immune cell therapy: Normal TILs?
Idea behind this approach is that the TILs have already shown the ability to target tumor cells, but there may not be enough of them within the tumour to eradicate it or overcome the immune suppressive signals that are being released there Introducing massive amounts of activated TILs can help to overcome these barriers and shrink or destroy tumors In some experimental cases these treatment responses have lasted for years TILs are collected from samples of the tumor TILs that show the greatest recognition of the patient’s tumor in lab are selected Cells are then activated with cytokines and infused into the patient’s bloodstream
183
What is antibody guided molecular imaging?
``` Radio-labeled antibodies used in nuclear medicine to locate cancer cells (or infections) by molecular imaging using: ``` Computed Tomography (CT) Magnetic Resonance Imaging (MRI) Positron Emission Tomography (PET) - PET/CT or PET/MRI More details on 287
184
What is Ouchterlony immunodiffusion?
OID is a qualitative technique for detecting antibody-antigen interactions in which antigens and antibodies are placed in a gel of agar and allowed to diffuse towards one another A positive reaction is indicated by the presence of PRECIPITIN lines due to a Antibody-antigen equivalence = immune complex formation Antigen excess or antibody results in no precipitin
185
Precipitin that forms when both antigen sources react with the antibody as they both have shared properties?
An arc
186
Precipitin Line that forms when each antigen doesn't share a common determinant of the antibody but both have a determinant of it?
A cross sword
187
Precipitin line that forms when antigens share one common determinants but one of them has both required for the antibody
Arc on the side which doesn't have an extra shared one Spur forms on side that does, so cross bridge shape there
188
What is Western blotting?
A technique in which specific antibodies are used to identify particular antigens in mixtures of proteins that have been resolved and transferred to a membrane 293
189
Features of an SDS page?
The speed of migration in an electrical field depends on the dimension form and charge of molecules For deaggregation and denaturation of the proteins SDS, B-mercaptoephanol or DTT (reducing agents) and heat is used SDS provides negative charge to the proteins Right to left = separated by charge by isoelectric focusing (IEF) Up to down = separated by size by SDS electrophoresis
190
What is direct immunofluorescence?
What is direct immunofluorescence? Treatment on cell with labelled antibody Unbound antibody washed away and UV light applied Fluorescence observed where antigen is located
191
What's indirect immunofluorescence?
What's indirect immunofluorescence? Treatment with unlabelled primary antibody Unbound antibody washed away Treatment with labelled secondary conjugate Unbound conjugate antibody washed away UV light applied Fluourescnce observed where antigen is located
192
What's immune-electron gold microscopy?
A qualitative technique in which antibodies tagged with gold particles are used to detect molecules of interest EM-gold allows localisation of antigen-antibody interactions at the nm scale (cf. IF at the m) A powerful method of visualising intracellular antigens and organelles
193
Rhizoctonia solania case study?
301 and 302
194
Aspergillus case study
304 to the end