Immunology Flashcards
Why is immunology important to vet med
Recovery from infection
Vaccination to prevent infection
Allergy and autoimmunity
Inflammation
What happens when we are infected with a microorganism
Detect the microorganism
Capture/ phagocytose the microorganism
Destroy the microorganism
Innate immunity has what factors
Physical barriers
Secretions
Enzymes
Complement
Phagocytose cells
Nk cells
Interferons
Intrinsic immunity has what factors
Restriction factors- TRIM5, APOBECs, Tetherin, SAMHD1
Adaptive immunity has what factors
Antibody
Helper T cells
Cytotoxic T cells
What does adaptive immunity develop
Develops in response to antigens on the invading organism
What are the two key attributes to the immune response
- Specificity
- Memory
What can macrophages detect
Lipids
Sugars
Other molecules unique to invading organisms
What can invading organisms be destroyed by
Engulfing by phagocytosis
What can be trapped in nets
Neutrophils
Phagocytosis cells kill microbes by
Oxygen dependent mechanisms
Oxygen independent mechanisms
What is oxygen dependent killing
Oxygen is needed to kill pathogens
Protective mechanism in macrophage through hydrogen peroxide to water using catalase
What is oxygen independent killing
Low molecular weight defending
Cathepsin G
Cationic proteins
Bacterial permeability increasing protein
Lysozyme function
Destruction of bacterial cell wall
Lactoferrin function
Chelation of iron
Proteolytic enzymes and hydrologic enzymes function
Digestion of ingested organisms
Microbicidal activity involves
Oxygen dependent killing
Oxygen independent killing
Inflammation and fever involves
IL-6, TNFa, IL1
Prostaglandins
Complement
Clotting factors
Lymphocyte activation involves
Antigen processing
Antigen presentation
IL1 production
Tissue reorganisation involves
Elastase, collagenase, hyaluronidisc
Fibroblast stimulating factors
Angiogenesis factors
Modulation of the immune response involves
IL12
Th1
Il10
TH2
What does complement do
Targets the immune response to the invading organism
What does triggering complement contributes to
The rejection of xenotransplantation organs
What is the pathway of complement activation pathway
Microbe enters the body
Complement C3b binds to microbial surface and is stabilised
C3bBb complex forms and splits more C3 into C3a and C3b
Cleavage products C3a and C5a promote local inflammation
C3a and C5a attract leukocytes to the site of infection
C3b coated microbe is phagocytosed
Assembly of the membrane attack complex on the microbial surface triggers lysis
Structure of an antibody
Fc receptor binding site
Complement fixation
Antigen binding at either end
When do the hormones peak at Primary response to antigen
IgM peaks at 7 days
IgG peaks at 14 days
Hormones involved in response to an antigen
IgM
IgG
Secondary response involves
A sharp increase of IgG
Steady increase of IgM
What happens with hormones in antigen response
IgM is released first followed by IgG
Secondary response features
Takes less time to respond
Larger response to the recovery threshold
Allotypic variation is
Variation in the amino acid sequence between light and heavy chains
Isotypic variation is
The heavy chain a certain way or light chain a certain way
Idiotypic variation is
Variation in the antigen binding domain
Immunoglobulin structure
Light chain and heavy chain is where an antigen binds
Then there is a hinge region which is flexible and can rotate
They are symmetrical
CL shows allotypic variation
Variable domain at VDJ
What is hinge region
Flexible and can rotate
Passive transfer is through what
The colostrum and properties are species specific
What is an epitope
Binding site on antibody that antigen binds to
Epitopes can either be
Linear
Conformational
In humans what amount of polymeric IgA is translocated to the gut daily
40mg per kg
What is estimated daily production of IgG
30mg per kg
IgG in response to antigen
Secondary response
IgG with receptor binding what
Fc
What does IgG do
Neutralises antigen
Fixes complement
Is IgG high affinity
Yes due to affinity maturation
What structure is IgM
Pentameric
What response is IgM
Primary response
Is IgM a low affinity
Yes
What does IgM do
Neutralises antigen
Fixes complement
How many binding sites does IgM have
10
In IgA what is special about the hinge region
Heavy glycosylation
In IgA what component is present which isn’t in other immunoglobulins
J chain
What type of structure is IgA
Dimeric or tetrameric
Features of IgA
Secreted immunoglobulin, resistant to proteolytic degradation
Secretory component mediates transport across epithelial surfaces
IgD is expressed on the surface on what type of cell
B cell during developmental phase
What is IgD use
Facilitator of immunity to respiratory bacteria
What are antibodies produced by
B cells
Where are B cells produced
Bone marrow
Foetal liver
Bursa of fibricus- birds
IgE triggers the release of what
Histamine
What does histamine release
Mast cell degranulation
Is IgE is expressed on what cells
Mast cells
Basophils
Monocytes
B cells derive from where
Hematopoietic stem cells
What are virgin B cells
Newly formed B cells
Features of virgin B cells
Short lived
75 percent leaves the BM
What antibodies are present on B cells
IgM
IgD
Where do gene rearrangements occur in BM
Variable region rearrange to generate VDJ and VJ
Where do gene rearrangments occur in lymphoid tissue
Isotype- class switching- occurs following stimulation of virgin B cell with antigen
What are the lymphoid organs
Lymph node
Spleen
Bone marrow
Thymus
GALT
Vaccination mimics what
Re exposure to a pathogen
Where do B cells encounter antigens
B cells and T cells traffic to lymphoid organs
Where are B cells made
Bone marrow
Where are T cells made
Thymus
How are antigens carried to lymphoid tissues
Lymphatic systems
B cell trafficking pathway
Bone marrow then B cells leave BM and enter blood vessel to the medulla
What parts are involved in the lymph node
Afferent lymphatic
High endothelial venue
Germinal centres
Efferent lymphatic
Medullary chords
B cell area
T cell area
What causes travel of lymphatic fluid
Simple act of motion
What direction is the movement of lymphatic fluid
Unidirectional
What does vaccine need to come into contact with in draining lymph fluid
B and T cells
Where can u vaccinate in the body
Everywhere
Lymphatic circulation pathway
Interstitial fluid
Lymph capillaries
Collecting lymph vessels
Lymph node
Lymph duct
Lymph trunks
Venous system
What vessels have a beaded appearance
All vessels except lymph capillaries
What do semilunar valves do
Ensure flow in one direction
Germinal centre consists of what
Helper T cell- producing cytokines
Dendritic cells
Some of these cells will make memory cells
Pathways of germinal centres
B cell to encounter with antigen to secondary lymphoid follicle to germinal centres
Pathway of centroblast
Centroblast
Centrocyte
Lymphoblasts
Memory B cells or plasma cells
What are B cells competing for
Antigen
What happens when antigen levels decrease
Affinity increases
If affinity increases what happens
More likely to survive the cells
Times of vaccination selects for what
Best affinity
How is the thymus formed
Gene is switched on and then cells congregate and the thymus forms
What happens to your thymus as you get older
Decreases in size and you become more immune deficient
Cells within the thymus are called
Thymocytes
What do the cells go into the thymus as and leave as
Go in as precursors and leave as T cells
Thymus structure and components
Cortex- cortical epithelial cell, trabeculae, thymocyte
Medulla- macrophage, medullary epithelial cell, hassals corpuscle, dendritic cell
What mutation do nude mice have
FOX1 gene
Do nude mice have a functioning thymus
No- virtually no T cells
The impact on nude mice FOX1 gene the impact on this acquired immune response is
Defective antibody formation
No cell mediated response
No delayed type hypersensitivity
No killing of malignant or virus infected cells
No graft rejection
Thymic selection pathway
Nurse cell
Blast cell
Thymocytes
Gene rearrangement
To CD4/CD8
TCR expression
Interdigitating cell
Macrophage
Naive T cells
What is positive selection
Interaction with MHC class 1 or MHC class 2 on cortical epithelium
Do T cells kill parasites
Yes
what does CD4 do
Stabilise interactions with receptors
Helper T cell uses what CD
CD4
Cytotoxic T cell uses what CD
CD8
Dendritic cells instruct what
Helper T cells to respond in an appropriate way
T cells promote what
Cellular response
Once activated what can T helper cells do
Interact with B cells and support their expansion
Humoral immunity
B cell proliferation
Class switching
Increase Ig production
Th17 promotes
Neutrophil response
What do TH2 cells favour
Humoral response
Induce mast cell production
What happens when neutrophils kill a cell
Neutrophil
Cytotoxic T cells do what
Kill cells as they tigger cell death
What are granules
Modified lysosomes that contain effector proteins in an active form
What do NK cells recognise
Stress signals
natural killer cells have a high number of what on their surface
Fe receptors
Pattern recognition receptors
Pathogen associated molecular patterns- PAMPS
Damage associated molecular patterns- DAMPS
What does PAMPS and DAMPS do
If something is dangerous and recognising a foreign body
What is antigen presentation
Display of processed peptide fragments to T cells for recognition by their T cell receptor
What mechanisms have macrophages developed with which they can sense danger
Mannosyl fucosyl receptor
CD14
Fc receptors
Complement receptors
MHC class 2
What is the function of mannosyl fucosyl receptors
Bind to sugars on the surface of microorganism
CD14 function
Bind to lipopolysaccarhide receptor
Fc receptor function
Bind to immunoglobulin and triggers phagocytosis
Complement receptors function
Bind to complement factor on surface of microbe
MHC class 2 function
Antigen presentation to T cells
In histology the red is
Dendritic cells
What is MCH class 1 responsible for
Peptide binding groove- non covalent
What is MCH class 2 responsible for
Alpha and beta chains
What are peptides recognised by
Human MCH class 1
Anchor residue function
Holds the peptide
Cheetahs affect with the MCH system
Cheetahs are inbred and have less genetic MCH diversity this causes a lessened immune response
A killed vaccine doesn’t have what type of cell
Cytotoxic T cells
What does live attenuated vaccine route of antigen processing
Make cytotoxic T cell
Why do we need the MCH system
If we all had the same MHC molecules then we would have a limited ability to protect ourself against antigens
Allow infinite diversity against different pathogens
Diversity of MCH molecules means more immunity
Small tight population means that there is not enough MCH
What happens when we loose MCH expression
CTCV cells down regulate MCH and secrete immunosuppressive cytokines
Deregulates MCH so we cant see it on the surface and means tumour cells can grow and develop
What did vaccination start with
Smallpox vaccine
Killed vaccines
No longer able to replicate following treatment
Protection is short lived
Booster needed
Killed vaccine examples
Rabies
Lepto
Live attenuated vaccines
Usually more potent than killed vaccines as limited viral replication
Antigen is produced by exogenous and endogenous pathways- stimulate cytotoxic T cells
More potent so selects for high affinity B cells so higher affinity maturation which causes a longer immune response
Live attenuated vaccine examples
Kennel cough
Subunit vaccines
Protective virus neutralising antibodies tend to be directed against surface proteins of the virus
Examples of subunit vaccine
Canine herpes virus
Strangles
Vectored vaccine function
Using attenuated virus to deliver gene encoding
Examples of vectored vaccine
Feline leukaemia virus
Advantages of inactivated vaccine
Safety- no reversion to virulence
Do not induce disease
Induce response against multiple viral proteins
Inexpensive
Antigen consistence
Stable at room temperature
Disadvantages of inactivated vaccine
Need to ensure complete inactivation
Response may require adjuvant
Cellular components may cause side effect
Cold chain required for storage and transport
More than one injection is usually required as antigen does not persist
Live attenuated advantages
Antigenic epitopes are preserved
Antigen persists, response may be long lived
Inexpensive
Administration across mucosal surfaces
Live attenuated vaccine disadvantages
May revert to virulent form
May induce disease in weakened immune system
Cellular components may cause side effects
Sub unit advantages
Safe
Focussed immune response
No hazards associated with production
No cellular contaminants
Sub units disadvantages
More than one injection may be required as antigen does not persist
Cold chain required for storage and transport
Response may require adjuvant
Advantages of vectored vaccines
Single gene
Mostly safe
Focused immune response
No hazards associated with production
No cellular components
Oronasal delivery possible
Endogenous and exogenous antigen presentation
Disadvantages of vectored vaccines
May not induce response to tertiary structures
May cause mild pox virus symptoms
Response to vaccine may be weak
Response to vector may affect subsequent doses
What is the perfect vaccine
A good safety profile
Highly efficacious
Induce both Humoral and cellular immunity
Minimal requirement for boosting
Goofed breadth of immunity against diverse viral stains
Stability and ease of administration
What is an adjuvant function
Enhance immune response
How does an adjuvant work
Danger hypothesis takes something non dangerous and switch on antigen presentation by promoting uptake of antigen presenting cells or by switching on macrophages
Autoimmune reaction represents what
A breakdown of self tolerance
What is tolerance
State of unresponsiveness that is specific for a particular antigen and which is induced by prior exposure to that antigen
Dizygotic twin calves in tolerance. What happens
They can exchange haemotopoietic stem cells as a result of placental fusion.
The twins are thus tolerated to each others MHC molecules
In peripheral tolerance, the endothelial barrier segregates what
T cells from self antigens
In peripheral tolerance, what triggers an immune response
Self antigens that present in insufficient quantities
What is clonal deletion
When high levels of self antigen is present which causes destruction of B cells
Autoimmunity arises through bypass of the control of
Autoreactivity
Autoimmune conditions
Addisons disease- adrenal glands
Rheumatoid arthritis
Myasthenia gravies
Immune mediated haemolytic anaemia
SLE
What is the full name of an ELISA
Enzyme linked immunosorbent assay
Method of ELISA
Add test sample to well of ELISA plate
Wash well to remove unbound antigens
Add antibody enzyme conjugate
Wash well to remove unbound conjugate
Add chromogenic substrate for enzyme
Read absorbance on microplate reader
What does monoclonal antibody grab onto in ELISA plate
Antigen
Pathway of ELISA
Monoclonal antibody grabs onto antigen and anchors it on the ELISA plate.
Then remove unbound antigen then add second antibody.
This will recognise a different epitopes in order to detect that second antibody, the antibody is coupled with an enzyme
What is the amount of antigen in an ELISA well directly proportional to
Amount of conjugated enzyme
Amount of antigen is directly proportional to
The amount of colour change
In immunoassay Less colour has
More progesterone
Immunoassay using labelled competitor method
Add test sample- 10ml to well of elisa plate
Progesterone in the sample bins to coating antibody
Add progesterone enzyme conjugate 200ml
Wash well to remove unbound progesterone enzyme complex
Add chromogenic substrate for enzyme
Immunoblotting also stands for
Western blotting
In electrophoresis proteins are separated firstly by
Size
Western blotting methods
Incubate blot with primary antibody
Wash
Incubate blot with enzyme conjugated secondary antibody
Wash
Incubate blot with substrate
Western blotting is washed.WHY
So there is no antibody’s left on the slide
No contamination occurs
Chromatin will go what colour
Completely blue
Enzyme catalyses colour change of what
No colour to colour
Immunodiffusion precipitates test size of ring is what to amount of antigen present
Directly proportional
Coombs test can be used for what
Haemolytic anaemia
Allergy is what
An overreaction of the immune system to a harmless antigen
What type of immune response does an allergy trigger
Inappropriate immune response
Hypersensitivity can be classed into four different sections
Class 1
Class 2
Class 3
Class 4
Class 1 hypersensivity
Binding of antigen to surface IgE
What hypersensitivity class is primarily on mast cells
Class 1
In class 1 what happens
Mast cell degranulation then an inflammatory response occurs
Class 2 hypersensitivity
Small molecules binding to cell surface components modify the antigency and render it immunogenic
In class 2 hypersensitivity b cells response to antigen does what to the cell
Destroys the cell
class 3 hypersensitivity
Soluble protein antigens bind to immunoglobulin forming immune complexes. Complexes are deposited in blood vessel walls and phagocytic cells pick them up and destroy them
Where are complexes in class 3 deposited
In blood vessel walls and phagocytic cells pick them up and destroy them
Class 4 hypersensitivity
Antigen specific T cells
Reactions to class 3
Arthrus reaction eg. Tetanus vaccine
Serum sickness eg. Drugs
Farmers lung
Hypersensitive penumonitis
Hypersensitivity type 1 features
Antigen- soluble antigen
Effector mechanism- mast call degradation
Reaction- asthma, allergic rhinitis
Granule contents- histamine, hepatin, proteases, enzymes, cytokines
What wont work with with an antihistamine present
Steroids
Antihistamines block binding of
Histamine so vasodilation doesn’t occur
What is harder to treat a chronic allergy or a acute allergy
Chronic allergy
Diseases hypersensivity class 1 symptoms
Asthma
Flares on skin
Coughing
Diarrhea
Atopic dermatitis- house mites and fleas
Food allergies
In horses- sweet itch- insect bites
Heaves- allergy to mould
Sweet itch symptoms
Alopecia
Atopical dermatitis
Thickening and ridgening of skin
Due to saliva of insect bites- manifests on horses coat
Hypersensitivity class 2 function
Can create an epitope
Only binds to rbc when drugs are present
Hypersensivity class 2 features
Antigen and altered cell surface components
Effector mechanisms- IgE binds to novel antigen, complement cascade triggered.
FcR targeting leukocytes. IgE binds to cell surface receptor- autoimmunity
Reaction- haemolytic anaemia
Drug modification of a protein antigen
Transfusion reaction- neonatal isoerythrolysis
Immunodeficiencies
Results of a defect in an immune response
Hypersensitivity class 3
Antigen- soluble antigen
Effector mechanisms- immune complexes, complement, phagocytes
How can neonatal isoerythrolysis be detected
Erythrocyte agglutination test
Hypersensitivity class 4
Soluble antigen
Effector mechanisms- macrophages, eosinophils
Reaction- asthma, contact dermatitis
When cells from immune system move into site of allergen exposure.
Delayed hypersensitivity of 1-3 days
IgA inherited deficiency
Secreted immunoglobulin
Resistant to proteolytic degradation
Secretory component mediates transport across epithelial surfaces
High affinity receptor on monocytes and neutrophils
Immunodeficiency is in response to
Viral infection
Viruses and infections to do with immunodeficiency
Lentiviruses
FeLV- thymic atrophy
Distemper
Parvovirus infection
Parasite infection- generalised immunosuppression
Atopic dermatitis is in what class of hypersensitivity
Type 1