Immunology 4 Flashcards
What determines whether glucocorticoids have an immunosuppressive or an anti-inflammatory effect?
Dose administered
Outline some side effects of glucocorticoid use
- Blanket immunosuppression so susceptible to secondary infections
- Mimic endogenous glucocorticoids and so chronic use may lead to iatrogenic hyperadrenocorticisim
- Abrupt withdrawal can lead to Addisonian crisis
Explain how immune mediated haemolytic anaemia (IMHA) may occur
- Lots of mechanisms
- Coagulation: cross-liinking of antibodies, leading to thrombus formation
- Recognition of Ab Fc region by Fc receptors on macrophages/neutrophils => phagocytosis of RBCs
- Recognition of Ab Fc region, activate complement, opsonisation and phagocytosis
- Alloantibpdy rendering RBC susceptible to removal
- Drugs/infection modifying antigen leading to destruction
Describe the treatment of immune mediate haemolytic anaemia with corticosteroids
- Reduce egress of inflammatory cells into tissues
- Reduction in inflammatory mediators
- Suppression of macrophage and neutrophil function
- Lymphocytotoxic
- Reduced macrophage Fc receptor expression
- Inhibition of complement
What is atopic dermatitis/atopy?
Type I hypersensitivity reaction to environmental allergens
Explain how atopic dermatitis occurs
- Occurs when percutaneously absorbed allergens bind to Langerhans cells
- Production of allergen specific IgE antibodies
- Bound to surface of circulating basophils and mast cells
- Degranulate when come into contact with allergens, release inflam mediators e.g. histamine, heparin
- Results in pruritus and erythema
Describe acute atopic dermatitis specifically
- Early stages of immune response
- IgE mediated mast cells phenomenon
- Th2 cytokines involved
- On re-exposure, IgE already produced, binds to allergen, many already bound to mast cells by FcR, release inflam mediators
Describe chronic atopic dermatitis specifically
- Recruitment of multiple cell types
- Immune mediators of Th1
- Leads to irritation
- Secondary infection may occur
Outline the treatment options for atopic dermatitis
- If no sensitivity testing, then prednisolone
- If sensitivity testing, then hypoimmunisation following identification of allergen
- Shampoo to alleviate worst symptoms
- Histamine
Describe the therapeutic treatment of atopic dermatitis
- Systemic/topical corticosteroids
- Cyclosporine (atopica), inhibits T lymphocyte function
- Oclocitaib maleate (apoquel): selective molecule which inhibits Janus kinase 1 (JAK1) signalling pathway (part of itch)
- Monoclonal anti-canine IL-31 antibody (itch cytokine, new method)
What are autologous biological products?
Products prepared from whole blood of individuals and adminstered back to the same individual
What is IL-1beta?
- Pleiotropic cytokine affecting many biological functions
- One of first cytokines produced in inflammation (leads to fever, inappetance)
- Produced by, and stimulates innate immune cells (incl maturation of APCs and production of inflammatory cytokines)
Outline the use of IL-1Ra
Usually horses, osteoarthritis treatment, administered intra-articularly
Explain how IL-1Ra works
- Competitive inhibitor of IL-1beta
- Steric hindrance
- Does not have intracellular signalling capability so no production of effector proteins
Where do NSAIDs exert their action?
On COX-1 and COX-2 in the arachidonic acid metabolism, preventing production of eicosanoids (PGs and thromboxane)
Where do corticosteroids exert their action in arachidonic acid metabolism?
On annexin A1 (phospholipase) (required to release arachidonic acid from phospholipid membrane)
Describe the arachidonic acid (Aa) metabolism
- Aa esterified in membrane phospholipid
- Phospholipase A2 isolates arachidonic acid
- Arachidonic acid produces prostagland G2
- Metabolised by COX1 or COX2 to produce prostaglandin H2
- Tissue specific isomerases produce either prostacyclin, thromboxane, prostaglandin E2 or prostaglandin F2alpha
What is the action of thromboxanes and prostaglandins?
Vasoactive lipids
What is produced if arachidonic acid is metabolised by lipoxygenase pathway?
- Production of leukotrienes
- lead to pain, fever, vascular permeability increase, chemotaxis of PMNs
What is the risk of blocking COX-1?
Can lead to ulceration and bleeding of gastric mucosa, therefore blocking COX2 is preferable
Give examples of natural food supplements that may have anti-inflammatory properties
- Devils claw
- Green lipped mussel
- Glucosamine
- Chondroitin
What is primary immune deficiency?
- Appears early in life
- Rare immune gene mutation
- Genetic/congenital and may be hereditary
What is secondary immune deficiency?
- Occurs in adult which has previously been normal
- Occurs due to secondary factors e.g. age, drugs, chronic disease or infection
Give examples of primary canine immunodeficiencies
- Canine IgA deficiency
- Canine leukocyte adhesion deficiency (CLAD)
- X-linked severe combined immunodeficiency (X-SCID)
Describe the occurence, cause and biological effect of canine IgA deficiency
- Common, Shar Pei, GSD
- Not mutation in gene, functional deficiency in IgA production
- Sub-normal IgA, mild chronic mucosal infections
Describe the occurrence, cause and biological effect of canine leukocyte adhesion deficiency
- Rare, red Irish Setter
- B2 leukocyte integrin CD8 gene mutation
- Blood neutrophils cannot adhere to vascular endothelium enter tissues
- Neutrophilia
- Multiple systemic infections
Describe the occurence, cause and biological effect of X-linked severe combined immunodeficiency (X-SCID)
- Rare, Bassett hound, Cardigan Welsh corgi, Jack Russell terrier, Arabian horse
- Bassett X linked, not X linked in Corgi
- IN JRT mutation in DNA protein kinase gene
- Cytokine receptors mutated, T cell response to antigen inhibited, no immune response
- Viral andbacterial infections post colostral Ab decline
- Lymphopaenia, hypoplastic lymphoid tissue
- IgG and IgA absent
Explain how CLAD leads to loss of expression of beta-2 integrins
- Lack of CD18 expression
- Is a beta-2 subunit, and required to make up this surface receptor
- Cannot bind to CD-11 so beta-2 integrin cannot be formed or function
What are the 6 causes of secondary immunodeficiency?
- Immunosensecence
- Drugs
- Malnutrition
- Stress
- Concurrent disease
- Chronic disease
Describe the effect of FIV on the immune system
- Can cause secondary immunodeficiency
- Enlargement of lymph nodes, are also site of viral proliferation
- Decrease in CD4+ T cells, inverted CD4:CD8 ratio occurs
- Lymphocyte blastogenesis to T and B cells mitogens is impaired
- decrease in production of Th1 cytokines (due to reduced CD4+)
- FIV replicates in lymphocytes
Describe the acute phase of infection with FIV
Mild illness, progressive decline in blood CD4+ T cells
Describe the second phase of FIV infection
- Asymptomatic
- Continued CD4+ T cel decline over many years
- CD4:CD8 ratio declines
Describe clinical disease caused by FIV
- Recurrence of mild illness, progresses to severe terminal stage 4-5 of disease
- Chronic, multi-systemic diseases including gingiovitis, respriatory tract infection, enteritis, dermatitis, weight-loss, pyrexia, lymphadenopathy
- Neurological disease and lymphoma may develop
- Secondary infections may occur
How is FIV detected?
PCR of viral nucleic acid in lymphocytes, or FIV specific serum Ab
What disease is often concurrent with FIV?
FeLV - also immunosuppressive
List the uses of ELISAa
- Disease detection
- Detection of illegal drugs in sport animals
- Detection of hormone
What is measured by an indirect ELISA?
Antibody concentrations in whole blood, plasma or serum
- May be antibodies leading to immune complex formation (rheumatoid factor), antibodies to pathogens, autoantibodies
Describe the process of an indirect ELISA
- Antigen bound to plastic well
- Test sample added, any antibodies that react against antigen will bind
- Wash
- 2ndary antibody conjugated to enzyme added, binds to antibodies from sample
- Wash
- Add substrate, converted by enzyme bound to antibody
- View/quantify result using a spectrophotometer
What is measured in a Sandwich ELISA?
Antigen concentrations in various samples
Describe the process of a Sandwich ELISA
- Wells coated with capture antibody
- Test sample added, antigens bind to capture antibody
- Wash
- Add primary (detection) antibody
- Wash
- Add 2ndary antibody conjugated to substrate specific enzyme
- Wash
- Add substrate, converted by enzyme, view/quantify result using spectrophotometer
What is C-reactive protein (CRP) a marker of?
Inflammation, may also be a marker of disease outcome
What is a competitive ELISA used for?
Detection of small antigens with only 1 epitope )e.g. prostaglandin, cortisol) and so sandwich ELISA would not be possible
Describe the process of a competitive ELISA
- Wells coated with capture antibody
- Enzyme-labelled competing antigen and samples added to wells and compete for binding to the capture antibodies
- Wash
- Substrate added, converted by enzyme if present
- Amount of bound labelled antigen inversely related to the concentration of antigen in the test sample
What is test sensitivity?
The ability of a test to identify positive results i.e. the proportion of positive animals that will give a positive test result, can be used to rule out disease (if is negative, unlikely to be false)
What is test specificity?
The test’s ability to identify negative results, i.e. the proportion of animals that are known to be healthy who will test negative for the disease, can be used to rule in disease (if a test is positive, is unlikely to be false)
What is the use of assessing seroconversion in paired samples?
Increase in antibodies on second sample, where was previously low, shows seroconversion and therefore suggests infection
What is the function of the Coomb’s test?
To identify presence of non-agglutinating antibodies on the surface of particles such as bacteria or erythrocytes
- e.g. assessing neonatal isoerythrolysis in horse and mule foals, immune mediated haemolytic anaemia in dogs and cats
Describe the process of the Coombs test
- RBCs covered in antibodies naturally
- Antiglobulin added, agglutination occurs if specific antibody is present
What is radial immunodiffusion used for?
Demonstration of precipitation of antigen by an antibody
Describe the process of Radial immunodiffusion
- Antigen solution diffuses into agar with specific antiserum
- Ring of precipitation forms around antigen well
- Area of ring is proportional to the amount of antigen in the well, plotted on standard curve
What are direct and indirect fluorescent antibody tests used for?
- Direct: identify presence of antigen in a cell or tissue sample (direct binding)
- Indirect: identify presence of either antigen in a cell or tissue sample, or antibody in serum
Describe the process of immunofluorescence immunodiagnostic tests
- Use fluorescent dyes e.g. FITC (fluorescin isothiocyanate)
- Chemically linked to antibodies without affecting their reactivity
- Require stimulation by specific wave length
- Fluorescence visible under microscope when binds to antigen and is not washed off
What is the anti-nuclear antibody test used for?
Diagnosis of systemic lupus erythematosus, due to development of autoantibodies against antigens located within cell nucleus
Describe the process of the anti-nuclear antibody test
- Demonstrated by indirect immunofluorescence
- Cultured cells or frozen section on microscope slide used as source of antigen
- Dilutions of patient’s serum applied
- Incubation with fluorescin labelled antibodies specific to patient species antibodies
- Microscopic analysis
- If patient produces nuclear antibodies, then nuclei will be fluorescent and indicates positive result
What are the principles of herd health production management?
- Monitoring and appraising, continual active process
- Regular vet visits
- Overview of preventative systems
- Optimise herd health and welfare as well as farm sustainability and profitability
Describe the colour coded classification system for Johne’s disease
- Management of repeated testing regimes
- Red: to cull before next calving, have repeated positive ELISA
- Yellow: reactive within past year, but not repeated positive results, may shed MAP
- Green: not reactive at time of testing
What actions should be taken with yellow classified Johne’s cows?
- Calve in individual pens
- Remove calves within 15 mins of birth
- Calves should not be exposed to the manure of any cows
What samples can be used for detecting BVDV?
- Individual milk samples
- Bulk milk samples
- Serum samples
Give examples of potential pathology when antinuclear antibodies combine with free antigen to form immune complexes
- Deposition in glomeruli = membranous glomerulonephritis
- Deposition in arteriolar wall = fibrinoid necrosis and fibrosis
- Deposition in synovia = arthritis
- Formation of haematoxilin bodies in skin, kidney, lung, spleen and heart
- Formation of “lupus erythematosus” cells in bone marrow
In what conditions are anti-nuclear antibodies formed?
- Systemic lupus erythematosus
- Immune mediated non-regerenative anaemia
- Ehrlichiosis
- Bartonellosis
- Some normal dogs
- Other infectious and non-immune mediated inflammatory diseases
Define immunopathology
Pathology caused by the immune response
Name the 4 major categories of immune mediated disease
- Hypersensitivity
- Immune neoplasia
- Autoimmunity
- Immunodeficiency
Give the predisposing factors for immune mediated disease
- Gender
- Genetic predisposition
- Hormonal changes
- Microbes
- Drugs/vaccines and the environment
Outline how immunopathology links to immune homeostasis
- Immune system tightly regulated
- Normally when challenged, appropriate responses are initiated aimed at restoring homeostasis
- Where return to normal baseline does not occur, immune mediated pathology can develop
Give examples of type IV hypersensitivity
- Environmental allergy e.g. pemphigus foliaxeus
- Granulomas formed after infection with Mycobacterium spp
Outline the mechanism underlying type IV hypersensitivity
Delayed reaction mediated by T cells (Th1) that activate macrophages
Explain how a granuloma develops
- Cellular attempt to contain offending agent
- Epithelioid macrophages surrounded by mononuclear leukocytes
- Wall off agent
What is the role of IL-10 in immune homeostasis?
- Anti-inflammatory cytokine
- Dampens CMI by inhibiting Th1 cells, NK cells and macrophages
What is the role of IL-1Receptor antagonists in immune homeostasis?
- A protein that prevents the pro-inflammatory cytokine IL-1 from binding to its receptors
- Therefore reduces inflammation
What is a disadvantage of TNFalpha release?
- Released with other cytokines as part of cytokine storm in response to bacterial endotoxins
- Can lead to septic shock
What is a disadvantage of neutrophils?
- Immune mediated polyarthritis with fever and painful, swollen joints
- Neutrophils invade multiple joints
What is a disadvatage of CD8+ T cells?
Involved in autoimmune disease
By what timepoint will passive immunity wane in puppies?
8-12 weeks
What are the recommendations for vaccinationof puppies?
- DHP
- Initially at 6-8 weeks of age, then every 2-4 weeks until 16 weeks of age or older
- Booster vaccine at 12 months old or 12 months after last primary series of puppy vaccines
What is the core recommendation for cat vaccination?
- FPV, FHV-1 and FCV vaccine
- Begin at 6-8 weeks old, repeat every 2-4 weeks until 16 weeks of age or older
- Booster at 12 months old or 12 monhs after last of primary series of kitten vaccines
What is meant by pet socialisation?
Preparing a pet to enjoy interactions adn be comfortable with other animas, people, places and activities
When should pet socialisation be started?
During the sensitive period, which is between 3 and 14 weeks for puppies, and 3 and 9 weeks for kittens
What can be done in the prenatal period to aid emotional development of pups?
- Emotional state of dam most important in this time
- Fussing the relaxed bitch results in offspring more able to resist physical stress and less susceptible to emotional disturbances
What behaviour developments occur in the puppy’s neonatal period?
- Birth to 2 weeks
- Puppy motivated by contact, comfort and suckling
- Capable of learning olfactory and tactile associations
- Short periods of handling produce dogs that are more resistant to stress
Describe the behavioural developments that occur in the puppy’s transitionary period
- Between days 13 and 21
- Focus of development moves to social awareness and identity
- Playfighting begins and puppies can display distress vocalisation when separated
Describe the behavioural developments that occur in the puppy’s socialisation period
- Between 3 and 12/14 weeks
- Environmental effects have huge influence on development of behaviour
- Puppies begin to interact with social and environmental stimuli
Describe the behavioural developments that occur in the puppy’s juvenile period
- 12-14 weeks to 6 months (sexual maturity)
- Timings of development vary with breed
- development of motor capacities limited to improvements in strength and skill
Describe the behavioural developments that occur in the dog’s adolescent period
- Begins at sexual maturity, ends at social maturity (18-24 months)
- Substantial breed variation (larger take longer to mature physically ad socially)
- Characterised by refinement of social skills
Describe the behaviour developments that occur in the dog’s adult period
- Begins when dog reaches sexual maturity
- Most stable stage of behaviour development
- Followed by old age where there is a progressive decline in physical and psychological functioning
