Chapter 8 - Immune system and allergy Flashcards
What is the name for the group of cytokines that have a sole or major purpose to direct of the movement of cells involved in inflammation and the immune response?
Chemokines
Which cells express CD4?
MHC class II restricted T-helper cells
Which cells express CD8?
MHC class I restricted T-suppressor/cytotoxic cells
Which cells express CD3?
Mature T cells
Which cells express CD21?
Mature B cells
Which cells express CD79a?
All stages of B cell development and persists into the plasma cell stage
Which cells express CD90 (Thy-1)?
Dermal dendritic cells
Which immunologically important cytokine is stored by keratinocytes and released following cell damage?
IL-1
What is a unique feature of CD1 antigen presentation e.g. on Langerhans and dermal dendritic cells?
The ability to present non-peptide antigens to T-lymphocytes
Which cell adhesion molecule do Langerhans cells express that dermal dendritic cells do not?
E-cadherin - important for selective adhesion to keratinocytes
Which cytokines are particularly important for B-lymphocytes to differentiate into IgE-producing plasma cells?
IL-4 and IL-13
Match the below Th cells with the cytokines they produce:
Th1 cells
Th2 cells
IL-2, IFN-gamma, TNF-alpha
IL-4, IL-5, IL-10
Th1 cells produce IL-2, IFN-gamma, TNF-alpha
Th2 cells produce IL-4, IL-5, IL-10
Which histamine receptors mediate the anti-inflammatory action of histamine (inhibition of the release of inflammatory mediator substances from mast cells and other WBCs)?
H2 receptors
H1 receptors mediate the proinflammatory response
Which chemokines are considered most potent and selective for eosinophil chemotaxis?
Eotaxin
RANTES
Monocyte chemoattractant protein (MCP) 3 and 4
Arachidonic acid is metabolised into eicosanoids by which enzymes?
cyclooxygenases (COX)
Lipoxygenase (LOX)
Urticaria and angioedema result from degranulation of mast cells and which other cell?
Basophils (mast cell = major effector cell)
How can you differentiate gyrate urticaria from erythema multiforme?
EM does not pit on digital pressure and urticaria does
Name two breeds of horse that are at risk of developing atopic dermatitis?
Thoroughbreds
Arabians
What environmental factor predisposes horses to allergic contact reactions and why?
Moisture (e.g. sweating)
It decreases the effectiveness of the skin barrier and increases contact between the agent and the skin surface
Which type of Ig binds antigens and aids removal of them from intestinal mucus?
IgA
At what age do horses typically develop IBH?
3-4 years
Which pigmentary changes can be seen with IBH?
Melonoderma and melanotrichia
When present, which pattern of urticaria is seen with IBH?
Papular urticaria
Are mosquito nets effective in reducing Culicoides exposure?
No, they can still pass through the mesh - need ultrafine mesh screens/netting (60 squares per square inch)
Is IL-31 mRNA expression increased in lesional skin in Culicoides hypersensitivity?
Yes
In IBH, there is an IgE-mediated, type I hypersensitivity reaction to Culicoides allergens with activation of mast cells, followed by a late-phase reaction characterised by infiltration of which cells?
Lymphocytes and eosinophils
Is eosinophilia associated with severity in IBH?
Yes
In response to ASIT, IgG antibodies are produced, in particular ____ that block the binding of allergen-specific IgE antibodies to the allergens.
IgG4
ASIT is associated with decreased production of ___ and ___, the signature cytokines of Th2 CD4+ T cells, and an increase of the allergen-specific Treg with the production of regulatory cytokines, ____ and _____.
IL-4 and IL-5
IL-10 and TGF-β
Allergens from which Culicoides species have been identified and produced?
C. nubeculosus
C. sonorensis
C. obsoletus
Prophylactic use of intralymphatic injections in Icelandic horses with small amounts of recombinant allergens in Alum and monophosphoryl lipid A (MPLA, aTLR-4 agonist) resulted in what response?
Th1/Treg immune response (IFN-γand IL-10) with induction of high specific IgG (IgG1 and IgG4/7) antibodies levels, displaying a strong blocking capacity
In horses with IBH, linkage of equine IL-5 to virus-like particles of the cucumber mosaic virus (CuMV) generated polyclonal antibody responses against IL-5. What is the role of the virus-like particles?
- Small size (20–200 nm) enables free draining into the lymphatic systems and binding to B cell receptors
- Their surface is highly repetitive allowing B cell receptor cross-linking inducing potent antibody responses in absence of T cells
- Complement fixation via complement receptor 2 and subsequent follicular dendritic cell activation driving T cell–dependent differentiation of germinal center B cells into class-switched affinity-matured long-lived plasma cells
- Contain non-coding E.coli RNA activating innate immune receptors for pathogen-associated molecular patterns (PAMPs) such as toll-like receptor (TLR)-7
In horses with IBH, are the vaccine-induced anti-IL-5 antibody titres reversible?
Yes - important safety mechanism
A vaccine targeting which other cytokine has been studied for use in horses with IBH?
IL-31
In the study by Huhmann and Mueller (2019), topical application of PUFAs (1% concentrated fish oil [EPA, DHA], humectants and emollients – KERECIS Smooth) was used on half the body of horses with Culicoides sensitivity. What effect did it have on pruritus?
No significant effect
In the study by Huhmann and Mueller (2019), topical application of PUFAs (1% concentrated fish oil [EPA, DHA], humectants and emollients – KERECIS Smooth) was used on half the body of horses with Culicoides sensitivity. What effect did it have on lesion scores?
Significant improvement over 28 days
In the study by Huhmann and Mueller (2019), topical application of PUFAs (1% concentrated fish oil [EPA, DHA], humectants and emollients – KERECIS Smooth) was used on half the body of horses with Culicoides sensitivity. What adverse effects were seen?
Sun-burn like signs (erythema, scaling, swelling, crusts, alopecia) at sites of application (3/21)
Have ultrastructural abnormalities in lipid lamellae and disorganization of the stratum corneum, as in dogs and people, been reported in horses?
Yes – unclear if result of inflammation or primary impairment
Do horses with atopic dermatitis often develop secondary Staphylococcal infections, as dogs do, that lead to increased pruritus, folliculitis and hair loss?
Yes
Which pruritogenic mediators can stimulate pruritus, other than IL-31?
Histamine, proteases, substance P, opioids, neurotrophins, and other neuroactive peptide
Icelandic horses imported to Culicoides infested areas that do not develop IBH during their first summer of exposure show an increase in which Ig?
IgG5 - may be predictive of developing IBH the following year
Do Icelandic horses imported as foals or bred in Culicoides endemic areas show as high a prevalence as those imported later in life (> 50%)?
No – those born in Europe and USA show similar prevalence to other breeds e.g. 8-10% (Swedish-born Icelandic horses, Shetlands and Belgian Warmbloods)
What is the heritability of IBH?
- 08-0.36
0. 16 (Friesians), 0.24 (Dutch Shetlands) and 0.27 (Swedish-born Icelandic horses)
IBH mainly involves type I hypersensitivity - what are the key events in type I hypersensitivity sensitisation phase?
- IL-25, IL-33 and TSLP are released from injured epithelial cells inducing type 2 ILCs to produce IL-5 and IL-13
- APCs direct a Th2 response with product of IL-4 and IL-13
- B cells undergo class switching and produce allergen specific IgE that binds to high affinity FcεRI receptors on basophils and mast cells, leading to sensitization
When does the late phase reaction associated with a type I hypersensitivity reaction peak?
24 hours post exposure