Immu 5: Allergy Flashcards
(36 cards)
Name 1 cytokine released from damaged epithelium secondary to exposure to an allergen/worm ?
TSLP
describe the Th2 mediated response
- stressed/damaged epithelium releases signalling cytokines eg TSLP
- these cytokines act on Th2 cells, Th 9 cells and ILC2 cells
- promoting the selectionof IL4, IL5, IL13
- these act on eosinophils and basophils
- TSLP and other cytokines also activate follicular Th2 cells which releases IL4
- IL4 stimulated B cells to produce IgE and IgG4
- skin dendritic cells promote the secretion of Th2 cytokines
Which T cells are involved with allergy response ?
Th2 cells
Which T helper cells recognise pathogen structures like PAMPs? (2)
Th1 and Th17
List 3 important cytokines released by Th2 cells in an allergic response ?
IL-4
IL-5
IL-13
3 lymphocyte cell types involved in initial allergen response
- Th2 cells
- Th9 cells
- ILC2 cells
Which cytokine released by Th2 cells is considered the master switch that causes Isotype switching of B cells to IgE ?
IL-4
What protein on the surface of dendritic cells signals to naïve T cells in food allergy?
OX40
How do allergens/worms cause Histamine and leukotriene release ?
What is the effect of these mediators?
They cause cross linking of IgE receptor on mast cells, which causes release of Histamine, leukotriene and prostaglandins
Oral vs skin / resp exposure to allergen
- Oral: IgG and IgA mediated sensitisation
- Skin/resp: IgE sensitisation
what happens when an allergen is ingested through the oral route
T regs derived from the GI mucose will inhibit IgE sythesis to keep the immune system in balance
Which allergies develop in infants ? (2)
Atopic dermatitis
Food allergies - milk, egg, nuts
Which allergies develop in children ?
Asthma
allergic Rhinitis
Which allergies tend to develop in adults ? (4)
Drug allergies
Oral allergy syndrome
Occupational allergies
Bee sting allergy
Name a bio marker for anaphylaxis?
What is peak concentration?
What releases this marker?
Mast cell tryptase
- is useful in anaesthetics to rule out anaphylaxis when there is acute hypotension and rash
Peak concentration = 1-2 hours after exposure
Systemic degranulation of mast cells during anaphylaxis results in increased serum tryptase
What is the gold standard test for food and drug allergy ?
Challenge tests
- can be done in clinic to see if food or drugs promotes an allergic response
Give 3 different types of anaphylaxis other than IgE ?
IgG- e.g monoclonal antibodies
Complement- dialysis membranes
Pharmacological- aspirin and NSAIDS
What is a cause of Throat swelling which mimics anaphylaxis (rare)?
C1 inhibitor deficiency
What is the most important treatment of Anaphylaxis ?
IM adrenaline (outer aspect of thigh)
how is anaphylaxis managed
- IM ADRENALINE
- 100% oxygen
- fluid replacement
- inhaled bronchodilators (salbutamol)
- hydrocortisone 100mg IV
- chlorpheniramine 10mg IV
What is a cause of delayed food induced anaphylaxis ?
Beef, pork,lamb
Tick bites
Gelatine in vaccines can do it as well
what are the clinical features of an IgE mediated response
- minutes to hours after exposure
- angioedema, urticaria, flushing, itching, cough, SOB, nasal congestion, wheeze, red watery eyes, d+v, hypotension
- usually at least 2 organ systems involved
- symptoms are reproducible
- allergic symptoms can be triggered by cofactors
how can we investigate allergic disease
- skin prick and blood test
- lab measurements of allergen-specific IgE
- component-resolved diagnosis
- basophil activation test
- challenge test
- during an acute episode - serial mast cell tryptase
- blood and/or urine antihistamine
Describe specific IgE sensitisation test
What is a +ve test?
Rule with antihistamines before doing this test?
Skin prick and blood tests
- higher concentration = more symptoms
- higher affinity to target = increased risk
- Measure the local wheal and flare response to controls and allergens
+ve test = wheal ≥ 3mm greater than the negative control
Antihistamines: stop these 48 hrs before test (do serum IgE levels if they cannot stop this for whatever reason)
