Immunology 6 - Allergy Flashcards
What is the difference in CD4 T cell response between microbial recognition and allergen recognition?
Microbe: PAMP is recognised –> Th1 and Th17 response
Allergen: functional change is recognised (eg tissue damage) –> Th2 response
How does Th2 activation cause mast cell degranulation?
Th2 secretes IL4 IL4 activates B cells to produce IgE IgE causes mast cells to degranulate and secrete: - prostaglandins - leukotrienes - histamines
Why does atopic dermatitis predispose to allergic sensitisation?
Skin exposure more likely to lead to IgE response than oral exposure
Which interleukin is most important in Th2 cell responses?
IL4
Why do filagrin mutations increase risk of allergic disease?
Increase risk of atopic dermatitis which increases allergen exposure
What represents a positive result in a skin-prick allergy test?
Wheal >3mm (path lecture)/ >2mm (path guide) bigger than control
Recall 2 limitations of skin prick allergy testing
- Necessary for diagnosis but is insufficient alone
2. Result does not predict severity of reaction
What can component/ molecular allergy testing be useful for?
For nuts, detection of storage protein is indicative of a stronger reaction
For wheat, detection of omega-5-gliadin is indicative of a stronger reaction
What is a measurement of mast cell tryptase used for?
Biomarker for anaphylaxis that peaks 1-2 hours following a reaction
Useful if diagnosis of anaphylaxis is not clear
What is the gold standard method of allergy testing?
Challenge tests
How should an allergy challenge test be performed?
Increase volume of allergen and measure response - it is the gold standard for food allergy diagnosis (done as a double blind)
Describe the symptoms of the oral allergy syndrome
Symptoms of allergy limited to mouth
Common allergens = birch pollen + rosacea fruit + ragweed + melons + mugwort + celery (due to cross reactivity)
Recall some foods that may trigger the Latex Food Syndrome?
Chestnut Avocado Banana Potato Tomato Papaya Kiwi Aubergine Mango Wheat Melon Latex
What are the positive and negative controls used in skin prick testing?
Positive: histamine
Negative: diluent
Recall the management of anaphylaxis in adults
Elevate legs 100% oxygen IM adrenaline 500 mcg Inhaled bronchodilators Hydrocortisone 200mg IV Chlorphenamine 20mg IV IV fluids Seek help
