Blood and immune: allergy and hypersensitivity

Question 1

major types of allergies (type 1 hypersensitivity)

Answer 1

• asthma
• allergic rhinitis (seasonal hayfever)
• skin eczema, urticaria (hives)
• insect allergies
• animal dander (animal proteins)
• drugs
• large food proteins (peanut, gluten)
• nickel (metal induced contact dermatitis)
• anaphylaxis (sytematic)

Question 2

type 1 hypersensitivity

Answer 2

FcE receptor on mast cells has high affinity to IgE antigen complexes. When IgE binds large complex antigens (like pollen), it triggers local mast cells to rupture and empty their granules.

Question 3

4 hypersensitivity classes

Answer 3

1. atopic allergy (IgE mediated), intermediate
2. complement mediated (medium)
3. serum sickness (immune complexes), medium
4. delayed type (DTH), slow response

Question 4

type II hypersensitivity example

Answer 4

involces FcR, complement and neutrophils
Rhesus baby: blood group antigen RhD, on surface of red blood cells. maternal antibodies developed to feta l RhD cause lysis of newborn RBCs

Question 5

alergic desensitisation

Answer 5

treat patient over 12-4 weeks with increasing doses of allergen. makes high affinity IgG that competes with IgE