Hypersensitivity

Question 1

Briefly describe Type I allergic reactions

Give examples

Answer 1

rapid, 30 mins
IgE mediated, immediate type hypersensitivity
Degranulation of mast cells
e.g. allergic rhinitis, allergic asthma, urticarial

Question 2

Briefly describe Type II allergic reactions

Give examples

Answer 2

days
cytotoxic reaction (complement lysis, ADCC)
e.g. drug allergies

Question 3

Briefly describe Type III allergic reactions

Give examples

Answer 3

6-8 hours
immune complex reaction (complement activation)
e.g. allergic vasculitis

Question 4

Briefly describe Type IV allergic reactions

Give examples

Answer 4

48-72 hours
T-cell mediated, delayed type hypersensitivity
e.g. allergic contact dermatitis

Question 5

What are the general properties of antigens?

Answer 5

small, 15-40,000Mw proteins 
resistant to proteolytic degradation
long lasting in environment
low dose of allergen
mucosal exposure
often proteases
most promote a Th2 response