Allergy

Question 1

What are mast cells stimulated by?

Answer 1

• Surface IgE binding antigen.
• Complement activation: C5a, C3a.
• Nerves: axon reflex sensory nerves, Substance P.
• Direct stimulation.

Question 2

What substance is raised in anaphylaxis?

Answer 2

Tryptase (and D dimers)

Question 3

What are anaphylactoid reactions?

Answer 3

Direct/indirect activation of mast cells without IgE

Question 4

What are the common causes of anaphylactoid reactions?

Answer 4

o Drugs – opiates, vancomycin, anaesthetics, NSAIDs

o Foods: strawberries

Question 5

What is hereditary angioedema?

Answer 5

Episodes of severe swelling of the subcutaneous tissues, associated with deficiency of C1 esterase inhibitor (type 1 and 2) or mutation of factor XII gene (type 3)

Question 6

What is the treatment of angioedema?

Answer 6

Anabolic steroids or tranexamic acid

Question 7

What might cause acquired C1 esterase inhibitor deficiency?

Answer 7

Autoimmune disease, Hep B/C, helicobacter –> angioedema

Question 8

Define ‘atopy’

Answer 8

The genetic predisposition to make IgE antibody against common environmental antigens. Associated with hayfever, childhood asthma and atopic dermatitis