allergies

Question 1

skin sensitisation theory

Answer 1

1. break in infant skin allows allergen to enter bloodstream and react with immune system
2. child does not have contact with allergen in GIT

if exposed to GIT, then recognised as food and not harmful

Question 2

hypersensitivity type 1

Answer 2

IgE antibodies trigger mast cells and basophils
histamines and cytokines released
immediate reaction

Question 3

hypersensitivity type 2

Answer 3

IgG and IgM activate complement system leading to direct damage to local cells

e.g. haemolytic disease of newborn

Question 4

hypersensitivity type 3

Answer 4

immune complexes accumulate and damage local tissues

e.g. SLE, HSP

Question 5

hypersensitivity type 4

Answer 5

cell mediated hypersensitivity by T cells

Question 6

gold standard test

Answer 6

food challenge testing

Question 7

Mx following exposure

Answer 7

antihistamines
steroids
IM adrenaline

close monitoring after allerigic reaction to ensure doesnt progress to anaphylaxis

Question 8

what is anaphylaxis caused by

Answer 8

T1 hypersensitivity reaction

Question 9

anaphylaxis: pathophys

Answer 9

IgE stimulates mast cells to rapidly release histamine and other pro-inflam chemicals

mast cell degranulation

Question 10

anaphylaxis: what differentiates it from non-anaphylxis allergic reactions

Answer 10

airway compromise

Question 11

anaphylaxis: Mx

Answer 11

IM adrenaline
antihistamines
steroids

observation after event as biphasic reactions can occur

Question 12

confirming anaphylaxis:

Answer 12

serum mast cell tryptase within 6hrs of event

Question 13

indications for epi-pen

Answer 13

• Hx anaphylaxis
• allergen cant be avoided
• allergic to high risk allergen
• idiopathic reaction
• asthma