allergy and hypersensitivity

Question 1

Give examples of clinical indications of allergy

Answer 1

epithelial - eczema, itching, reddening
XS mucus production
airway constriction
abdominal bloating, vomiting, diarrhoea
anaphylaxis

Question 2

Define allergy

Answer 2

abnormal response to harmless foreign material

Question 3

What is atopy?

Answer 3

a hereditary predisposition to the development of immediate hypersensitivity reactions against common environmental antigens

Question 4

Give examples of allergic diseases/ causes of allergy

Answer 4

Rhinitis, anaphylaxis, asthma, dermatitis, eczema, insect venom, food allergies, medication

Question 5

Give examples of allergens

Answer 5

Pollen, house dust mites, animal fur, nickel, foods

Question 6

Which cells are involved in allergy?

Answer 6

mast, eosinophil, basophil, lymphocytes (Th2), dendritic cells (APC), smooth muscle, fibroblasts, epithelial, neurones (coughing and sneezing)

Question 7

IgE has a short half life. T or F

Answer 7

True as it is only 2.5 days

Question 8

IgE fixes complement. T or F

Answer 8

F

Question 9

What needs to happen to the IgE receptors before a cellular response occurs

Answer 9

cross-linking

Question 10

What is the low affinity IgE receptor called?

Answer 10

FceRII

Question 11

Which cells express low-affinity IgE receptors?

Answer 11

B cells, T cells, monocytes, eosinophils, platelets and neutrophils

Question 12

What is the function of the low-affinity IgE receptor?

Answer 12

1. regulates IgE synthesis
2. triggering of cytokine release by monocytes
3. antigen presentation by cells

Question 13

What are the three major cell types that express high affintiy IgE receptor?

Answer 13

1. eosinophils
2. mast cells
3. basophils

Question 14

What protein do mast cells require?

Answer 14

c-kit

Question 15

What preformed compounds to mast cells contain?

Answer 15

1. histamine
2. chemotactic factors
3. proteases
4. proteoglycans

Question 16

What lipid derived mediators do mast cells contain?

Answer 16

leukotrienes
prostaglandin D2
platelet activating factor

Question 17

What type of cell do mast cells activate with their chemokines?

Answer 17

eosinophils (macrophages nd neutrophils)

Question 18

What factors activate mast cells?

Answer 18

allergens 
bacterial/viral antigens 
phagocytosis of enterobacteria
cold/mechanical defomation
aspirin, latex, proteases

Question 19

Which T cells response is activated by mast cells?

Answer 19

Th2 (IL-4,5,10)

Question 20

What are the characterisitics of an allergen?

Answer 20

weak PAMPs
nasal/skin delivery
low dose

Question 21

Can you get allergic responses without IgE bind initially?

Answer 21

Yes, some allergens can stimulate the production of IL-4 from mast cells. IL-4 leads to isotype switching in B cells to IgE production. The IgE then activates mast cells - cycle

Question 22

Give cardiovascular changes in anaphylaxis

Answer 22

vasodilation
increased vascular permeability
lower BP

Question 23

Give respiratory changes in anaphylaxis

Answer 23

bronchial smooth muscle contraction

mucus

Question 24

Give dermatological changes in anaphylaxis

Answer 24

rash

swelling

Question 25

Give GI symptoms in anaphylaxis

Answer 25

pain | vomiting

Question 26

Name the 6 treatment strategies for allergic disease

Answer 26

1. avoid the allergen 2. desensitise to allergen 3. prevent IgE production 4. prevent IgE interaction with receptor 5. prevent mast cell activation 6. inhibit mast cell products

Question 27

Give two routes of desensitisation

Answer 27

sublingual | subcutaneous

Question 28

Give ways to prevent IgE production

Answer 28

1. suppression of Th2 responses - allergens fused to the cholera toxin 2. suppressive cytokines eg IL12 that reduces eosinophilia and IL-18 that reduces IgE production 3. blocking cytokines - IL-4 antagonist 4. targeting CD23 associated with low affinity IgE receptors to reduce IgE levels

Question 29

Give a drug to block binding of IgE to its high affinity receptor

Answer 29

Omalizumab

Question 30

Give disadvantages of Omalizumab

Answer 30

very high cost increase in cancer incidence anaphylaxis not recommended where intestinal parasites are present

Question 31

Give examples of two anti-cytokine antibodies permitted by NICE

Answer 31

IL-5 antibodies | IL-2 antibodies

Question 32

Give methods to prevent mast cell activation

Answer 32

1. membrane stabilisers 2. beta-2-agonists (increase camp leading do bronchodilation) 3. channel blockers 4. signalling inhibitors 5. glucocorticoid - inhibit gene transcription

Question 33

Name some mast cell product inhibitors

Answer 33

1. histamine receptor antagonists 2. leukotriene and prostaglandin antagonists 3. tryptase inhibitors 4. protease-activated receptor antagonists