Allergy

Question 1

What happens in allergy?

Answer 1

Binding of allergens to preformed igE antibodies on the surface of mast cells and basophils

Question 2

IgE binds to

Answer 2

FcepsilonR1

Question 3

If you have more than one IgE bounds to allergen then?

Answer 3

Clustering of receptors , intracellular portion of receptor is phosphorylated, which leads to intracellular cascade and cellular activation.

This in turn causes mast cell to degranulation releasing histamine, tryptase

Question 4

Leukotrienes are produced from/

Answer 4

Arachidonic acid being converted by lipoxygenase

Question 5

Membrane phospholipids are converted to arachidonic acid by?

Answer 5

Phospholipase a2, which is created through inflammation, mast cell activation

Question 6

What are effects of mast cell activation?

Answer 6

Gastro- increased fluid secretion/ peristalsis

Airway- decreased diameter and. Increased mucus secretion

Blood v- increase blood flow, permeability

Question 7

Anaphylaxis causes?

Answer 7

Generalised vasodilatation, and fluid loss from circulation to tissue as a result of histamine release

Question 8

Signs of anaphylaxis?

Answer 8

Hives, angiodema, vomiting diarrhoea, hypotension, vasodilatation, laryngeal oedema bronchocondtriction

Question 9

Most common type of food allergy?

Answer 9

Oral allergy syndrome

Oral itching- mainly rosacea fruits

Question 10

Changes in asthmatic airway?

Answer 10

Thickened basement membrane and smooth muscle hyperplasia

Question 11

Late phase shows?

Answer 11

Infiltration with inflammatory cells, CD4 T cells, eosinophils, and mast cells

Starts 4 hours after early phase and finishes within 4 hours

Question 12

Th1 secrete

Answer 12

IFN g

Question 13

TH2 secrete?

Answer 13

Il 4, 5 9 and 13

Question 14

Th17 secrete?

Answer 14

Il 17, for defence against bacteria and fungi

Question 15

TH2 responses are needed in allergy?

Answer 15

Il4- b class switching to igE
IL4 and 13 promote mucus hypersecretion
Il5 for eosinophils survival
Il9 recruits mast cells

Question 16

Hygiene hypothesis?

Answer 16

Small family size, low infection burden, good sanitation,

So more likely to develop allergic disease

Question 17

In low hygiene levels immunity is skewed to?

Answer 17

TH2 to th1

Induce production of regulatory T cells

Question 18

Leap study?

Answer 18

High risk infants to peanuts
At 6 months randomised to regular consumption or avoidance
Children have greater allergy in avoidance
Theory is they meet it through the skin, increase in TH2
But in gut, t regs

Question 19

Skin testing?

Answer 19

Drops of allergen, top layers of epidermis punctured with lancet
Wheal with flare in 15 mins

Question 20

Radioallergosorbant assay, now by Elisa?

Answer 20

Allergen on the plastic add in the serum. Antibodies igE sensitised bind to allergens.
Secondary antibody anti iGE to detect with a marker

Question 21

Symptoms relievers?

Answer 21

Act on pathways

B2 agonist salbutamol- b2 adrenoreceptors cause smooth muscle relaxation

Epinephrine- oppose vasodilatation and bronchoconstiction

Nasal decongestant- oxymetazoline
Act on alpha 1 adrenoreceptors, cause vasoconstriction

Question 22

Direct affecting pathway

Answer 22

Leukotriene receptor antagonist (only used for asthma)
H1 antihistamine
Mast cell stabilisers (for eye drops rhinitis)

Question 23

Example of mast cell stabiliser

Answer 23

Sodium cromoglycate

Topical use only
Short half life

Question 24

Leukotriene receptor antagonist example

Answer 24

Montekulast, beneficial in chronic asthma

Question 25

Monoclonal antibody against igE?

Answer 25

Omalizumab atopic asthma

Question 26

Allergen specific immunotherapy works how?

Answer 26

Reduce TH2 responses Induced allergen specific igG antibodies Reduction i mast cell responsiveness Reduced allergen specific igE levels