Allergy Flashcards

1
Q

What happens in allergy?

A

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

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2
Q

IgE binds to

A

FcepsilonR1

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3
Q

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

A

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

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4
Q

Leukotrienes are produced from/

A

Arachidonic acid being converted by lipoxygenase

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5
Q

Membrane phospholipids are converted to arachidonic acid by?

A

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

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6
Q

What are effects of mast cell activation?

A

Gastro- increased fluid secretion/ peristalsis

Airway- decreased diameter and. Increased mucus secretion

Blood v- increase blood flow, permeability

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7
Q

Anaphylaxis causes?

A

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

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8
Q

Signs of anaphylaxis?

A

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

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9
Q

Most common type of food allergy?

A

Oral allergy syndrome

Oral itching- mainly rosacea fruits

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10
Q

Changes in asthmatic airway?

A

Thickened basement membrane and smooth muscle hyperplasia

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11
Q

Late phase shows?

A

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

Starts 4 hours after early phase and finishes within 4 hours

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12
Q

Th1 secrete

A

IFN g

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13
Q

TH2 secrete?

A

Il 4, 5 9 and 13

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14
Q

Th17 secrete?

A

Il 17, for defence against bacteria and fungi

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15
Q

TH2 responses are needed in allergy?

A

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

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16
Q

Hygiene hypothesis?

A

Small family size, low infection burden, good sanitation,

So more likely to develop allergic disease

17
Q

In low hygiene levels immunity is skewed to?

A

TH2 to th1

Induce production of regulatory T cells

18
Q

Leap study?

A

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

19
Q

Skin testing?

A

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

20
Q

Radioallergosorbant assay, now by Elisa?

A

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

21
Q

Symptoms relievers?

A

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

22
Q

Direct affecting pathway

A

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

23
Q

Example of mast cell stabiliser

A

Sodium cromoglycate

Topical use only
Short half life

24
Q

Leukotriene receptor antagonist example

A

Montekulast, beneficial in chronic asthma

25
Q

Monoclonal antibody against igE?

A

Omalizumab atopic asthma

26
Q

Allergen specific immunotherapy works how?

A

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