Allergies Flashcards

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1
Q

define hypersensitivity

A

immune response that causes collateral damage to self due to an exaggeration of normal immune mechanisms

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2
Q

what is type 1 hypersensitivity mediated by?

A

IgE

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3
Q

what is type 2 hypersensitivity mediated by?

A

IgG

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4
Q

what is type 3 hypersensitivity mediated by?

A

immune complex

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5
Q

what is type 4 hypersensitivity mediated by?

A

T cell mediated

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6
Q

when do allergic reactions occur?

A

when a person’s immune system reacts to normally harmless substances in the environment

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7
Q

what is the hygiene hypothesis?

A

we live in a society so clean that our body is not used to many substances which we used to be exposed to regularly

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8
Q

when will a type 1 allergy occur?

A

immediately (within minutes - 2 hours after exposure)

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9
Q

what are the routes of exposure for type 1 allergies?

A

skin contact
inhalation
ingestion
injection

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10
Q

what aspects of the history would make you suspect a type 1 allergy?

A

consistent reaction with every exposure

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11
Q

what will a type 1 allergy lookalike clinically?

A
  • urticaria (v itchy)
  • angioedema
  • wheezing/asthma
  • anaphylaxis
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12
Q

what investigations would you do for a type 1 allergy?

A
  • specific IgE test
  • skin prick testing
  • challenge testing
  • serum mast cell tryptase level (during anaphylaxis)
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13
Q

how would you manage a type 1 allergy?

A
  • allergen avoidance
  • anti-histamines
  • anti-inflammatory (corticosteroids)
  • adrenaline autoinjector
  • mast cell stabilisers (sodium cromoglycate)
  • immunotherapy
  • media alert bracelet
  • information & education
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14
Q

when does a type 4 allergy present?

A

typically after 24-48 hours

delayed hypersensitivity

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15
Q

give an example of a type 4 allergy seen in dermatology

A

allergic contact dermatitis

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16
Q

name some common allergens that cause a type 4 allergy

A
  • nickel
  • thiuram in nitrile gloves
  • colophony in elastoplast
  • fragrance in deodorants
  • chromate in leather
  • garlic
  • PDP in henna tattoos
  • diethylthiourea (wrist splints)
  • dermabond in surgical glue
  • english Ivy
  • gold
17
Q

when are patch tests read?

A

at 48 hours & 96 hours

18
Q

why are readings taken at both 48 & 96 hours?

A

type 1 allergies are delayed so should only be seen at 96 hours

19
Q

what is irritant contact dermatitis?

A

non-immunological process, contact with agents that abrade, irritate & traumatise skin directly

20
Q

give 2 examples of irritant contact dermatitis?

A
  • nappy rash

- lip lick dermatitis

21
Q

how are allergies managed?

A
  • allergen/irritant avoidance or minimisation
  • emollients
  • topical steroids
  • UV phototherapy
  • immunosuppressants