Allergies Flashcards

1
Q

Define hypersensitivity

A

Damage to a patient caused by the immune system

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2
Q

Define allergy

A

A type 1 hypersensitivity reaction in response to foreign antigens

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3
Q

What is involved in a type 1 hypersensitivity reaction?

A

IgE Mast Cells

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4
Q

What is involved in a type 2 hypersensitivity reaction?

A

Autoantibodies

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5
Q

What is involved in a type 3 hypersensitivity reaction?

A

Immune mediated complexes

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6
Q

What is involved in a type 4 hypersensitivity reaction?

A

T cells

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7
Q

What is involved in a type 5 hypersensitivity reaction?

A

Upregulation (eg Graves)

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8
Q

What is anaphylaxis, and briefly, what happens within anaphylaxis? What is released?

A

A type 1 hypersensitivity reaction

  • Degranulation and activation of mast cells and basophils
  • Release of leukotrienes and histamine
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9
Q

Signs and Symptoms of anaphylaxis?

A
Syncope
Bronchospasm (wheeze)
Urticaria (red, itchy rash)
Angioedema (swelling with fluid in subcut tissue)
Abdo pain
Vomiting
Diarrhoea
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10
Q

What test is used to diagnose anaphylaxis?

A

Tryptase

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11
Q

Differentials for anaphylaxis?

A
PE
MI
Hyperventilation
Hypoglycaemia
Vasovagal
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12
Q

Describe the short term treatment of anaphylaxis

A
  • IM Adrenaline
  • Oxygen 100%
  • IV fluids
  • IV glucocorticosteroids and antihistamines
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13
Q

What is the long term treatment of anaphylaxis?

A
  • Identify antigen responsible
  • Avoid antigen
  • Can use prophylactic antihistamine
  • Carry adrenaline injection device
  • Sometimes, densensitisation
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14
Q

Define anaphylactoid reaction?

A

The direct or indirect activation of mast cells without IgE

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15
Q

What are some causes of anaphylactoid reactions

a) drugs
b) food
c) physical stimuli

A

a) Vancomycin, opiates, NSAIDS
b) Strawberries
c) exercise, cold, truama

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16
Q

Are anaphylactoid reactions tryptase positive

A

Yes

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17
Q

Define scromboid

A

Massive ingestion of histamine from decayed mackrel and other oily fish.

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18
Q

Are scromboid reactions tryptase positive?

A

No, as mast cells not involved

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19
Q

What is urticaria?

A

Raised, itchy, erythermous rash

Inflammation within the dermis

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20
Q

Name allergic causes of urticaria?

Usually acute or chronic?

A
  • Anaphylaxis, anaphylacoid and scromboid (drugs, food and arthropod venoms)
  • Local injections of antigens such as bites and scratches
  • Direct contact: latex gloves, grass

Usually acute

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21
Q

Describe the autoimmune causes of urticaria

A
Autoantibodies to Fc- Epsilon receptors on mast cells/ basophils
SLE
Vasculitis
Injected serum/ blood products
Type 3 hypersensitivity (usually)
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22
Q

What infections can cause urticaria

A

Hep B
H. Pylori
Lymes Disease

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23
Q

What deficiencies can cause urticaria

A

B12

Folate

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24
Q

Name a mast cell disorder that cause cause urticaria

A

Urticaria pigmentosa

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25
Q

When in the menstrual cycle have urticaria been reported?

A

Luteal phase- progesterone

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26
Q

What are the following associated with

a) cholinergic urticaria
b) adrenergic urticaria

A

a) heat and sweating

b) stress

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27
Q

What 3 drug classes are recommended in the treatment of acute urticaria

A

1) Antihistamines
2) Rantidine (H2 antagonist)
3) Montelukast (leukotriene antagonist)

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28
Q

Which antihistamine is older and more sedative

A

Chlorphenamine

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29
Q

What is recommended for chronic urticaria

A

Omalizumab (mab to IgE)

30
Q

Define angioedema

A

Swelling of the subcutaneous tissues due to inflammation

31
Q

How do you know if angioedema is allergic

A
  • Accompanied by urticaria

- Part of anaphylaxis/ anaphylactoid reaction

32
Q

Drug cause of angioedema

A

ACEi

33
Q

Briefly describe hereditary angioedema Type 1

A

Deficiency of C1 esterase inhibitor, which usually restrains bradykinin pathway

34
Q

Briefly describe hereditary angioedema part 2

A

Mutation of C1 esterase inhibitor

35
Q

Briefly describe hereditary angioedeme part 3

A

Mutation of Factor XII gene which initiates bradykinin pathway

36
Q

What are some causes of an acquired C1 esterase inhibitor deficiency

A
  • Autoimmune disease
  • Haem malignancy
  • Infections: Hep B/C, Helicobacter
37
Q

How can you identify idiopathic angioedema

A

Normal levels of C1 esterase inhibitor

38
Q

How do you treat angioedema if it is

a) allergic
b) C1 inhibitor deficiency
c) Idiopathic

A

a) As for urticaria and anaphylaxis
b) Anabolic steroids, tranexamic acid, C1 inhibitor
c) Tranexamic acid

39
Q

MoA icatibant

A

Inhibits bradykinin pathway

40
Q

What type of hypersensitivity reaction causes allergic conjuctivities, rhinitis and sinusitis

A

Type 1

IgE mediatedd

41
Q

How is allergic conjunctivitis, rhinitis, sinusitis diagnosed?

A

HISTORY

- Skin prick tests/ specific IgE confirmatory

42
Q

Treatment for allergic conjunctivitis, rhinitis, sinusitis (4)

A
  • Allergen exclusion
  • Topical or systemic antihistamines
  • Topical mast cell stabilisers
  • Topical steroids
43
Q

MoA of disodium chromoglycate

A

Topical mast cell stabiliser

44
Q

Define atopy

A

Genetic predisposition to make IgE antibodies against common environmental antigens (associated with dermatitis, asthma etc.)

45
Q

Describe the presentation of atopic dermatitis

A
  • Dry, cracked, itchy, raised, weeping lesions

- Initially on extensor surfaces, then flexutres, also cheeks

46
Q

What is often raised in atopic dermatitis

A

IgE (*81 normal range)

47
Q

What organism often causes infection in areas affected by atopic dermatitis

A

Staphylococcal infection

48
Q

Symptoms of aspirin sensitivity

A

Angioedema

Triad: sinusitis, nasal polyps, asthma

49
Q

What allergen can enhance the ability of other allergens to cause anaphylaxis

A

Aspirin

50
Q

What hypersensitivity reaction type is involved in oral allergy syndrome (food allergy)

A

Type 1

51
Q

Describe the immediate presentation of food allergy

A

Itching and local swelling in the oropharynx within minutes of eating food.
Rarely may progress to urticaria and angioedema of face–> anaphylaxis

52
Q

How do you treat eosinophilic gastropathy

A

Steroids

53
Q

Gut symptoms of oral allergy

A

Abdo pain diarrhoea, vomiting

54
Q

Which 2 allergies are common in children and often go away later on

A

Milk and egg

55
Q

Where is latex present

A
  • Gloves
  • Medical products
  • Condoms
56
Q

Signs and symptoms of latex allergy

A
  • Contact urticaria
  • Rhino-conjunctivitis
  • Asthma
  • Angioedema
  • Anaphylaxis
57
Q

Diagnosis in latex allergy

A

Skin prick tests and specific IgE tests

58
Q

What type of hypersensitivity reaction is serum sickness

A

III

59
Q

When does serum sickness occur?

A

After an infusion of serum sickness

60
Q

Features of serum sickness

A

Fevers, poly-arthritis, vasculatis, lymphadenopathy

61
Q

What is DRESS syndrome

A

Drug reactions with Eosinophils and systemic symptoms.

62
Q

When does DRESS syndrome occur

A

After several weeks

63
Q

What hypersensitivity reaction is involved in extrinsic allergic alveolitis

A

Type III

64
Q

What causes extrinsic allergic alveolitis

A

Inhaled foreign antigens, occupational exposure

65
Q

What are the symptoms of extrinsic allergic alveolitis, and when do they occur

A

6 hours after exposure, peaking at 24

SOB, fever, cough

66
Q

What type of hypersensitivity reaction is a contact hypersensitivity

A

IV

67
Q

What is erythema multiforme?

What are the key features?

A

Hypersensitivity reaction triggered by infection

Features- target lesions initially on back of hands/ feet. Pruitis

68
Q

What can cryglobulins cause

A

Angioedema

69
Q

What are C3, C4, C1q, C2, anti-C1q antibodies involved in

A

Complement cascade

70
Q

C3 and C4 are low in…

A

Systemic lupus erythema