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
When in the menstrual cycle have urticaria been reported?
Luteal phase- progesterone
26
What are the following associated with a) cholinergic urticaria b) adrenergic urticaria
a) heat and sweating | b) stress
27
What 3 drug classes are recommended in the treatment of acute urticaria
1) Antihistamines 2) Rantidine (H2 antagonist) 3) Montelukast (leukotriene antagonist)
28
Which antihistamine is older and more sedative
Chlorphenamine
29
What is recommended for chronic urticaria
Omalizumab (mab to IgE)
30
Define angioedema
Swelling of the subcutaneous tissues due to inflammation
31
How do you know if angioedema is allergic
- Accompanied by urticaria | - Part of anaphylaxis/ anaphylactoid reaction
32
Drug cause of angioedema
ACEi
33
Briefly describe hereditary angioedema Type 1
Deficiency of C1 esterase inhibitor, which usually restrains bradykinin pathway
34
Briefly describe hereditary angioedema part 2
Mutation of C1 esterase inhibitor
35
Briefly describe hereditary angioedeme part 3
Mutation of Factor XII gene which initiates bradykinin pathway
36
What are some causes of an acquired C1 esterase inhibitor deficiency
- Autoimmune disease - Haem malignancy - Infections: Hep B/C, Helicobacter
37
How can you identify idiopathic angioedema
Normal levels of C1 esterase inhibitor
38
How do you treat angioedema if it is a) allergic b) C1 inhibitor deficiency c) Idiopathic
a) As for urticaria and anaphylaxis b) Anabolic steroids, tranexamic acid, C1 inhibitor c) Tranexamic acid
39
MoA icatibant
Inhibits bradykinin pathway
40
What type of hypersensitivity reaction causes allergic conjuctivities, rhinitis and sinusitis
Type 1 | IgE mediatedd
41
How is allergic conjunctivitis, rhinitis, sinusitis diagnosed?
HISTORY | - Skin prick tests/ specific IgE confirmatory
42
Treatment for allergic conjunctivitis, rhinitis, sinusitis (4)
- Allergen exclusion - Topical or systemic antihistamines - Topical mast cell stabilisers - Topical steroids
43
MoA of disodium chromoglycate
Topical mast cell stabiliser
44
Define atopy
Genetic predisposition to make IgE antibodies against common environmental antigens (associated with dermatitis, asthma etc.)
45
Describe the presentation of atopic dermatitis
- Dry, cracked, itchy, raised, weeping lesions | - Initially on extensor surfaces, then flexutres, also cheeks
46
What is often raised in atopic dermatitis
IgE (*81 normal range)
47
What organism often causes infection in areas affected by atopic dermatitis
Staphylococcal infection
48
Symptoms of aspirin sensitivity
Angioedema | Triad: sinusitis, nasal polyps, asthma
49
What allergen can enhance the ability of other allergens to cause anaphylaxis
Aspirin
50
What hypersensitivity reaction type is involved in oral allergy syndrome (food allergy)
Type 1
51
Describe the immediate presentation of food allergy
Itching and local swelling in the oropharynx within minutes of eating food. Rarely may progress to urticaria and angioedema of face--> anaphylaxis
52
How do you treat eosinophilic gastropathy
Steroids
53
Gut symptoms of oral allergy
Abdo pain diarrhoea, vomiting
54
Which 2 allergies are common in children and often go away later on
Milk and egg
55
Where is latex present
- Gloves - Medical products - Condoms
56
Signs and symptoms of latex allergy
- Contact urticaria - Rhino-conjunctivitis - Asthma - Angioedema - Anaphylaxis
57
Diagnosis in latex allergy
Skin prick tests and specific IgE tests
58
What type of hypersensitivity reaction is serum sickness
III
59
When does serum sickness occur?
After an infusion of serum sickness
60
Features of serum sickness
Fevers, poly-arthritis, vasculatis, lymphadenopathy
61
What is DRESS syndrome
Drug reactions with Eosinophils and systemic symptoms.
62
When does DRESS syndrome occur
After several weeks
63
What hypersensitivity reaction is involved in extrinsic allergic alveolitis
Type III
64
What causes extrinsic allergic alveolitis
Inhaled foreign antigens, occupational exposure
65
What are the symptoms of extrinsic allergic alveolitis, and when do they occur
6 hours after exposure, peaking at 24 | SOB, fever, cough
66
What type of hypersensitivity reaction is a contact hypersensitivity
IV
67
What is erythema multiforme? | What are the key features?
Hypersensitivity reaction triggered by infection | Features- target lesions initially on back of hands/ feet. Pruitis
68
What can cryglobulins cause
Angioedema
69
What are C3, C4, C1q, C2, anti-C1q antibodies involved in
Complement cascade
70
C3 and C4 are low in...
Systemic lupus erythema