CSIM 1.46 Case 44 Launch - A man who couldn't finish lunch. Allergic disease 1

Question 1

Define:

1) Hypersensitivity
2) Allergy
3) Anapylaxis

Answer 1

1) Objectively reproducible symptoms initiated by exposure to a defined stimulus at a dose tolerated by normal subjects
2) A hypersensitivity reaction initiated by immunologic mechanisms
3) Rapid-onset life-threatening hypersensitivity reaction involving breathing or circulatory problems

Question 2

Describe sensitisation

Answer 2

• The allergen is presented to the patient for the first time
  
  • An antigen from the allergen is taken up by a dendritic cell
  • The dendritic cell presents the allergen to an allergen-specific T cell
  • The T cell differentiates into a Th2 cell
  • The Th2 cell releases IL-4, IL-5 and IL-13, and activates its specific B cell
  • The B cell produces allergen-specific IgE
  • The IgE mounts on the surface of mast cells, where it ‘waits’ for the allergen to return
  • Mast cell degranulates if allergen returns

Question 3

Describe the components of a Type 1 hypersensitivity response

Answer 3

Early phase:

• Starts within minutes of exposure (

Question 4

What is atopy?

Answer 4

A syndrome characterized by a tendency to be “hyperallergic”. A person with atopy typically presents with one or more of the following:
• eczema (atopic dermatitis)
• allergic rhinitis (hay fever)
• allergic asthma.

Question 5

What is the atopic march?

Answer 5

The typical sequence of IgE atopic responses, and the order in which they manifest clinically as you increase in age:

1) Eczema
2) Food allergy
3) Rhinitis
4) Asthema

IMG 115

Question 6

What is:

1) Type 1 hypersensitivity
2) Type 2 hypersensitivity
3) Type 3 hypersensitivity
4) Type 4 hypersensitivity

Answer 6

1) Hypersensitivity involving IgE antibodies on the surface of mast cells binding to soluble antigen
2) IgG binds to antigen being presented by a cell activating the complement system, causing host cell lysis
3) IgG binds to circulating antigen, to form a circulating immune complex, which becomes deposited throughout the body, provoking an inflammatory reaction
4) Antigen interacts with antigen-specific T cell which release inflammatory and cytotoxic substances, causing tissue injury inflammation

Question 7

What is type 4 hypersensitivity also known as

Answer 7

Delayed or cell-mediated hypersinsitivity

Question 8

What type of hypersensitivity is responsible for:

1) Contact dermatitis?
2) Allergic rhinitis?
3) Asthema?
4) Penicillin allergies?
5) Serum sickness?
6) Coeliac disease?

Answer 8

1) Type 4
2) Type 1
3) Type 1
4) Type 2
5) Type 3
6) Type 4

Question 9

What is the mantoux test?

What type of hypersensitivity type is this if positive?

Answer 9

A test to see if a patient has had previous exposeure to Mycobacterium tuberculosis
• Intradermal injection of protein derivative of Mycobacterium tuberculosis is injected
• The area is marked
• Patient is left for 72 hours
• If the patient has been xposed before, the patient will create an inflammatory response
• The area of induration (not the erythema) is measured, is >15mm then it is a positive result (IMG 16)

Type 4

Question 10

Describe the indications for diagnosing anaphylaxis

Answer 10

Acute onset of an illness with involvement of the skin, mucosal tissue or both PLUS respiratory compromise or reduced BP (30% decrease from baseline)/perfusion of end-organs

Question 11

What is urticaria?

Answer 11

Superficial swelling, causing a raised lesion surrounded in erythema (IMG 117)

Question 12

What is angioedema?

Answer 12

Swelling of skin or mucosal tissues which is often red and itchy and often appears on lips

Question 13

What drugs can increase chance of anaphylaxis?

Answer 13

• NSAIDs
  
  • ACE inhibitors
  • Beta-blockers

Question 14

How is anaphylaxis managed?

Answer 14

• Lye patient down (BP)
  
  • Adrenaline IM
  • Nebulised Salbutamol/Adrenaline/Budesonide
  • Connect to oxygen
  • IV fluids
  • Chlorphenamine and hydrocortisone (to control late phase)