Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Respiratory: Immunology > Hypersensitivity Diseases > Flashcards

Hypersensitivity Diseases Flashcards

1
Q

What are the consequences of immune recognition?

A
  • Intened destruction of the antigen

* Incidental tissue damage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are hypersensitive reactions?

A

Immune response that results in bystander damage to the self - usually an exaggeration of normal immune mechanisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What diseases involve hypersensitivity?

A

Allergy and autoimmunity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are classifications of hypersensitivity reactions?

A
  • Type I - immediate hypersensitivity
  • Type II - direct cell killing
  • Type III - immune complex mediated
  • Type IV - delayed type hypersensitivity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What type of hypersensitivity reaction is involved in allergic disease?

A

Type 1 hypersensitivity reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is type 1 immediate hypersensitivity?

A

Greatly enhanced sensitivity to normally innocuous substances, leading to physiological responses and tissue damage, resulting in the signs and symptoms of allergic reactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is an allergy?

A

IgE-mediated antibody response to external antigen (allergen)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What conditions are caused by allergies?

A
  • Asthma
  • Hayfever
  • Urticaria
  • Angioedema
  • Atopic eczema
  • Food allergy
  • Drug allergy
  • Anaphylaxis
  • Allergic rhinitis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are common allergens?

A
  • Dust mite faeces
  • Animal dander
  • Shellfish
  • Pollen
  • Latex
  • Bee and wasp venom
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are allergens?

A

Many allergens are soluble proteins and function as enzymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Why is the prevalence of allergy increasing?

A

The “Hygiene Hypothesis” - Improved sanitation and decreased incidence of infectious disease results in increased predisposition to allergic conditions during childhood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Why is it beneficial for a child to grow up with older siblings, daycare centre, farming environment, helminth infections, microbial exposure, or pets?

A

Infections or viruses contracted from these factors enhance the maturation of the immune system, resulting in protection against asthma and allergy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the difference in immune response to an antigen between an isolated child in a sterile environment, and a child who has been exposed to many infections wth bacteria and viruses?

A
  • Isolated child - CD4+ cells become activated by antigens, differentiate to form TH2 cells which secrete cytokines that cause B cells to secrete IgE, activating mast cell response
  • Exposed child - CD4+ T cells more likely to differentiate into TH1 cells, response is “dampened down”
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is a TH1 immune response to an antigen?

A

No allergies - cell mediated protective immunity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is a TH2 immune response to an antigen?

A

Allergies - antibody mediated immunity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the general clinical features of type I allergic disease?

A
  • Occurs quickly after exposure to antigen (minutes or 1-2 hours)
  • Responses are stereotyped
  • May be associated with more than one organ system
  • Presentation is influenced by site of contact
  • Threshold for reactions may be influenced by cofactors such as exercise, alcohol and infection
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are specific clinical features of type I allergic disease?

A
  • Asthma
  • Urticaria
  • Angioedema
  • Allergic rhinitis (hay fever)
  • Allergic conjunctivitis
  • Diarrhoea and vominting
  • Anaphylaxis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What cells are involved in allergic disease?

A
  • B lymphocytes - recognise antigen, produce antigen-specific IgE antibody
  • T lymphocytes - TH2 cells provide help for B lymphocytes to make IgE antibody
  • Mast cells, eosinophils and basophils - inflammatory cells that release vasoactive substances (affect diameter of blood vessels)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe the process of an allergic response

A
  • Stimulation of allergen-specific cells by allergen-derived peptides after being presented by dendritic cells via class II MHC molecules
  • Differentiation of CD4+ T cells into effector TH2 cells
  • TH2 cells produce IL-4, IL-13 and IL-15
  • These cytokines stimulate B cells to stop producing IgM antibodies and start producing IgE
  • Also stimulate differentiation and movement of eosinophils from bone marrow to blood
  • Also activate mast cells and eosinophils at sites of allergen exposure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

When is a TH2 response useful?

A

Immune protection against parasitic worms (helminths) - not so good for abnormal reactions to allergens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are mast cells?

A

Tissue-resident cells that produce vasoactive substances (histamine, tryptase, heparin, leukotrienes, prostaglandins, pro inflammatory cytokines like IL-4 and TNF-a)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What vasoactive substances are produced by mast cells?

A
  • Histamine, Tryptase, Heparin
  • Leukotrienes, prostaglandins,
  • Proinflammatory cytokines including IL-4 and TNFalpha
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How do mast cells orchestrate the inflammatory cascade?

A
  • Increase blood blow
  • Contraction of smooth muscle
  • Increase vascular permeability
  • Increase secretions at mucosal surfaces
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the function of mast cells?

A

Important in defence against parasites and in wound healing

25
Q

What is the role of mast cells in the first encounter with an antigen?

A
  • Express receptors for Fc region of IgE antibody on their surface (FcER1 receptors)
  • On first encounter with allergen, B cells produce antigen-specific IgE antibody
  • Allergen is cleared
  • Residual IgE antibodies bind to circulating mast cells via Fc receptors
  • No great consequence
26
Q

What is the role of mast cells once antigen is re-encountered?

A
  • Allergen binds to IgE-coated mast cells and disrupts cell membrane (degranulation)
  • Results in release of vasoactive mediators like tryptase and histamine
  • Also increased cytokine and leukotriene transcription
27
Q

What do release of vasoactive mediators cause?

A

Clinical manifestations like: urticaria, angioedema, asthma, allergic rhinitis, allergic conjunctivitis, anaphylaxis

28
Q

What is extrinsic asthma?

A
  • Response to external allergen

* IgE mediated

29
Q

What is intrinsic asthma?

A
  • “Non-allergic” asthma

* Not IgE mediated

30
Q

What are the clinical effects when an allergic reaction occurs in the lung?

A
  • Muscle spasm - causes bronchoconstriction, wheeze
  • Mucosal inflammation - causes oedema and increases secretions (sputum)
  • Inflammatory cell infiltrate - infiltration of lymphocytes and eosinophils into bronchioles
31
Q

What is urticaria?

A

Has a number of names:

  • Hives
  • Wheals
  • Nettle rash
  • Blisters
32
Q

When do urticaria lesions appear?

A

Lesions appear with an hour and last for 2-6 hours (in some cases, 24 hours)

33
Q

What is nettle rash?

A
  • Surface of nettles covered in fine hairs

* Base of each hair contains histamine, formic acid

34
Q

What is angioedema?

A

Self-limited, localised swelling of subcutaneous tissues or mucous membranes

35
Q

What are clinical features of angioedema?

A
  • Non-pitting oedema
  • Often without clear demarcation (boundary)
  • Generally not itchy unless associated with urticaria
36
Q

What are the clinical features of anaphylaxis?

A
  • Sense of impending doom
  • Low blood pressure
  • Dysphagia - difficulty swallowing
  • Tissue swelling
  • Rash
  • Vomiting
  • Clammy skin
37
Q

What steps are involved in diagnosing allergic disease?

A
  • Confirm diagnosis
  • Identify causative agents - pinpoint specific allergen, target measures to reduce exposure and encourage lifestyle modification
  • Determine risk of future severe reaction
  • Determine appropriateness of therapy
38
Q

What are key features of an allergy history?

A
  • What does the patient mean by allergy?
  • Ask about generic features of IgE mediated reactions
  • What allergens are involved?
  • History of allergy disease?
  • Previous investigations for allergy?
  • Has elimination of trigger made any difference to symptoms?
39
Q

Specific investigations for allergies?

A

Elective investigations

  • Skin prick tests
  • Quantitate specific IgE to allergen
  • Challenge test - supervised exposure to the putative antigen

During acute anaphylactic episode
* Evidence of mast cell degranulation (by measuring serum mast cell tryptase levels)

40
Q

How are IgE mediated allergic disorders managed? (6)

A
  • Avoidance of allergen
  • Drugs that block mast cell activation
  • Drugs that prevent effects of mast cell activation
  • Anti-inflammatory agents
  • Management of anaphylaxis
  • Immunotherapy
41
Q

How can triggers be identified for patients with IgE mediated disorders? (3)

A
  • Clinical history
  • Specific IgE tests
  • Skin prick tests
42
Q

What drugs are used to block mast cell activation?

A

Mast cell stabilisers e.g. sodium cromoglycate

43
Q

What is sodium cromoglycate used for? (2)

A

Mast cell stabiliser (prophylaxis)

  • Stabilises mast cell membranes
  • Prevents release of inflammatory mediators from mast cells e.g. histamine
44
Q

How is sodium cromoglycate administered?

A

Topical spray

45
Q

What conditions can sodium cromoglycate be used for? (3)

A
  • Allergic rhinitis
  • Exercise induced asthma
  • Allergic conjunctivitis
46
Q

What drugs are used to prevent the effects of mast cell activation? (2)

A
  • Anti-histamines

* Leukotriene receptor antagonists

47
Q

What are anti-histamines? What do they do? What are they used for?

A
  • H1 receptor antagonists
  • Block biological effects of histamines
  • Useful prophylactically and to control symptoms
48
Q

What is the mainstay treatment of allergic disease?

A

Anti-histamines

49
Q

What are examples of anti-histamines? (2)

A

Ioratadine and cetirizine

50
Q

What are leukotriene receptor antagonists?

A

Block effects of leukotrienes which are synthesised by mast cells after activation

51
Q

What is an example of a leukotriene receptor antagonist?

A

Montelukast

52
Q

What are examples of anti-inflammatory agents?

A

Corticosteroids

53
Q

What are corticosteroids? What do they do?

A
  • Based on naturally occurring steroids
  • Have anti-inflammatory actions: inhibit formation of many different inflammatory mediators like platelet activating factor, prostaglandins, cytokines
54
Q

What is the treatment for anaphylaxis?

A
  • Self-injectable adrenalin (preloaded adrenaline syringe)
55
Q

How does self-injectable adrenaline treat anaphylaxis?

A

Acts on B2 adrenergic receptors to constrict arterial smooth muscle - increases blood pressure limiting vascular leakage, plated bronchial smooth muscle decreasing airflow obstruction

56
Q

What is immunotherapy?

A

Controlled exposure to increasing amounts of allergen

57
Q

Explain the process of immunotherapy (2)

A
  • Subcutaneous injection of tiny amounts of allergen followed by gradual increase in dose
  • May lead to inhibition of anaphylaxis
58
Q

What are the risks of immunotherapy?

A

Anaphylaxis - must be carried out in very controlled environment

59
Q

What can mast cell degranulation be triggered by? (4)

A
  • Binding of IgE to FcER1 receptors
  • Tissue injury
  • Complement activation
  • Some bacteria independently of IgE

Respiratory: Immunology (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions