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DEN 2027 - Disease Mechanisms > Hypersensitivity > Flashcards

Hypersensitivity Flashcards

1
Q

What is hypersensitivity?

A

Exaggerated or inappropriate immune response

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2
Q

What 3 things can hypersensitivity lead to?

A
  1. Tissue damage
  2. Serious disease
  3. Death
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3
Q

Give an example of hypersensitivity reactions

A

Anaphylaxis

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4
Q

What is angioedema in anaphylaxis?

A

A person is unable to breathe so oxygen has to be provided by a tube

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5
Q

Name 4 types of hypersensitivity reactions?

A
  1. Type I - IgE mediated
  2. Type II - Cytolytic or cytotoxic
  3. Type III - Immune complex
  4. Type IV - Cell mediated immunity
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6
Q

What are 2 main differences between type 1, type 2 and type 3 hypersensitivity reactions and type 4 hypersensitivity reactions?

A
  1. Type 1, type 2 and type 3 hypersensitivity reactions are mediated by antibodies and type 4 hypersensitivity reactions are mediated by T-cells
  2. Type 1, type 2 and type 3 hypersensitivity reactions are immediate and type 4 hypersensitivity reactions are delayed
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7
Q

What are the 3 phases of Type I Hypersensitivity?

A
  1. Sensitisation
  2. Activation
  3. Effector
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8
Q

What occurs during the sensitisation phase of Type I Hypersensitivity?

A
  • Exposure to allergen activated Th2 cells which stimulate B cells to form IgE producing plasma cells
  • IgE produced binds to Fc receptors on mast cells and basophils
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9
Q

What occurs during the activation phase of Type I Hypersensitivity?

A

Re-exposure to antigen triggers mast cells and basophils to response by release of granules

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10
Q

What occurs during the effector phase of Type I Hypersensitivity?

A

Complex response occurs as a result of histamine and other active agents released by mast cells and basophils

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11
Q

What are 5 effects of the effector phase on the body during Type I Hypersensitivity?

A
  1. Contraction of bronchial smooth muscles
  2. Increase mucus secretion
  3. Increased permeability of venules due to contraction of endothelial cells
  4. Vasodilation
  5. Stimulation of nerve endings
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12
Q

Name 3 physical expressions of effectors during Type I Hypersensitivity

A
  1. Airways obstructed
  2. Drop in blood pressure
  3. Cough
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13
Q

How quickly does Type I Hypersensitivity occur from exposure?

A

Immediate

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14
Q

Name 4 examples of localised Type I Hypersensitivity

A
  1. Hay fever (allergic rhinitis)
  2. Food allergy
  3. Atopic dermatitis
  4. Asthma
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15
Q

What is systemic anaphylaxis?

A

Shock-like and often fatal state initiated by an allergen introduced into the blood or absorbed by the gut or skin

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16
Q

Name 4 things which can cause systemic anaphylaxis

A
  1. Nuts
  2. Insulin
  3. Seafood
  4. Venom from bees, wasps or ants
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17
Q

What is the treatment for systemic anaphylaxis?

A

Epinephrine

18
Q

What are the 3 main types of treatment available for Type I Hypersensitivity reactions?

A
  1. Environmental
  2. Pharmacologic
  3. Immunological
19
Q

Name 5 pharmacologic treatments for Type I Hypersensitivity reactions

A
  1. Antihistamines
  2. Cromolyn chloride
  3. Corticosteroids
  4. Theophylline
  5. Epinephrine
20
Q

Name 2 immunological treatments for Type I Hypersensitivity reactions

A
  1. Desensitization

2. Humanized anti-IgE antibodies

21
Q

How does Type II Hypersensitivity work?

A

Antibody bound to cell surface antigen activates complement system or mediates cell destruction by antibody-dependent cell mediated cytotoxicity (ADCC)

22
Q

What two antibodies can mediate Type II Hypersensitivity?

A
  1. IgG

2. IgM

23
Q

What is the main example of Type II Hypersensitivity?

A

Blood transfusion reactions

24
Q

How does Th2 cells cause B cells to divide?

A

It produces IL-4 which causes the B cells to become plasma cells by class switching

25
What 3 reactions can be caused if incorrect blood transfusion?
1. Intravascular haemolysis 2. Increased hemoglobulin filtered through in kidneys 3. Hemoglobulin converted to toxic bilirubin
26
What are 5 physical symptoms of an incorrect blood transfusion?
1. Fever 2. Chills 3. Nausea 4. Lower back pain 5. Blood clotting
27
Name 3 common sites of Type III Hypersensitivity reactions?
1. Blood vessel walls 2. Synovial membrane in joints 3. Glomerular basement membrane of kidney
28
What occurs during the deposition of complexes?
Recruitment of neutrophils to the site, where lytic enzymes from granular release causes tissue damage
29
What facilitates the movement of neutrophils to site of complexes?
Compliment proteins produced by the complexes
30
Why are lytic enzymes released as opposed to phagocytosis occuring?
Neutrophils are hyper activated as they cannot take up larger immune complexes
31
Name 3 types of Type III Hypersensitivity reactions
1. Farmers lung 2. Pigeons fancier's disease 3. Serum sickness
32
What is a Type IV Hypersensitivity reaction?
Localized inflammatory response induced by Th cells
33
What characterises a Type IV Hypersensitivity reaction?
A large influx of inflammatory cells and macrophages
34
Why are Type IV Hypersensitivity reactions important?
Important in defence against parasites and bacteria which live within cells
35
Give 5 examples of pathogens associated with Type IV Hypersensitivity
1. Mycobacterium tuberculosis 2. Mycobacterium leprae 3. Candida albicans 4. Herpes simplex 5. Measles
36
What are Langerhans cells?
Immune cells found in the spleen
37
What occurs during Type IV Hypersensitivity reactions?
- Antigen presenting cells activate Th1 cells - Th1 cells cause release of cytokines and chemokines which attract macrophages - Activated macrophage increase MCH class II expression to amplify Th1 response
38
What are 4 effects of macrophage effect during Type IV Hypersensitivity?
1. MHC class II expression increased 2. TNF receptors increased 3. Oxygen radicals increased 4. Nitric oxide increased
39
What can occur if there is a prolonged DTH response?
Formation of granulomas due to continuous activation of macrophages
40
Name the 5 steps during the continuous activation of macrophages to cause tissue damage
1. Macrophages are hyper activated so adhere to each other 2. Fuse to form granulomas 3. Form palpable nodules 4. Release lytic enzymes 5. Tissue damage
41
What is an example of prolonged DHT response?
Mycobacterium tuberculosis in the lung
42
Describe the stages of contact dermatitis
- Antigen in poison ivy oil penetrates skin - Forms covalent bonds with proteins - Proteins taken up by Langerhans cells and macrophages - Antigenic peptides presented via MHC class II to Th1 cells - Th1 induces immune response - Recruitment of activated macrophages to site of inflammation and release of lytic enzymes

DEN 2027 - Disease Mechanisms (20 decks)

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