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MPharm 2 - PH2113 COPY > Unit 3 - Hypersensitivity Rections > Flashcards

Unit 3 - Hypersensitivity Rections Flashcards

1
Q

What is hypersensitivity damage mediated by?

A

The same attack mechanisms that mediate normal immune responses to pathogens
- adaptive immune system

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2
Q

What is hypersensitivity?

A

An exaggerated response of the immune system to ‘foreign’ antigen resulting in tissue damage

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3
Q

What is needed to produce a hypersensitivity reaction?

A

A sensitisation step is needed as a hypersensitivity reaction cannot manifest upon first exposure

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4
Q

What is another term for hypersensitivity?

A

Allergy

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5
Q

What is an antigen?

A

A protein or small molecule which is capable of complexing with protein (hapten)

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6
Q

What is sensitisation?

A

Antigen contact, typically low-dose via mucous membrane (respiratory, GI tract)
- primary IgE production

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7
Q

What process happens on re-exposure to an antigen?

A

Pre-formed IgE (allergen-specific) triggers mast cell activitation
Immediate release of mediator (mast cell degranulation) and then early and late phase synthesis of other inflammatory mediators

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8
Q

How long does a hypersensitivity reaction take?

A

Can occur within seconds - minutes of exposure

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9
Q

Give some examples of hypersensitivity reactions

A 
Allergic asthma
Allergic rhinitis (hay fever)
Anaphylaxis
Food allergy
Hives
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10
Q

What are the symptoms of allergic asthma?

A

Narrowing of airways

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11
Q

What are the symptoms of allergic rhinitis?

A 
Itchy eyes
Conjunctivitis
Sore throat
Ear pain
Hearing loss
Itchy ears
Snoring
Mouth breathing
Headache
Congestion
Sneezing
Rhinorrhea
Congestion
Nasal drip
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12
Q

What are the symptoms of a food allergy?

A 
Eczema
Itchy mouth
Swelling face
Swelling tongue
Swelling lips
Nausea or vomiting
Abdominal pain
Trouble breathing
Dizziness
Diarrhoea
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13
Q

What are the symptoms of anaphylaxis?

A

Normal allergy symptoms as well as:

  • swelling of the throat and mouth
  • difficulty breathing
  • lightheadedness
  • confusion
  • blue skin or lips
  • collapsing and losing consciousness
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14
Q

What is the function of mast cells?

A
  • exert critical proinflammatory functions
  • potential immunoregulatory roles in various immune disorders
Mast cell release of mediators such as:
histamine, 
leukotrienes, 
Cytokines,
chemokines,
neutral proteases (chymase and tryptase).

Early phase reactants (minutes)
Activates eosinophils

Late phase reactants (hours)
Il-4, Il-5, Il-10
Leukotrienes, LTB4, LTC4, 
cause smooth muscle contraction 
 attract more immune cells like eosinophils, mast cells, neutrophils
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15
Q

Give examples of mediators released by mast cells

A
  • histamine
  • leukotrienes
  • cytokines
  • chemokines
  • neutral proteases (chymase and tryptase)
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16
Q

What is the effect of the release of interleukin 5 in a hypersensitivity reaction?

A

Activates eosinophils

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17
Q

What is the effect of the release of IL-4, IL-5, IL-10, leukotrienes, LTB4 and LTC4?

A
  • smooth muscle contraction

- attract more immune cells e.g. eosinophils, mast cells, neutrophils

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18
Q

Which receptor binds histamine?

A

H1 receptors

19
Q

What is the effect of histamine binding to H1 receptor during a hypersensitivity reaction?

A

Causes smooth muscles around bronchi to contract -> airways get smaller -> DIFFICULTY BREATHING
Causes blood vessel dilation -> increases blood flow -> DECREASES BLOOD PRESSURE
Increased permeability of the blood vessel wall -> leaking into the intercellular space -> OEDEMA (swelling) or URTICARIA (hives)

20
Q

Give four examples of generic allergic symptoms

A
  • hives (urticaria)
  • eczema
  • allergic rhinitis
  • allergic asthma
21
Q

How can an allergic reaction be assessed?

A
  • symptoms
  • history of allergy
  • exposure to allergens
  • previous episodes
  • family or personal history of asthma, eczema or atopy
  • current/previous treatment
  • consider other diagnosis including pneumonia
22
Q

What is Atopy?

A

A greater tendency in the clinical presentation of Type I hypersensitivity occurring in subjects with a family history of one or other similar conditions

  • hay fever
  • asthma
  • eczema
  • urticaria
23
Q

How might an atopic individual react, despite not suffering from any common allergies?

A

Immediate wheal-flare skin reactions to intradermal injection of common environmental allergens

24
Q

What does a raised level of serum IgE indicate?

A

A diagnosis of an atopic individual, although a normal IgE serum level does not exclude atopy

25
Q

What is the relationship between Human Leukocyte Antigen (HLA) and specific antigens?

A

90% of all responders to a low MW (5 kDa) allergen from Ragweed are HLA-DR2

26
Q

What is there a higher frequency of in the general ‘allergic’ population?

A

HLA-B8

27
Q

Give examples of environmental pollutants which may increase mucosal permeability to allergens

A
  • sulphur dioxide

- diesel exhaust

28
Q

What observation led to the Hygiene Hypothesis?

A

Observation that children in families with older siblings were less likely to develop allergies due to increased incidence of infection in early children, transmitted from older siblings

29
Q

What was the idea behind the Hygiene Hypothesis?

A

Exposure to infectious agents may decrease the risk of allergy was first introduced in 1989

30
Q

What is the Hygiene Hypothesis?

A

Increased exposure to microorganisms correlates with a decreased tendency to develop allergy

31
Q

How should allergic reactions be treated?

A 
Avoid exposure to allergens
Allergy medicines
- antihistamines
Decongestants
Lotions and creams
Corticosteroids
Adrenaline (severe reactions)
Immunotherapy (desensitisation)
32
Q

Give examples of mast cell stabilisers that can be used to treat hypersensitivity reactions

A

Chromoglycate

Nedocromil

33
Q

Give examples of leukotriene receptor antagonists that can be used to treat hypersensitivity reactions

A

Singulair

Accolate

34
Q

How do immunosuppressant antibodies work to treat hypersensitivity reactions?

A

Interfere with IL-5 pathway eosinophil chemoattractant

35
Q

How do mast cell stabilisers work to reduce hypersensitivity reactions?

A

They block mast cell degranulation, stabilising the cell and thereby preventing the release of histamine and related mediators

  • one suspected pharmacodynamic mechanism is the blocking of IgE-regulated calcium channels
  • without intracellular calcium, the histamine vesicles cannot fuse to the cell membrane and degranulate
36
Q

What are leukotriene receptor antagonists also known as?

A

Antileukotriene

37
Q

What is the function of leukotriene receptor antagonists?

A

Opposes the function of inflammatory mediators

  • leukotriene-related enzyme inhibitor (arachidonate 5-lipoxygenase)
  • leukotriene receptor antagonist (cysteinyl leukotriene receptors)
38
Q

What are leukotriene receptor antagonists effective for treating?

A

Less effective than corticosteroids for treating asthma but more effective for treating certain mast cell disorders

39
Q

What are antihistamines used to treat?

A

Allergic rhinitis and other allergies

40
Q

What are the two types of antihistamines?

A
  • H1-antihistamines

- H2-antihistamines

41
Q

How do H1 antihistamines work?

A

Binding histamine H1 receptor in mast cells, smooth muscle and endothelium

  • to treat allergic reactions in the nose
  • itching
  • runny nose
  • sneezing
  • to treat insomnia, motion sickness or vertigo caused by problems in the inner ear
42
Q

How do H2 antihistamines work?

A

Binding histamine H2 receptors in upper gastrointestinal tract, primarily in the stomach

  • to treat gastric acid conditions
  • peptic ulcers
  • acid reflux
43
Q

What is Benadryl?

A

Brand name for different H1 antagonist antihistamine preparations

  • acrivastine - Benadryl allergy relief
  • cetirizine - Benadyl One a Day relief

MPharm 2 - PH2113 COPY (39 decks)

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