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R - Immunology (Rach and Meg) > Type 1 Hypersensitivity > Flashcards

Type 1 Hypersensitivity Flashcards

1
Q

What is a hypersensitivity reaction?

A

An exaggerated immune response against an antigen that can cause damage

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2
Q

What is autoimmunity?

A

When the hypersensitivity reaction is against a self antigen

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3
Q

What is a hapten?

A

A small molecule that can bind to a protein and stimulates antibody production.

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4
Q

What is an example of a hapten?

A

Penicillin.

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5
Q

What is a cytokine storm?

A

When the immune response causes damage and this damage is greater than the benefit. They recruit pro inflammatory cells and can cause a systemic response.

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6
Q

What is type 1 hypersensitivity also known as?

A

Allergy

Atopy

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7
Q

What is a type 1 hypersensitivity reaction?

A

An immediate hypersensitivity to environmental antigens.

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8
Q

What type of antigens cause type 1 hypersensitivity reaction?

A 
Environmental antigens only.
Food 
mould
drugs
medications
pollen
bee stings
latex
lotions
soaps
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9
Q

Which antibody is most common in type 1 hypersensitivity reaction?

A

IgE

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10
Q

What is the pathophysiology behind type 1 hypersensitivity reactions?

A
  • Antigen enters the Body
  • Th2 (T helper cells 2) secrete IL4 (a cytokine)
  • This causes B cells to produce IgE antibodies and turns off Th1 cells
  • Mast cells attach themselves to IgE antibodies and eosinophils also migrate towards the hypersensitivity reaction
  • Mast cells and eosinophil cells degranulate and release histamine, prostaglandins and leukotrienes
  • This causes an immune response - smooth muscle contraction, blood vessel dilation, oedema, hives
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11
Q

What is the difference between Th1 and Th2?

A

Th1 - gives an immune response against intracellular parasites
Th2- gives an immune response against extracellular parasites

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12
Q

How are type 1 hypersensitivity reactions mediated?

A

Through the degranulation of mast cells and eosinophils

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13
Q

How long do type 1 hypersensitivity reactions take to feel effects?

A

Within seconds - its immediate

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14
Q

What are allergens?

A

External antigens which cause an allergic reaction

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15
Q

what is someone specifically allergic to in a penicillin allergy?

A

Beta lactam

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16
Q

Which exposure to an allergen is most serious?

A

The second - after IgE antibodies have been created.

17
Q

When do late phase allergic reactions occur?

A

8-12hrs after exposure

18
Q

What is the role of cytokines?

A

They excite T cells (Th2) which in turn excite B cells to produce IgE antibodies specific to the antigen

19
Q

What are known genetic predispositions for type 1 hypersensitivity reactions?

A

Change in filaggrin

Increased Th2

20
Q

When does an immediate allergic response occur?

A

The 2nd encounter to the antigen, once IgE antibodies have been produced

21
Q

What happens during anaphylaxis?

A 
Airways constrict
Increased vascular permeability
Low blood pressure 
Angioedema
Shift of fluid from intravascular to extravascular space
22
Q

What are common types of type 1 hypersensitivity reaction?

A 
Anaphylaxis
Asthma
Rhinitis
Urticaria 
Angioedema
Atopic eczema 
Dermatitis
Hives
23
Q

What is an allergic march?

A

When you develop an allergy young you’re more likely to develop more as you age.

24
Q

What is the pathophysiology behind allergic rhinitis?

A

Mast cells degranulate and cause nasal stuffiness and sneezing
Leukotrines increase mucus section = runny nose

25
Q

What is the pathophysiology behind asthma?

A

Leukotrines cause smooth muscle contraction

26
Q

What are the treatments for type 1 hypersensitivity reactions?

A 
Desensitisation 
Beta 2 adrenergic agonists 
Epinephrine
Antihistamines
Montelukast
27
Q

What do beta 2 adrenergic agonists do?

A

Example - salbutamol

prevent smooth muscle contraction in the chest

28
Q

What does epinephrine do?

A

Its life saving in anaphylaxis
Stimulates alpha and beta adrenergic receptors which decrease vascular permeability, increase blood pressure and reverse airway obstruction

29
Q

What do antihistamines do?

A

Block histamine receptors
Good for skin, nose and mucus allergens

Doesn’t work in asthma (not caused by histamine release)

30
Q

How does montelukast work>

A

Its a specific receptor antagonist that blocks the effect of leukotrienes

31
Q

Which 3 things are released by mast cell degranulation?

A

Histamine
Leukotrienes
Prostaglandins

32
Q

How do corticosteroids work?

A

Prevent the hypersensitivity reaction.

R - Immunology (Rach and Meg) (11 decks)

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