Allergy and Anaphylaxis

Question 1

What can hypersensitivity lead to?

Answer 1

Tissue Damage

Question 2

How many types of hypersensitivity are there?

Answer 2

4

Question 3

What is the mediator of a type 1 hypersensitivity reaction?

Answer 3

IgE

Question 4

What is the onset of a type 1 hypersensitivity reaction?

Answer 4

Within 1 hour

Question 5

What is an example of a type 1 hypersensitivity reaction?

Answer 5

Anaphylaxis

Question 6

What is the mediator of a type 2 hypersensitivity reaction?

Answer 6

IgG or IgM cytotoxic

Question 7

What is the onset of a type 2 hypersensitivity reaction?

Answer 7

Hours to days

Question 8

What is an example of a type 2 hypersensitivity reaction?

Answer 8

Haemolytic Anaemia

Question 9

What is the mediator of a type 3 hypersensitivity reaction?

Answer 9

Immune Complex

Question 10

What is the onset of a type 3 hypersensitivity reaction?

Answer 10

1-3 weeks

Question 11

What is an example of a type 3 hypersensitivity reaction?

Answer 11

Serum Sickness SLE

Question 12

What is the mediator of a type 4 hypersensitivity reaction?

Answer 12

T-Cells

Question 13

What is the onset of a type 4 hypersensitivity reaction?

Answer 13

Days to weeks

Question 14

What is an example of a type 4 hypersensitivity reaction?

Answer 14

Rash SJS

Question 15

What is type 1 hypersensitivity?

Answer 15

Immediate or acute hypersensitivity

Question 16

What can cause a type 1 hypersensitivity reaction?

Answer 16

Pollen
Cat Fur
Insect Stings
Peanuts
Eggs

Question 17

What are the 2 stages of a type 1 hypersensitivity reaction?

Answer 17

Sensitisation
Secondary Exposure

Question 18

What happens during the sensitisation stage of a type 1 hypersensitivity reaction?

Answer 18

Antigen Presenting Cell –> CD4 (TH2) –> B Cells (specific IgE antibodies)

Mast cells and basophils.

Question 19

What happens during the secondary exposure phase of a type 1 hypersensitivity reaction?

Answer 19

Allergen binds to Ab and crosslinks on mast cell and basophil surface

Mast cells and basophils release histamine and other inflammatory mediators

This leads to an inflammatory response

Question 20

What local or systemic effects do secondary exposures to type 1 hypersensitivity have?

Answer 20

Anaphylaxis or anaphylactic shock - epinephrine

Question 21

Where is histamine produced?

Answer 21

Mast Cells
Basophils
Enterochromaffin-like Cells
Neurons

Question 22

Where is histamine found?

Answer 22

Lungs
Skin
GI Tract

Question 23

How does histamine work?

Answer 23

Acts on G Protein Coupled Histamine Receptors

Question 24

What are the 4 subtypes of histamine receptors and where are they found?

Answer 24

H1: CNS, endothelium and smooth muscle H2: CNS, cardiac muscle and stomach H3: CNS (presynaptic), myenteric plexus H4: basophils, eosinophils and mast cells

Question 25

What is the physiological effect of histamine on the immune system?

Answer 25

Releases neutrophils from bone marrow (H4) Mast Cell Chemotaxis (H4) Role in hypersensitivity type 1 reactions (H1)

Question 26

What are the physiological effects of histamine on the cardiovascular system?

Answer 26

Vasodilaton (H1) Increased cardiac output (H2) Oedema - increased permeability of post-capillary venules (H1)

Question 27

What are the physiological effects of histamine on smooth muscle?

Answer 27

Constriction (H1) - ileum, bronchim bronchioles, uterus

Question 28

What are the physiological effects of histamine in the gut?

Answer 28

Stimulates the secretion of gastric acid, intestinal secretions and increases motility (H2)

Question 29

What are the physiological effects of histamine on the CNS and PNS?

Answer 29

H2 and H3 are inhibitory (presynaptic) H1 are excitatory - role in pain and emetic response. Stimulation of sensory nerve endings in the skin results in itching and spread of vasodilation

Question 30

Signs and Symptoms of Anaphylaxis

Answer 30

Swelling of the conjunctiva Runny Nose Swelling of lips, tongue and/or throat Fast or slow heart rate Low blood pressure Hives Itchiness Flushing Lightheadedness Losss of consciousness confusion headache anxiety shortness of breath wheezes or stridor hoarseness pain with swallowing cough cramps abdominal pain diarrhoea vomiting loss of bladder control

Question 31

What is a type 2 hypersensitivity reaction?

Answer 31

Antibody dependent cytotoxic hypersensitivity

Question 32

What are some examples of oral sedating antihistamines?

Answer 32

Chloramphenamine Clementine Ketotifen

Question 33

What are some examples of oral non-sedating antihistamines?

Answer 33

Acrivastine Bilastine Cetirizine Desloratadine Fexofenadine Levocetirizine Loratadine Mizolastine Rupatidine