Allergy and hypersensitivity

Question 1

what is a type 1 hypersensitivity reaction?

Answer 1

Type I hypersensitivity is an immediate reaction to environmental antigens mediated via IgE

Question 2

what is atophy?

Answer 2

Atopy is an inherited trait for Type I hypersensitivity

Question 3

what are allergens?

Answer 3

Allergens are antigens that trigger allergic reactions

Question 4

what effect does histamine have?

Answer 4

Vasodilatation, increased capillary permeability, chemokinesis, bronchoconstriction

Question 5

what effect does neutral proteases ( try-gases, chemises and carboxypeptidase A) have?

Answer 5

Increased vascular permeability, airway hyperresponsiveness, cell recruitment

Question 6

what effect does proteoglycan have?

Answer 6

Binds granule proteases

Question 7

what effect does neutral proteases such as b-glucosaminidase have?

Answer 7

Activates C3
Splits off glucosamine

Question 8

what are the main areas exposed to antigens?

Answer 8

skin, gi tract and lungs

Question 9

what effect do Eosinophil chemotactic factors and Neutrophil chemotactic factors have?

Answer 9

eosinophil chemotaxis
neutrophil chemotaxis

Question 10

what effect do platelet activating factor have?

Answer 10

mediator release

Question 11

what effect does IL – 3, 4, 5 & 6 GM-CSF, TNF have?

Answer 11

Macrophage activation, trigger acute phase proteins etc

Question 12

what newly synthesised product does the lipoxygenase pathway include?

Answer 12

Leukotrienes C4, D4, B4

Question 13

what is the effect of the lipoxygenase pathway?

Answer 13

Vasoactive, bronchoconstriction, chemotaxis

Question 14

what is the newly synthesised product in the cycle-oxygenase pathway?

Answer 14

Prostaglandins Thromboxanes

Question 15

what effect does the cyclo-oxygenase pathway have?

Answer 15

Affect bronchial muscle, platelet aggregation and vasodilatation

Question 16

clinical manifestations of allergy

Answer 16

trouble breathing
itching
sneezing
runny nose
headache
red or watery eyes
hives or rash

Question 17

What are the conditions that elicit a type I hypersensitivity reaction?

Answer 17

 Allergen characteristics
 Host factors
 Environmental influences

Question 18

What makes certain proteins allergenic?

Answer 18

 Allergens have the ability to induce a strong IgE response
 Protease activity – Der p 1
 Surface features of protein – Ves v 5
 Glycosylation pattern of protein – Ara h 1

Question 19

The clinical manifestations

Answer 19

 Allergic rhinitis
 Allergic conjunctivitis  Atopic dermatitis
 Urticaria/angioedema  Asthma
 Food allergy
 Drug allergy
 Venom allergy
 Anaphylaxis

Question 20

Treatment options

Answer 20

 Anaphylaxis is a medical emergency  Treatment consists of:
 Adrenaline / epinephrine
 Antihistamines
 Corticosteroids
 Fluid resuscitation
 Bronchodilation
 Other treatment options include:  Allergen avoidance
 Topical corticosteroids
 Antihistamines

Question 21

what is Desensitisation or allergen-specific immunotherapy?

Answer 21

A process whereby the immune system is exposed to gradually increasing doses of allergen in order to develop tolerance

Question 22

how is Desensitisation or allergen-specific immunotherapy administered?

Answer 22

via subcutaneous or sublingual route

Question 23

when is Desensitisation or allergen-specific immunotherapy used?

Answer 23

Used in allergic rhinitis, venom allergy and drug allergies predominantly

Question 24

describe asthma

Answer 24

Partially a type I hypersensitivity phenomenon but also has type IV (cell mediated) and type V (tissue driven) mechanisms

 Large proportion of asthmatics have T2-hi inflammation
 Numerous monoclonal antibodies available