Type 3 Hypersensitivity

Question 1

Type 3

Answer 1

Immune Complex Hypersensitivity
* Formation of immune complex between antigen and antibody
* Subsequent tissue deposition of these
Leads to activation of complement system (chemotactic for neutrophils)

Question 2

What doe neutrophils do in this type of hypersensitivity?

Answer 2

Cytokines draw neutrophils to site of allergen
Neutrophils are unable to ingest complexes embedded in blood vessel walls
* Release toxic granule contents into tissue causing severe tissue damage

Question 3

Subtypes of Type 3

Answer 3

Antibody Excess
Antigen Excess

Question 4

Antibody Excess

Answer 4

High amounts of IgG forming in body
*Antigenic re-exposure is rapidly picked up
*Leads to localised inflammatory system being activated

Question 5

Antigen Excess

Answer 5

Less IgG but lots of antigens
Smaller complexes
Circulate within blood stream and deposit in walls of capillaries
Localised vascular inflammation - vasculitis
□ Thrombosis
□ Necrosis

Question 6

Equine Recurrent Airway Obstruction (RAO)

Answer 6

Sensitisation to mould within hay or dust
Initiates localised inflammatory reaction on inhalation

Question 7

Clinical signs of RAO

Answer 7

○ Flared nostrils
○ Tachypnoea
○ Cough
○ Heave line
○ Wheezing/coughing during exercise
○ Hypertrophy of abdomen

Question 8

Canine Blue Eye

Answer 8

Associated with canine adenovirus
Excess antibody from infection or vaccination
* Immune complexes form within the uveal tract
○ Leads to localised inflammation and oedema within cornea of eye