Type III Hypersensitivity

Question 1

1. Type III Hypersensitivity is also known as ___________ hypersensitivity.

Answer 1

Immune complex disease

Question 2

2. Type III hypersensitivity is more common in __________ diseases

Answer 2

Viral

Question 3

What are the important features for formation of immune complexes?

Answer 3

Small numbers of immune complexes (soluble or insoluble) are always forming due to the binding of antibodies, antigen, and complement

Question 4

In a normal immune complex, how are insoluble complexes removed?

Answer 4

They are removed by a mononuclear phagocyte system- monocytes, macrophages, tissue specific macrophages (Kupffer cells)

Question 5

In a normal immune complex, how are soluble complexes removed?

Answer 5

They are removed by binding to complement receptors on erythrocytes (primates) or platelets (most other species). These complexes then bind to phagocytes, where the complex is stripped off and leaves the platelet or erythrocyte free for circulation

Question 6

In immune complex disease, what does antibody excess cause?

Answer 6

Local disease, where complement is activated by antibody-antigen complex, which then recruits and activates neutrophils

Question 7

What are examples of Antibody diseases and what are clinical signs of each?

Answer 7

1. Blue eye- corneal edema/ opacity
2. Hypersensitivity pneumonitis- acute alveolitis, vasculitis, fluid exudation, and occasionally chronic bronchiolitis
3. Staphylococcal hypersensitivity- pruritic pustular dermatitis (puppy strangles)

Question 8

How does canine adenovirus-1 infection cause a Type III reaction?

Answer 8

It is an immune complex lesion with deposition in the anterior uvea resulting in blue eye

Question 9

How do moldy hay spores cause a Type III reaction?

Answer 9

These spores reach alveoli and induce chronic antigenic sensitization. The antibodies then complex with antigen resulting in hypersensitivity pneumonitis

Question 10

In immune complex disease, what does antigen excess cause?

Answer 10

Generalized disease, where the immune complex formation is located within the blood

Question 11

How does a generalized Type III infection occur?

Answer 11

1. High levels of antigen present
2. Increase antibodies= increased numbers of immune complexes
3. Complexes form within blood and then bind to vessels or other circulating cells
4. Once bound, complexes induce neutrophil accumulation and endothelial proliferation

Question 12

What are the most common generalized effects of immune complex disease?

Answer 12

1. Glomerulonephritis
2. Vasculitis
3. Arthritis
4. Anemia
5. Leukopenia
6. Thrombocytopenia

Question 13

What organs are commonly affected by generalized Type III infection?

Answer 13

Kidney (glomerulus)
Vasculature
Synovium (joints)

Question 14

14. What are some infectious diseases associated with clinical MPGN?

Answer 14

1. Chronic viral- Equine Infectious Anemia Virus, Infectious Canine Hepatitis, Aleutian Disease, African Swine Fever
2. Chronic parasitic- Leishmaniasis
3. Chronic bacterial- Lyme disease, Ehrlichiosis, and Anaplasmosis

Question 15

Which will be lost first in MPGN, albumin or globulin?

Answer 15

Albumin will be lost first due to its size, in later stages both will be lost