Type II, III, IV Hypersensitivity Reaction

Question 1

What caused Type II hypersensitivity reactions?

Answer 1

Cytoxocity via:
1. IgG and IgM Ab directed against autoAg on cells or chemicals on host cell surface proteins
2. Genetic susceptibility to autoimmunity or drug reactivity

Question 2

How can IgG and IgM cause hostcell damage?

Answer 2

Opsonization
Complement
Ab (IgG) dependent cytotoxicity by Killer cells
Autoantibody leading to receptor blockade/removal

Question 3

Examples of Hypersensitivity Type II diseases

Answer 3

Ab mediated cellular dysfunction
Autoimmune hyperthyroidism
Myasthenia Gravis
Immune mediated thrombocytopaenia
IMHA

Question 4

What causes a Type III Hypersensitivity Reaction?

Answer 4

Aollume Ag/Ab Immune complexes that
1. Form locally in tissues
2. Form in blood and get deposited in walls/underlying tissue - vasculitis

Question 5

What factors influence the potential for a type III response?

Answer 5

Haemodynamics
Ab/Ag parameters:
-Ag/Ab ratio
-weak Ab response
-low affinity ab
-Ag/Ab persistence

Question 6

What are the steps that cause the pathogenesis of Systemic Immune Complex (Type III) Disease

Answer 6

1. Formation of Ag/Ab complex in circulation
2. Ag/Ab complex deposition
3. Activation of Phagocytes and mast cells through FcReceptors
4. Complement cascade activation
5. Release of chemotactic factors, inflammatory mediators, lysosymal enzymes, proteases
6. Epithelial damage, vasculitis

Question 7

What are some examples of disease caused by Type III Hypersensitivity?

Answer 7

Glomeulonephritis
Arthritis
Carditis
Cutaneous vasculitis

Question 8

What are three causes of Type III hypersensitivity reactions?

Answer 8

Self
Extrinsic
Persistent Infection

Question 9

What antigen is involved in persistent infection caused immune complex disease and where do the complexes deposit?

Answer 9

Microbial/viral
Infected organ, kidney

Question 10

What antigen is involved in autoimmune caused immune complex disease and where do the complexes deposit?

Answer 10

Self
Kidneys
Joints
Ateries
Skin

Question 11

What antigen is involved in extrinsic caused immune complex disease and where do the complexes deposit?

Answer 11

Environmental (moulds, plants, animals), serum sickness, drugs, etc
Lungs
Kidney

Question 12

What are some examples of Type III Hypersensitivity reactions?

Answer 12

Serum sickness
Chronic Obstructive Pulmonary Disease - horses
Arthus reaction

Question 13

What is an arthus reaction?

Answer 13

Formation of an Ag/Ab complex after intradermal ag injection (ie. vx)
With previous sensitization - Arthus reaction

Question 14

What causes a Type IV Hypersensitivity Reaction?

Answer 14

Ag injected into skin of sensitized ind inducing a slow inflammatory response
Delayed type hypersensitivity reaction
Mediated by T cells and Macrophages

Question 15

What are some types of hypersensitivity and their reaction times?

Answer 15

Tuberculin - 48 hr
Jones Mote (Cutaneous basophil hypersens) - 24 hr
Contact sensitivity - 48 hr
Granulomatous - >14 days

Question 16

What is a contact allergen and what are some examples?

Answer 16

Highly reactive molecule that reacts with self-protein -> haptenated antigen
Poison Ivy - Urushiol Oil
Nickel

Question 17

Describe granulomatous inflammation in Type IV Hypersensitivity reactions

Answer 17

Tight collection of mac and t cells
Mac differentiate -> epitheloid and giant cells
Granulomas cause distortion and inflammation of normal tissue