Hypersensitivity reactions

Question 1

What is Type I hypersensitivity?

Answer 1

Immediate hypersensitivity - localised or systemic allergic reaction

Question 2

What mediates Type I hypersensitivity?

Answer 2

IgE binding to Basophils and Mast cells

Question 3

Examples of Type I hypersensitivity?

Answer 3

Asthma
Anaphylaxis
Hay fever

Question 4

What is Type II hypersensitivity?

Answer 4

Direct cell killing, tissue specific

Question 5

What mediates Type II hypersensitivity?

Answer 5

Complement activation by IgG or IgM

Question 6

Examples of Type II hypersensitivity?

Answer 6

ABO incompatibility

Question 7

What is Type III hypersensitivity?

Answer 7

Immune complex reacton

Question 8

Mechanism of Type III hypersensitivity?

Answer 8

Immune complexes are deposited in the tissues, where they activate the complement system, causing generalised inflammation

Question 9

Examples of Type III hypersensitivity?

Answer 9

Lupus
Extrinsic Allergic Alveolitis
Rheumatoid Arthritis

Question 10

What is Type IV hypersensitivity?

Answer 10

T-cell mediated delayed hypersensitivity

Question 11

Mechanism of Type IV hypersensitivity?

Answer 11

T cells over-stimulation by antigen causes cytokine production, leading to inflammation and tissue damage.

Question 12

Examples of Type IV hypersensitivity?

Answer 12

contact dermatitis
TB
Graft-vs-host disease
Type 1 diabetes