Hypersensitivity

Question 1

What are hypersensitivity reactions?

Answer 1

A group of disorders in which normally beneficial components of the immune system act in an exaggerated or inappropriate fashion to environmental antigens that do not normally cause tissue damage

Question 2

How do type 1 hypersensitivity reactions arise?

Answer 2

Inappropriate synthesis of IgE

Question 3

What factors can cause allergic reactions?

Answer 3

Genetic
Environmental
Hormonal and neurological
Immune regulatory

Question 4

What is an atopy?

Answer 4

Sub-clinical immune sensitisation caused by IgE

Question 5

What do type 1 hypersensitivity reactions cause?

Answer 5

Mucosal oedema
Capillary leakage
Secretions
Smooth muscle contraction
Vasodilation

Question 6

What are type 2 hypersensitivity reactions?

Answer 6

Mediated by IgG or IgM directed against antigens found on the surface of cells or find within certain tissues

Question 7

How does tissue damage arise via type 2 hypersensitivity?

Answer 7

Complement activation
Fc binding of immunoglobulin and stimulation of phagocytes
Antibody dependent cellular cytotoxicity
Effects on target cell function

Question 8

How do type 3 hypersensitivity reactions arise?

Answer 8

Abnormal deposition of antigen/antibody complexes in tissue

Question 9

What are the types of pathological type 3 reaction?

Answer 9

Serum sickness- immune complexes deposited throughout body tissues
Arthus reaction- complexes form locally in tissues

Question 10

What is type 4 hypersensitivity mediated by?

Answer 10

Th1 cells and the cytokine products

Question 11

How do type 4 hypersensitivity responses occur?

Answer 11

Either structure of the agent of evolved ability of the organism to evade, cofound or counteract the immune system

Question 12

What happens in environmental agents of a low weight?

Answer 12

Bind to host proteins to produce an antigenic stimulus of sufficient size

Question 13

What is the delay between exposure and clinical effect?

Answer 13

48-72 hours

Question 14

What are autoimmune disorders?

Answer 14

Clinical disorders characterised by tissue or organ damage mediated through aberrant cellular and/or humeral immunological mechanisms directed against autoantigens

Question 15

How is immune tolerance produced?

Answer 15

Deletion of auto reactive T cells during cell maturation or inhibiting the activity of autoreactive cells that escape central tolerance

Question 16

What factors cause autoimmune disease?

Answer 16

Genetic
Immune regulatory factors
Hormonal factors
Environmental factors
Other

Question 17

What effector mechanisms are involved in autoimmune disease?

Answer 17

B and T cell activity
Antibody activation of complement mediated inflammation
Immune complex formation
Recruitment of innate immune components