Hypersensitivity and Autoimmunity

Question 1

What physiological processes govern immunity?

Answer 1

Recognition, Interaction, Response, Elimination, Control and Regulation

Question 2

What is hypersensitivity?

Answer 2

A group of disorders where the normally beneficial components of the immune response act in an exaggerated or inappropriate way

Question 3

How many types of Hypersensitivity are there?

Answer 3

5

Question 4

What is Type I Hypersensitivity usually referred to as?

Answer 4

Allergy

Question 5

What immunoglobulin proteins are responsible for Type I Hypersensitivity regulation?

Answer 5

IgE

Question 6

List some Mast cell preformed mediators

Answer 6

Histamine, heparin, tryptase, chymase eosinophils/neutrophil chemotactic factors.

Question 7

List some Mast cell newly synthesised mediators

Answer 7

Prostaglandins and leukotrienes

Question 8

Describe the action of Type I Hypersensitivity

Answer 8

Allergen - Mast cell +IgE - Degranulation - Synthesis of new mediators -

Vasodilatation, secretion, SM contraction, mucosal oedema, capillary leakage

Question 9

What immunoglobulins regulate Type II Hypersensitivity?

Answer 9

IgG and IgM mediated

Question 10

What is Type II Hypersensitivity referred to as?

Answer 10

Cytotoxic Hypersensitivity

Question 11

What is the mechanism of Type II Hypersensitivity?

Answer 11

An antigen binds to a receptor and recognises it as foreign

Question 12

What is Type III Hypersensitivity called?

Answer 12

Immune complex disease

Question 13

What is the action of Type III Hypersensitivity?

Answer 13

Excessive/Abnormal immune complex formation which leads to complement activation and recruitment of inflammatory calls - ultimately leading to tissue damage

Question 14

If Type III immune complexes form in the circulation what is this known as?

Answer 14

Serum sickness

Question 15

If Type III immune complexes form locally in the tissues what is this known as?

Answer 15

Arthus Reaction

Question 16

What is Type IV Hypersensitivity called?

Answer 16

Delayed-type

Question 17

What is the mechanism of Type IV?

Answer 17

Helper Tcells are activated by antigen presenting cells - in the future when Th1 memory cells are re-exposed to the antigen - a large inflammatory response occurs

Question 18

Type V Hypersensitivity is also called what?

Answer 18

Autoimmunity disease

Question 19

What are autoimmune diseases?

Answer 19

A large group of clinical disorders which are characterised by tissue or organ damage mediated through aberrant immunological mechanisms which are directed against autoantigens

Question 20

Tolerance of self is a key part of autoimmunity - what two aspects of tolerance are there?

Answer 20

• Central (positive vs. negative selection)

- Peripheral (T-regulatory cells, antibody regulation, immune complex formation, oral tolerance and Th17 cells)

Question 21

What is the generalised aetiology of autoimmune disease?

Answer 21

Genetic factors, immune regulatory factors, hormonal factors, environmental factors

Question 22

What spectrum do autoimmune diseases lie on?

Answer 22

Organ-Specific vs non-organ specific