Hypersensitivity and Autoimmunity Flashcards

1
Q

Define hypersensitivity.

A

A group of disorders in which the normally beneficial components of the immune response act in an exaggerated or inappropriate fashion to environmental antigens which don’t usually cause the tissue damage.

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2
Q

What is responsible for the tissue damage?

A

Exaggerated immune response.

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3
Q

What are hypersensitivity types 1, 2 and 3 mediated via?

A

Antibodies.

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4
Q

What cause type 4 hypersensitivity?

A

Inappropriate actions of T helper 1 cells

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5
Q

What is the other name for type 1 hypersensitivity?

A

Allergy

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6
Q

What is type 1 hypersensitivity caused by?

A

Inappropriate synthesis of IgE.

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7
Q

In what 4 ways can a type 1 hypersensitivity reaction be started?

A

Ingestion
Inhalation
Injection
Skin contact

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8
Q

What are allergens?

A

Antigens which cause IgE production.

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9
Q

What are the 5 factors of immunity? RIREC

A
Recognition
Interaction
Response
Elimination
Control and Regulation
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10
Q

What allows IgE to bind to Fc receptors?

A

It has an extra peptide sequences to other immunoglobulins.

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11
Q

Where are Fc receptors found?

A

On the surface of mast cells.

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12
Q

What do T helper cells do?

A

Aid B-cells in producing IgE

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13
Q

What are the 3 types of Th1 cells?

A

IL-2
Gamma - IFN
TNF

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14
Q

What are the 4 types of Th2 cells?

A

IL- 4
IL - 6
IL - 10
IL - 13

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15
Q

Define atopy.

A

A genetic tendency to produce IgE to normally innocuous, common environmental allergens.

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16
Q

Define allergy.

A

A clinical expression of the atopic tendency.

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17
Q

What % of the population suffers from allergy?

A

15-20%.

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18
Q

What are 3 specific triggers of IgE?

A
Insect venom
Pollen
Mould spores
Animal dander
Food allergens
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19
Q

What are 3 nonspecific triggers of IgE?

A
Exercise
Tobacco
Pollution
SO2
Water
Food items
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20
Q

What are the 5 symptoms of allergy and atopy?

A
Anaphylaxis
Asthma
Rhinitis and Conjunctivitis
Urticaria
Gastrointestinal
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21
Q

What is the main preformed mast cell mediator?

A

Histamine

22
Q

What are the 2 newly synthesised mast cell mediators?

A

Prostaglandins

Leukotrienes

23
Q

What mast cell causes early phase response?

A

Preformed

24
Q

What mast cell causes late phase response?

A

Newly synthesised

25
Q

What 2 things mediate type 2 hypersensitivity?

A

IgG

IgM

26
Q

What are the target antigens in type 2 hypersensitivity?

A

Self

Exogenous

27
Q

Where are the target antigens found in type 2 hypersensitivity?

A

on the surface of or fixed within cells.

28
Q

In what 4 ways does damage to tissue arise in type 2 hypersensitivity?

A

Complement activation
Fc receptor-mediated damage
Antibody dependent cellular cytotoxicity
Effects on target function i.e inhibition

29
Q

What are the 2 types of immune complex formation?

A

Normal

Pathological

30
Q

What is formed in an immune complex formation?

A

Lattice due to antigens having 2 binding sites.

31
Q

What are the 3 protective mechanisms of a normal immune complex?

A

Opsonization
Transportation
Destruction

32
Q

What causes the clinical conditions to arise in in type 3 hypersensitivity?

A

Abnormal deposition of formed antigen/antibody complexes in tissues.

33
Q

What is the process of serum sickness?

A

Immune complexes form in circulation causing systemic deposition in tissues.

34
Q

What is the process of arthus reaction?

A

Immune complexes form locally in tissues.

35
Q

What happens to immune complexes formed normally after gaining access to the blood stream?

A

Kept soluble in the blood and transported to the liver and spleen for phagocytosis.

36
Q

What is the job of Th1 cells in type 4 hypersensitivity?

A

Mediator

37
Q

In general, why do type 4 hypersensitivity reactions take place?

A

As the body’s immune system finds it hard to destroy the environmental agents causing the problem.

38
Q

What is a hapten?

A

The low molecular weight agent which has so bind to a carrier to produce an antigenic stimulus of sufficient size for a response.

39
Q

How long a delay is there is type 4 hypersensitivity?

A

48-72 hours

40
Q

The hapten is ___genous and the carrier is ___genous.

A

Exo, endo.

41
Q

Define autoimmune disease.

A

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

42
Q

What is another name for autoantigens?

A

Self antigens

43
Q

What are the two types of roles an autoantigen can do?

A

Non-organ specific

Organ specific

44
Q

Define tolerance.

A

The process whereby the immune system avoids producing damaging reactions against self antigens.

45
Q

How does central tolerance arise?

A

Deletion of autoreactive T and B cells.

46
Q

How does peripheral tolerance arise?

A

Inhibiting the activity of autoreactive cells which escape the central tolerance process.

47
Q

What is the breakdown of a tolerance process a requirement for?

A

Autoimmune disease

48
Q

What are the 5 aetiologies of autoimmune disease?

A
Genetic factors
Immune regulatory factors
Hormonal factors
Environmental factors
Other factors
49
Q

What are the 5 effector mechanisms of autoimmune disease? (Pathogenesis)

A
Cell mediated
Antibody mediated
Antibody and complement
Immune complex mediated
Recruitment of innate components
50
Q

What type of disease is organ specific?

A

Diabetes

51
Q

What type of disease is non-organ specific?

A

Connective tissue