Hypersensitivity Flashcards

1
Q

What is a hypersensitivity reaction?

A

An immune reaction against self-antigens resulting in autoimmune disease.
Excessive undesirable reactions

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2
Q

How many classes of hypersensitivity reactions are there?

A

Type I-IV (1 to 4)

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3
Q

Which hypersensitivity reactions are associated with antibody action?

A

1 to 3

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4
Q

What are Type IV hypersensitivity reactions are associated with?

A

T-lymphocytes and cell-mediated responses

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5
Q

Which antibody activates complement?

A

IgG3

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6
Q

What does IgG3 complement also mediate?

A

Fc mediated phagocytosis

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7
Q

What does IgE antibody induce?

A

Mast cell degranulation

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8
Q

Which antibody region is complementary to the antigenic structures present on pathogens?

A

Variable regions

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9
Q

Which cells secrete antibodies?

A

Plasma cells

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10
Q

What is the term referred to as the clone of plasma cells secreting specific antibodies in response to a particular antigen?

A

Monoclonal antibodies

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11
Q

Describe the structure of an antibody:

A

2 heavy chains held together by disulfide bridges, connected to 2 light chains via a hinge region, considered as the antigen-binding site;

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12
Q

How are the two heavy chains present within antibodies held together?

A

Disulfide bridges

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13
Q

Which region of the antibody is considered to be the antigen-binding site?

A

The hinge region

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14
Q

What is a type 1 hypersensitivity reaction?

A

Anaphylactic/immediate hypersensitivity: Provoked allergic reaction by re-exposure to a specific antigen- allergen

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15
Q

What is the immune mediator for type 1 hypersensitivity reactions?

A

IgE

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16
Q

Which diseases are commonly associated with type 1 hypersensitivity reactions?

A

Asthma, allergic rhinitis, and atopic dermatitis

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17
Q

What mediator is released through IgE antibodies?

A

Histamine

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18
Q

Which cells secrete histamine in response to IgE antibodies?

A

Mast cells and basophils

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19
Q

What is the response elicited by histamine?

A

Vasodilation
Inflammatory response
Cell diapedesis (Increasing capillary permeability and accumulation of fluid within the interstitial space)

20
Q

What is a multivalent environment antigen?

A

An antigen that has multiple binding sites

21
Q

Which type of helper cells are generated during type 1 hypersensitivity reactions?

A

Th2 CD4

B cell helper follicular CD4 T cells

22
Q

Which type of cytokines are released from Th2?

A

Type 2 cytokines IL-4 IL-13, Binds onto complementary receptors on B cells promoting B cell activation to produce antigen-specific IgE

23
Q

Which cells express high-affinity IgE receptor(FC epsilon receptors)?

A

Granulocytes

24
Q

What effect does IgE have on mast cells?

A

Mast cell degranulation

25
Q

What is the end product of type 1 hypersensitivity?

A

Histamine release, cytokines recruit other cells

Th2 differentiation

26
Q

Which cells are present at the later stages of a type 1 HS?

A

Th2 and eosinophils

27
Q

Which receptor do IgE antibodies bind onto?

A

Fc Epsilon receptors

28
Q

What are type 2 hypersensitivity reactions?

A

Antibody-mediated cytotoxic; destruction of body cells by IgG/IgM antibody bound to antigens present on cell surface membranes

29
Q

Which antibodies are affiliated with type 2 hypersensitivity reactions?

A

IgG & IgM

30
Q

What is a common RBC type 2 sensitivity reaction example?

A

Hemolytic disease of new-borns

Maternal Anti-D antibodies destroy fetal RhD+ cells.

31
Q

What complement complex is formed upon antibody bound cell surface membranes?

A

Membrane attack complex (MAC)

32
Q

What pathways are triggered through type 2 hypersensitivity reactions?

A

Antibody-dependent cell-mediated cytotoxicity: Cell lysis
Classical activation of the complement cascade
Lectin pathway

33
Q

What is a type 3 hypersensitivity reaction?

A

Immune complex driven, arise from failed clearance of antibodies reacting against self-antigens
Immune complexes are removed by the immune system

34
Q

What are immune complexes?

A

Non-cell bound antigen-antibody complexes

35
Q

Provide an example of a self-antigen?

A

Nuclear DNA

36
Q

What is promoted via the failure of the clearance of immune complexes?

A

Inflammation and tissue damage

37
Q

Which immune cells are associated with type 3 hypersensitivity reactions?

A

Neutrophils+Macrophages

38
Q

What is serum sickness?

A

Anti-serum (Antibodies specific to snake venom protein) are attacked by antibodies made by the body

39
Q

What is a type IV hypersensitivity reaction?

A

Delayed T cell-mediated hypersensitivity is initiated by sensitized T cells.

40
Q

Which immune cells are associated with type 4 hypersensitivity?

A

T cells

41
Q

What is the sensitization phase?

A

Antigens are presented to Naive t cells by antigen-presenting dendritic cells, results in the generation of antigen-specific memory T cells.

42
Q

What physiological process is promoted via type IV hypersensitivity reactions?

A

Inflammation

43
Q

Why does contact dermatitis cause Type IV hypersensitivity?

A

Urushiol drives a T-helper create mem cells in 1st response, re-exposure results in memory cells producing cytokines (IFN gamma), promotes inflammatory activation of macrophages and causes edema.

44
Q

Which type of hypersensitivity reactions is graft rejection associated with?

A

Type IV

45
Q

Which type of hypersensitivity reaction is TB lesion associated with?

A

Type IV

46
Q

Which type of reaction is Graves’s disease associated with?(Consider thyroid-stimulating antibodies)

A

Type II