Hypersensitivity

Question 1

What is a hypersensitivity reaction?

Answer 1

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

Question 2

How many classes of hypersensitivity reactions are there?

Answer 2

Type I-IV (1 to 4)

Question 3

Which hypersensitivity reactions are associated with antibody action?

Answer 3

1 to 3

Question 4

What are Type IV hypersensitivity reactions are associated with?

Answer 4

T-lymphocytes and cell-mediated responses

Question 5

Which antibody activates complement?

Answer 5

IgG3

Question 6

What does IgG3 complement also mediate?

Answer 6

Fc mediated phagocytosis

Question 7

What does IgE antibody induce?

Answer 7

Mast cell degranulation

Question 8

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

Answer 8

Variable regions

Question 9

Which cells secrete antibodies?

Answer 9

Plasma cells

Question 10

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

Answer 10

Monoclonal antibodies

Question 11

Describe the structure of an antibody:

Answer 11

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

Question 12

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

Answer 12

Disulfide bridges

Question 13

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

Answer 13

The hinge region

Question 14

What is a type 1 hypersensitivity reaction?

Answer 14

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

Question 15

What is the immune mediator for type 1 hypersensitivity reactions?

Answer 15

IgE

Question 16

Which diseases are commonly associated with type 1 hypersensitivity reactions?

Answer 16

Asthma, allergic rhinitis, and atopic dermatitis

Question 17

What mediator is released through IgE antibodies?

Answer 17

Histamine

Question 18

Which cells secrete histamine in response to IgE antibodies?

Answer 18

Mast cells and basophils

Question 19

What is the response elicited by histamine?

Answer 19

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

Question 20

What is a multivalent environment antigen?

Answer 20

An antigen that has multiple binding sites

Question 21

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

Answer 21

Th2 CD4

B cell helper follicular CD4 T cells

Question 22

Which type of cytokines are released from Th2?

Answer 22

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

Question 23

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

Answer 23

Granulocytic cells

Question 24

What effect does IgE have on mast cells?

Answer 24

Mast cell degranulation

Question 25

What is the end product of type 1 hypersensitivity?

Answer 25

Histamine release, cytokines recruit other cells | Th2 differentiation

Question 26

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

Answer 26

Th2 and eosinophils

Question 27

Which receptor do IgE antibodies bind onto?

Answer 27

Fc Epsilon receptors

Question 28

What are type 2 hypersensitivity reactions?

Answer 28

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

Question 29

Which antibodies are affiliated with type 2 hypersensitivity reactions?

Answer 29

IgG & IgM

Question 30

What is a common RBC type 2 sensitivity reaction example?

Answer 30

Hemolytic disease of new-borns | Maternal Anti-D antibodies destroy fetal RhD+ cells.

Question 31

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

Answer 31

Membrane attack complex (MAC)

Question 32

What pathways are triggered through type 2 hypersensitivity reactions?

Answer 32

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

Question 33

What is a type 3 hypersensitivity reaction?

Answer 33

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

Question 34

What are immune complexes?

Answer 34

Non-cell bound antigen-antibody complexes

Question 35

Provide an example of a self-antigen?

Answer 35

Nuclear DNA

Question 36

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

Answer 36

Inflammation and tissue damage

Question 37

Which immune cell is associated with type 3 hypersensitivity reactions?

Answer 37

Neutrophils

Question 38

What is serum sickness?

Answer 38

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

Question 39

What is a type IV hypersensitivity reaction?

Answer 39

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

Question 40

Which immune cells are associated with type 4 hypersensitivity?

Answer 40

T cells

Question 41

What is the sensitization phase?

Answer 41

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

Question 42

What physiological process is promoted via type IV hypersensitivity reactions?

Answer 42

Inflammation

Question 43

Why does contact dermatitis cause Type IV hypersensitivity?

Answer 43

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

Question 44

Which type of hypersensitivity reactions is graft rejection associated with?

Answer 44

Type IV

Question 45

Which type of hypersensitivity reaction is TB lesion associated with?

Answer 45

Type IV

Question 46

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

Answer 46

Type II