Allergic Disease

Question 1

Hypersensitivity

Answer 1

Undesirable, damaging or discomfort producing reactions produced by the normal immune system, directed against inocuous antigens in a pre-sensitised (immune) host

Question 2

Type II hypersensitivity

Answer 2

Cytotoxic

Question 3

Immunopathogenesis of Type II hypersensitivity

Answer 3

IgG/IgM Ab response against combined self/foreign antigen at the cell surface-complement activation/phagocytosis.

Question 4

Clinical features for type II hypersensitivity

Answer 4

Mins to hours. Cell lysis and necrosis.

Question 5

Common antigen for type II hypersensitivity

Answer 5

Penicillin

Question 6

Associated diseases with type II hypersensitivity

Answer 6

erythroblastosis fetalis, goodpasture’s nephritis. Rh reaction with mother/foetus.

Question 7

Type III hypersensitivity reaction

Answer 7

Immune complex

Question 8

Immunopathology of type III hypersensitivity reaction

Answer 8

IgG/IgM Ab against soluble antigen-immune complex deposition.

Question 9

Clinical features of type III hypersensitivity

Answer 9

Onset 3-8 hours. Vasculitis.

Question 10

Traditional cause for type III hypersensitivity reaction

Answer 10

Serum sickness

Question 11

Associated diseases for type III hypersensitivity reaction

Answer 11

SLE

Question 12

Type III reaction to IV route of antigen

Answer 12

Vasculitis, arthritis, nepthritis

Question 13

Type III reaction to SC route of antigen

Answer 13

Arthus reaction-perivascular area

Question 14

Type III reaction to inhaled route of antigen

Answer 14

Farmer’s lung

Question 15

Type IV hypersensitivity reaction

Answer 15

Delayed- no Ab involved

Question 16

Immunopathology of type IV hypersensitivity

Answer 16

Antigen specific T cell mediated cytotoxicity

Question 17

Clinical features of type IV hypersensitivity

Answer 17

Metals e.g. nickel (tuberculin reaction)

Question 18

Associated diseases of type IV hypersensitivity

Answer 18

Contact dermatitis

Question 19

Immunopathology of type 1-anaphylaxis IgE mediated hypersensitivity

Answer 19

Increased IgG levels
Tissue inflammation with eosinophils, mastocytosis, basophil infiltration.
Presence of CD4 cells secreting Il4, Il5, Il13

Question 20

Hygeince hypothesis

Answer 20

More exposure to infections, less allergies. Mechanisms is Th1-Th2 deviation (Th1-infection, Th2-allergy)

Question 21

Association between genetics and rhinitis

Answer 21

None, as opposed to asthma and atopic dermatitis

Question 22

What happens to the T cell activation in allergic reactions

Answer 22

Treg pathway suppressed, Th1 and Th2 pathways are activated.

Question 23

IgE Abs are induced by which cytokines?

Answer 23

Il-4

Question 24

Sensitisation

Answer 24

B cells activated by Th2 cells-produce IgE Abs, induced by Il-4 cytokines

Question 25

What happens when an allergen is in contact with a pre sensitised host?

Answer 25

Antigen binds to fab region of IgE on sensitised mast cell, triggering the release of vasoactive amines.

Question 26

Immunopathogenesis of type I hypersensitivity

Answer 26

IgE Ab mediated mast cell and basophil degranulation-release of preformed and de novo synthesised inflammatory mediators.

Question 27

Clinical features of tyep I hypersensitivity

Answer 27

fast onset (15-30 mins) wheal and flare

Question 28

Late phase response of type I hypersensitivity

Answer 28

Eosinophils, central role for Th2 T cell

Question 29

Describe the initial response of the mast cell in type I hypersensitivity, following antigen binding to IgE on surface of mast cell

Answer 29

Degranulation-histamine, proteases, chemotactic factors

Question 30

Describe the late phase reponse of mast cell activation in type I hypersensitivity

Answer 30

Cytokines | Arachidonic acid-leukotrienes and prostaglandins

Question 31

3 roles of the Th2 cell

Answer 31

Activates B cells-drives Ab production Activates macrophages-innate inflammatory response Activates other cells-multiple cytokine release

Question 32

3 parts of the atopic triad and what form of hypersentivity each of them are

Answer 32

Rhinitis- 1 Asthma- 1 Atopic dermatitis- 4

Question 33

Is astham in the upper or lower airways?

Answer 33

Lower

Question 34

Which cytokine triggers pruritis (scratch)

Answer 34

IL-31

Question 35

Anaphylaxis

Answer 35

Acute, potentially life threatening, IgE mediated systemic hypersensitivity reaction. 3 types- 3 most severe.

Question 36

Allergic status is given if you have a specific IgE level of what?

Answer 36

greater than o.35kua/L

Question 37

What is positive result for the skin prick test?

Answer 37

>3mm wheal

Question 38

Describe the skin prick test

Answer 38

-ve control: saline solution (shouldn't react) +ve control: histamine (everyone should react) Pollen/potential antigen

Question 39

Describe the basophil activation test

Answer 39

If sensitised, basophils will be activate by antigen -blood test

Question 40

4 types of tests for allergices

Answer 40

Skin prick test Intra-dermal test Oral challenge Basophil activation test

Question 41

Mechanisms of immunotherapy

Answer 41

Switching pathways from Th2-Th1 or inducing Treg pathway. Modifying T cells to activate B cells to make different antibodies.

Question 42

Describe the skin prick test

Answer 42

-ve contcol e.g. saline solution +ve control e.g. histamine Potential antigen +ve result if greater than 3mm wheal

Question 43

Name 4 allergy tests

Answer 43

Skin prick test Intradermal test Oral challence Basophil activation test (blood test)

Question 44

Mechanisms of immunotherapy

Answer 44

Switching pathways Th2-Th1 or inducing Treg pathway. | Modifying T cells to activate B cells to make different antibodies