Allergic diseases

Question 1

Allergy is the production of ____ antibodies in response to a _______ antigen.

Answer 1

IgE

protein

Question 2

The allergic condition is called ______.

Answer 2

Atopy

Question 3

What kind of reaction is an allergic reaction?

Answer 3

Type 1 hypersensitivity reaction

Question 4

Harmless environmental antigen

Answer 4

Allergen

Question 5

What are the most common symptoms of allergic reactions?

Answer 5

Asthma
Hay fever (allergic rhinitis)
Eczema (atopic dermatitis)

Question 6

People with one atopic condition are more likely to develop what?

Answer 6

Another atopic condition

Question 7

What is the atopic triad?

Answer 7

Most common symptoms of an allergic reaction.
Includes:
Asthma
Hay fever (allergic rhinitis)
Eczema (atopic dermatitis)

Question 8

Many allergies start in ______.

Answer 8

children

Question 9

Symptoms of allergies in children typically manifest as what at the beginning?

Answer 9

Eczema or a food allergy

Question 10

Allergies tend to start first on the _____ or in the ____ tract. As one ages, this will switch to affect the ________ tract, instead.

Answer 10

skin
GI
respiratory

Question 11

What is the general transition in symptoms for allergies?

Answer 11

From food allergy or atopic dermatitis, to astham or allergic rhinitis.

Question 12

Which tends to disappear faster, Food allergies or Atopic dermatitis?

Answer 12

Food allergies

Question 13

What is the first exposure or primary immune response called in allergies?

Answer 13

Sensitization

Question 14

Describe the symptoms of sensitization.

Answer 14

Absent or mild

Question 15

What B cell types are made during sensitization?

Answer 15

Long-lived plasma cells that secrete IgE antibodies

Memory IgE+ B cells

Question 16

What T cell is needed for the allergic response?

Answer 16

effector Th 2 cell

Question 17

What generates the effector Th2 cell?

Answer 17

Dendritic cell takes up allergen, migrates to secondary lymphoid tissue and presents antigenic peptides on MHC 2 to activate native Th cell.
Naive Th cell is told by the dendritic cell to become a Th2 cell.

Question 18

Which cell tells the B cells in allergies to undergo class switching to IgE class?

Answer 18

effector Th2 cell

Question 19

Describe (pathway) sensitization.

Answer 19

Allergen enters the body.
Subepithelial dendritic cell takes up allergen, leaves tissue and migrates to secondary lymphoid tissue
Presents allergen on MHC class II to naive Th cell.
DC secretes cytokines telling naive Th cell to become an effector Th2 cell.
Meanwhile, B cell has bound allergen and presents it on MHC class II to effector TH2 cell
Th2 cell secretes cytokines to cause class switching to Ige
B cell undergoes clonal expansion, get production of IgE against allergen and get IgE+ memory cells
(all of this occurs in secondary lymphoid tissue)

Question 20

Mast cells express _____ that binds IgE antibodies.

Answer 20

Fc receptor

Question 21

On a sensitized person, what is bound to mast cells?

Answer 21

allergen-specific IgE antibodies

Question 22

How do IgE antibodies reach mast cells?

Answer 22

Mast cells are in the tissues; IgE antibodies return to the tissues and bind to them.

Question 23

Where are mast cells abundant?

Answer 23

In all tissues

Question 24

What do mast cells contain?

Answer 24

Many cytoplasmic granules that contain histamine

Question 25

Re-exposure to the same allergen leads to what?

Answer 25

memory response

Question 26

The memory response is quite different from the sensitization in that there is appearance of _______.

Answer 26

symptoms

Question 27

What happens, with mast cells, during the memory response?

Answer 27

Allergen enters body again. Mast cells with bound allergen-specific IgE Abs bind to allergen. This activates the mast cell, which secretes pro-inflammatory cytokines and chemokines and it degranulates - releasing histamine into the tissue

Question 28

How quick is the activation of mast cells?

Answer 28

Occurs within minutes

Question 29

What are the outcomes of mast cell activation?

Answer 29

Release of pro-inflammatory cytokines and chemokines Pro-inflammatory cytokines activate endothelial cells which leads to inflammation Histamine binds to histamine receptors on: goblet cells --> secrete mucus Nerves --> sneezing Smooth muscle cells --> contraction

Question 30

When pro-inflammatory cytokines are released by mast cells, this causes inflammation. What are the different things that occur in inflammation?

Answer 30

Vasodilation and increased permeability Nasal congestion More anti-pollen IgE Abs enter the tissue Eosinophils enter the tissue

Question 31

What is the late phase of inflammation for allergies?

Answer 31

Proteins and cells can enter the tissue - i.e. more anti-allergen IgE enters the tissue & eosinophils enter the tissue

Question 32

Early phase inflammation is due to what?

Answer 32

Activation of mast cells - degranulation and cytokine release

Question 33

What is late phase inflammation?

Answer 33

Widespread inflammation due to cellular infiltration --> tissue damage

Question 34

Tissue damage in allergy is due to what?

Answer 34

Infiltrating eosinophils

Question 35

Eosinophils: - _______ recruit eosinophils into inflammed tissue - ____________ activate eosinophils to degranulate - release highly _____ molecules --> _____ cells

Answer 35

Chemokines pro-inflammatory cytokines toxic kill

Question 36

How many eosinophils are usually in the tissues?

Answer 36

Very few since they are toxic

Question 37

What kind of cells are killed by eosinophils?

Answer 37

Any cell in the tissue

Question 38

Allergic rhinitis - allergen inhaled into the ______ respiratory tract - activates mast cells in the ______ passage

Answer 38

upper | nasal

Question 39

Describe the process of hay fever.

Answer 39

Mast cells with IgE in nasal passage. Allergen inhaled and binds to mast cells causing them to degranulate and release cytokines and histamine. Histamine causes lots of mucus to be secreted. Later on, eosinophils enter the tissues. Also, plasma gets into the tissues, causing swelling. (this is the reason for a runny nose)

Question 40

Asthma: | - allergen enters the _____ respiratory tract

Answer 40

lower (and upper as well)

Question 41

Describe the process of asthma.

Answer 41

Mast cell with IgE binds to allergen in the lower respiratory tract Get mast cell degranulation, inflammation, mucus secretion in the LRT Smooth muscle in the LRT contracts in response to histamine - broncospasms in late stage, get widespread inflammation and eosinophils entering and causing tissue damage

Question 42

Route of entry = inhalation. | Provide the site of attack, allergic reaction and response.

Answer 42

Site of attack = respiratory tract Upper --> overproduction of mucus --> rhinitis lower tract --> bronchoconstriction --> asthma

Question 43

Route of entry = injection | Provide the site of attack, allergic reaction and response.

Answer 43

Site of attack: skin --> local inflammation --> wheal and flare reaction Bloodstream --> systemic inflammation ---> anaphylaxis

Question 44

Route of entry = ingestion | Provide the site of attack, allergic reaction and response.

Answer 44

Site of attack: GI tract --> intestinal smooth muscle constriction --> gastroenteritis (vomit, diarrhea) can also enter blood if absorbed rapidly --> anaphylaxis

Question 45

Severe, potentially life-threatening allergic reaction that requires immediate attention.

Answer 45

Anaphylaxis

Question 46

Anaphylaxis is provoked by what?

Answer 46

Any allergen that enters the bloodstream (injected directly into blood or absorbed rapidly in gut)

Question 47

How is anaphylaxis systemic?

Answer 47

Circulating allergen (and IgE antibodies) can enter all tissues, activate all mast cells resulting in inflammation and widespread muscle constriction

Question 48

How is low blood pressure achieved during anaphyalxis?

Answer 48

Due to inflammation, get increased permeability systemically causing fluid and plasma to leak into tissues, lowering blood pressure.

Question 49

What is anaphylactic shock?

Answer 49

Extreme drop in BP due to extensive fluid loss from blood vessels

Question 50

How is anaphylactic shock temporarily controlled?

Answer 50

Through administration of epinephrine through an epipen

Question 51

How does epinephrine combat anaphylactic shock?

Answer 51

Epinephrine rapidly increases BP by causing systemic vasoconstriction and relaxing smooth muscle cells

Question 52

Vast majority of cases of anaphylaxis are due to what types of allergens?

Answer 52

Food allergens

Question 53

What are the different treatments for anaphylaxis?

Answer 53

Minimize exposure to the allergen Block effector responses: (e.g. anti-histamines, inhibit degranulation, relax bronchial smooth muscle, [corticosteroids as anti-inflammatory for late-phase reaction] Allergy shots

Question 54

What is the principle of allergy shots?

Answer 54

Divert immune response from IgE to IgG

Question 55

What are the target cells of allergy shots? | How does it work?

Answer 55

Target cells are Th2 cells, want to convert to Tfh cell response. Tfh cytokines induce IgG, rather than IgE.

Question 56

How are allergies diagnosed?

Answer 56

Serum IgE levels (high during allergy) | Skin prick test

Question 57

How does a skin prick test work?

Answer 57

Inject small quantities of common allergens subcutaneously. Allergens to which the person is allergic shows local inflammation withinn minutes at the injection site - wheal and flare reaction