IgE Immunology

Question 1

IgE mediated allergic response are which type of immune reaction?

Answer 1

Type I

Question 2

Define allergy

Answer 2

A disease induced by reaction to an innocuous antigen

Question 3

Define atopy

Answer 3

A genetic predisposition to developing an IgE antibodies upon exposure to environmental allergins

Question 4

What is the relative concentration of IgE in serum?

Answer 4

Very low- consider it a cell-bound antibody found mainly at host-environmental surfaces

Question 5

Name 2 of the major mediators of an IgE response?

Answer 5

Basophils and Mast cells

Question 6

What are the two different types of mast cells?

Answer 6

Mast cells in the skin: contain tryptase and chymase

Mast cells elsewhere: contain tryptase

Question 7

What is the significance of chitin?

Answer 7

Chitin is a polysaccharide not found in mammals- it is commonly found on antigens that cause allergic reactions

Question 8

If someone is allergic to cats are they allergic to all cats? What about dogs?

Answer 8

Cats; all cats

Dogs: only certain breeds

Question 9

Discuss the connection between genetics and allergies

Answer 9

Genetics and susceptibility to allergies are linked; children of parents with allergies are more likely to have allergies

Different MHC II molecules will present different peptides that differ in their antigenic potency

Also, vaginal deliveries are protective against development of allergies

Question 10

What route of exposure is most likely to sensitize someone to an allergen?

Answer 10

Mucosal

Question 11

What is the first step in an allergic response?

Answer 11

Allergens bind to DC, stimulates Th2 response through IL4, stimulates B cells to produce IgE

IgE binds allergen and stimulates mast cells to degranulate and release histamine

Question 12

Compare the relative binding strength of IgE for its receptor (compared to IgG)

Answer 12

IgE binds Fc receptors with super high affinity as compared to IgG binding Fc receptors

Question 13

What are early events that occur following binding of IgE to mast cells?

Answer 13

Release of vasoactive mediators– within 15 minutes leukotrienes and prostaglandins are released
Direct complement activation

Question 14

Can an allergic response to something occur if there is no previous exposure?

Answer 14

No. Immune system must have already been sensitized to the allergen before you develop an IgE specific to that allergen.

Question 15

What recruits eosinophils to the site of the allergic reaction?

Answer 15

IL-5

This is the late-phase response
Eosinophils are the third major cell that regulates Type 1 hypersensitivity reactions

Question 16

What characterizes a late allergic reaction?

Answer 16

Eosinophils

IL3,4,5, 13 and 10
Eotaxin

This is completely dependent on a Th2 reaction

Question 17

What organs participate in anaphylaxis?

Answer 17

Anaphylaxis is a systemic disease

Question 18

What are the primary routes of allergen entry leading to anaphylaxis?

Answer 18

Stings, injection

Question 19

What are typical allergens that can lead to anaphylaxis?

Answer 19

Food, insect venom and drugs

Question 20

What are the main symptoms of anaphylaxis?

Answer 20

Shock, hypotension, wheezing, urticaria, angioedema

Question 21

Eczema/urticaria/angioedema affects which organ?

Answer 21

Skin

Question 22

What are the general routes of allergen exposure leading to eczema/urticaria/angioedema?

Answer 22

Contact, ingestion

Question 23

What are the main symptoms of eczema/urticaria/angioedema?

Answer 23

pruritic vesicular swollen lesions

Question 24

Allergic rhinitis and conjunctivitis affects which organs?

Answer 24

Nose and eyes- causes redness and itching of eyes and runny nose

Question 25

What are some of the typical allergens that cause allergic rhinitis?

Answer 25

Mold, animal dander, pollens and dust mites

Question 26

What is gastroenteropathy?

Answer 26

Various foods cause pain, bloating, vomiting and diarrhea in the GI tract

Question 27

What is the primary drug given to someone in anaphylaxis?

Answer 27

Epinephrine (hence the Epi pen)

Question 28

What is a skin test?

Answer 28

Scratch different allergens into the skin and measure the size/presence of a wheel produced

Question 29

What is a RAST assay?

Answer 29

Old way of testing for presence of IgE against allergens - add serum to allergen, add radiolabeled IgE

Question 30

What immunologic action is blocked by the use of anti-histamines?

Answer 30

Mediator functions- blocks ability of histamines to mediate inflammatory reaction

Question 31

What type of immune reactions require the use of corticosteroids?

Answer 31

Chronic inflammatory reactions

Question 32

How does desensitization therapy worK?

Answer 32

Injections of small amounts of a specific allergy-causing antigen are meant to desensitize the Th2 cell response to that antigen

Question 33

How do we block IgE binding to mast cells in the clinic?

Answer 33

Anti-IgE antibodies (omalizumab)

Question 34

How does immunotherapy work?

Answer 34

Several months of subcutaneous shots of an allergen are given in order to develop a Treg response to that allergen