IgE Immunity

Question 1

What is atopy?

Answer 1

A genetic predisposition to become sensitized and produce IgE antibodies in response to ordinary exposure to antigens (usually proteins).

Question 2

IgE is heavily glycosylated and has binding sites for ____ on mast cells and basophils.

Answer 2

FcεR

Question 3

What are the primary mediators (contained within mast cells and basophils) that are responsible for allergy symptoms?

Answer 3

histamine, TNF-α, and leukotrienes

Question 4

What are the 2 types of mast cells, and how are they characterized?

Answer 4

Mast cells are characterized by the enzymes they contain…

• MC Tryptase
• MC Tryptase and Chymase

Question 5

What are the cytokines secreted by mast cells?

Answer 5

IL4, IL13, IL3, IL5, GM-CSF, TNF

Question 6

Elevated serum ______ found in anaphylaxis and mast cell disorders.

Answer 6

tryptase

Question 7

True or false: Almost any protein can induce an allergic response in an atopic individual.

Answer 7

true! (but there is a trend toward proteins w/ enzymatic activity or ones that induce it)

Question 8

How are genetics related to allergic responses?

Answer 8

• 50% of children with 2 atopic parents will be atopic
• different MHC II will present different peptides that differ in their antigenic potency
• polymorphic expression of multiple genes culminate in allergic responses

Question 9

Which genetic+environmental factors promote atopy vs. non-atopy?

Answer 9

• high genetic susceptibility+”hygienic” envt=atopic

- low genetic susceptibility+less hygienic envt=non-atopic

Question 10

What is the first critical step of generating an allergic reaction?

Answer 10

cross-linking of IgE on mast cell surface

Question 11

What is the predominant route of early antigen exposure?

Answer 11

mucosal route

Question 12

Which is the only FcR that can be occupied by an antibody without antigen?

Answer 12

FcεR

Question 13

What is the late-phase reaction of an allergic response entirely dependent upon?

Answer 13

Th2 activation (causes recruitment of even more eosinophils)

Question 14

When does the early-phase rxn of an allergic response happen, and what happens during this rxn?

Answer 14

• within 15 minutes of exposure
• release of histamine, prostaglandins, leukotrienes
• direct complement activation
• CANNOT happen w/o prior exposure to allergen

Question 15

How many organs must be affected for an allergic reaction to be considered anaphylaxis?

Answer 15

more than 1 (systemic reaction)

Question 16

What are the cytokines that mediate the late-phase allergic response?

Answer 16

IL3, IL4, IL5, IL13, IL10

Question 17

What are the different routes of allergen entry?

Answer 17

intravenous, subcutaneous, inhalation, ingestion

Question 18

What are the different allergy diagnostic/confirmatory tests used?

Answer 18

• skin test (puncture, intradermal)

- allergen-specific IgE serology

Question 19

What are some ways to treat/prevent allergic disease if the allergen cannot be avoided?

Answer 19

• immunotherapy (subcutaneous w/ allergy shots or sublingual)
• monoclonal anti-IgE

Question 20

What is the idea behind subcutaneous or sublingual immunotherapy for allergies?

Answer 20

the patient will eventually develop tolerance (Tregs), causing IgE level to decrease