Food Allergies

Question 1

About how many Americans have food allergies?

American children?

Answer 1

12M

3M children

Question 2

Does delaying the introduction of a food, such as peanuts, reduce rates of allergy?

Answer 2

Nope, it seems to increase it.

Question 3

What’s oral allergy syndrome?

Answer 3

Eating foods, often fresh fruits and veggies -> allergic rhinitis, itchy mouth.

Question 4

What mediates the food allergies that present as anaphylaxis, uticaria, angioedema etc.?

Answer 4

IgE

Question 5

4-5 systems in which IgE-mediated allergic reactions cause symptoms?

Answer 5

Cutaneous (hives, swollen lips/tongue).
GI (nausea, vomiting, diarrhea, abdominal pain).
Respiratory (coughing, rhinitis, inability to breathe).
Cardiovascular.
Neurological

Question 6

What percentage of people with IgE-mediate reactions have cutaneous reactions? Why is this important?

Answer 6

88% - This is important because you can have someone with anaphylaxis without skin signs/symptoms (and it’s often missed).

Question 7

What’s the drug of choice for anaphylaxis?

Answer 7

Epinephrine

Question 8

What do the alpha and beta adrenergic properties of Epi each do?

Answer 8

Alpha adrenergic: Vasoconstriction, increased BP, decreased capillary leakiness.
Beta adrenergic: Relax bronchial smooth muscle, increase HR and contractility. (Beta is for breathing and beating)

Question 9

Do you have to be pre-sensitized to have IgE-mediated anaphylaxis?

Answer 9

No, but people usually are.

Question 10

4 cells involved in the IgE/anaphylaxis mechanism?

Answer 10

Th2 cells (activate B cells and Eosinophils)
IgE-producing B cells
Eosinophils (activated by IgE)
Mast cells (activated by IgE)

Question 11

How must an IgE be binding Ag in order to activate mast cells and eosinophils?

Answer 11

IgE molecules must be binding closely enough such that they cross-link IgE Fc receptors.

Question 12

How did Chase in the 1940’s simply define “oral tolerance”?

Answer 12

“Active inhibition of immune responses…” to Ag after exposure

Question 13

What are 3 cell types important to maintaining the “complex homeostasis” of immunity in the gut? (…that’s a pretty vague concept)

Answer 13

Intestinal epithelial cells (IECs)
Dendritic cells (DCs)
T regulatory cells (Tregs)

Question 14

What’s different about Ags to which people commonly have allergies?

Answer 14

They’re small, not degraded in the gut, abundant in food source.

Question 15

Do intact antigens get through the barriers of the intestinal lumen?

Answer 15

Yes, about 2% get through…

Question 16

3 pathways to Ag presentation involving the gut?

Answer 16

Intestinal epithelial cell (IECs) present Ag.
M cells transcytose Ag -> Peyer’s patches.
DCs bring Ag to lymph nodes.

Question 17

What cells are very important for down-regulating immune responses in tolerance?

Answer 17

FoxP3+ Tregs

Question 18

In mice: How do low dose and high dose tolerance happen?

Answer 18

Repeated low dose Ag -> Tregs.
High dose Ag -> clonal deletion or anergy of lymphocytes.
(in mice)

Question 19

What percentage of kids with allergies eventually develop tolerance?

Answer 19

80% - the majority

but this doesn’t seem to happen for peanut allergies

Question 20

Strategies for getting people with food allergies to develop tolerance? (name 3ish)

Answer 20

Give as much as they can tolerate, slowly increasing dose.
Block IgE?
Administer Ag through skin?

Question 21

What is FPIES? (probs won’t be on test)

Answer 21

Food protein-induced enterocolitis: Kids eat milk or grains (usually) -> violent vomiting, diarrhea, shock.