Food Allergy and Oral Tolerance Flashcards
Symptoms of allergic reaction
stridor, vomiting, hives
How many americans have food allergies?
12 million
Which food allergies do children tend to outgrow?
wheat, milk, egg, soy
2 types of adverse food reaction
food intolerance vs food allergy
Categories of food allergy
IgE mediated, non-Ige, mixed
Oral allergy syndrome
type of IgE mediated response that involves itchy mouth and other oral allergy symptoms on consumption of fruit/tree products, short of anaphylaxis
Most patients with IgE reactions present with ___
cutaneous reactions (88%) + GI, Respiratory, multiorgan, impending doom
Can you have IgE food allergy without cutaneous reactions?
Yes –> 10%
Anaphylaxis Tx
epi pen
Epinephrine effects in allergy
- alpha adrenergic: vasoconstriction, increased blood pressure, decreased cappillary leak
- bet adrenergic: relax bronchial muscle, increase heart rate, increase cardiac contractility
- inhibit mediator release
Anaphylaxis pathogenesis
Food –> antigen presentation –> activation of Th2 and IgE B cells –> eosinophil recruitment + mast cells + antibodies
Initial response
vasodilation, vascular leakage, smooth muscle spasm
Late-phase reaction
mucosal edema, mucus secretion, leukocyte infiltration, epithelial damage, vasospasm
Oral tolerance
difference between those with and without food allergy –> state of active inhibition of immune response by prior exposure to antigen
Where can food antigens be absorbed?
stomach, small/large intestine
3 cells that mediate homeostasis of immunity in Gi tract?
intestinal epithelial cell, dendritic cells, t reg cells
Host factors that promote allergy
genetics, flora, age, gastric acidity, digestive enzymes, GI peristalsis, protective mucus layer
Antigen factors that promote allergy
dose, form, small size, glycosylation, resistance to denaturation, abundance, linear epitopes, solubility
Role of IEC in immune homeostasis
presentation of antigen by immune epithelial cells lead to inactivation of or suppression of immune response
M cell role in immune homeostasis
take up antigen and present to immune system
Role of dendritic cells in immune homeostasis
transport antigen samples to lymph nodes and present samples to T cells leading to Treg activation
Low dose tolerance (mice)
via repeated lower dose, activates Treg cells (TGFbeta/FoxP3) to prevent immune reaction
High dose tolerance (mice)
mediated by deletion or lymphocyte anergy –> shuts off immune response in a fell swoop
Failure to develop or a breakdown in oral tolerance may result in ____ responses involving ___ antibodies
hypersensitivity –> IgE
Food protein enterocolitis
delayed (2-4 hours) response to allergen presenting as shock, vomiting, diarrhea in infants especially
