IgE mediated food allergy Flashcards
food allergies
- immune response that occurs reproducibly on exposure to a given food
food intolerance
ex. lactose intolerance, reactions to food additives and preservatives, pharmacological effects of caffeine - not involved in immune system
food sensitization
- not equivalent to food allergy
most common food allergies in USA
milk egg, peanut, tree nuts
food allergies effects more that ____% and less than ____ %
2 and 10
peanuts are
legumes
risk factors of food allergies
- atopic dermatitis (eczema) - sibling with food allergy - delayed dietary introduction
atopic
hypersensitivity reaction in a location that is not exposed to the antigen
FC epsilon receptor
high affinity receptor on mast cell and basophils that binds IgE which is specific to food allergen and releases histamine which exposed
early phase reaction
minutes- vasoactive amines and lipid molecules
late phase reaction
2-4 hours cytokines that recruit pro inflammatory cells
which cytokine activates IgE?
IL-4
IgE is normally found at low/high levels in the plasma
low
mast cells
- derived from bone marrow precursors - locate din mucosal and connective tissues - express high levels of Fc epsilon receptor - granules contain preformed mediators that are rapidly released upon activation (degranulation) - histamines and enzymes (tryptase) - produced soluble inflammatory mediators (cytokines- TNF) and lipid mediators (prostaglandins and leukotrienes) - growth factor IL-3
FC epsilon receptor is composed of
1 alpha chain- IgE binding 1 beta chain and 2 gamma chains - signal transduction
basophils
- bone marrow derived - found in circulating in the blood - growth factor IL-3 - express high levels of Fc epsilon receptor - produce preformed mediators
eosinophils
- derived from bone marrow precursors - circulating in the blood - increased during allergic disease and parasite infections - growth factor IL-5
IL-3 growth factor stimulate
mast cells and basophils
IL-5 growth factor stimulates
eosinophils
mast cell activation
IgE binds FC epsilon complexness result in mast cell activation and degranulation - vasoactive amines - histamines- vasodialtion, vascular leak - lipid mediators- prostaglandins, prostacyclin, leukotrienes- intestinal hyper-motility, broncho-constriction - cytokines - inflammation - enzymes - tissue damage
symtoms with immediate exposure
symptoms with late phase
allergy test have high/low sensitivty and moderate specificity
high
in vitro IgE testing
RAST and enzyme-based immunoassays (ImmunoCAP)
oral allergy syndrome (pollen-food allergy syndrome)
present in adolescents and adults with allergic rhinitis
- IgE mediated reaction against pollen related protein in foods
food dependent exercise induced anaphylaxis
- carry epipen
delayed allergic reactions to mammalian meat
- IgE for carbohydrate galactose alpha 1 3 galactose
- 4-6 hours after consuming mammalian meat
- tick bites
