Food allergy Flashcards
What is the food allergy progression? two phases (sensitization and elicitation)
A food allergen travels from the lumen through the epithelium. It first gets picked up by an APC (allergen presenting cell). Then the APC via MHC will hold the allergin on its surface. T cell binds to the allergin and then it matures into TH2
TH2 will bind to a B cells and they will produce the antigen specific IgE. Those IgEs will travel and bind to FcERI receptors expressed on the surface of mast cells. When the allergin is detected next time, the IgE form a dimer, the mast cell releases tons of inflammatory factors
The more you get exposed to an allergen, the more specific those IgE;s will be and the crazier the response.
What are epitopes
They are the region of the protein that actually reacts with the IgE. They are barely unfolded so even with digestion they are pretty conserved. So there are certain regions of proteins that most people bind to and those where no one binds to.
So it appears sequence specific which is why there is cross reactivity.
Celiac disease, what is going on?
The allergin is gliadin a proline/glutamine rich peptide found in wheat. It strongly binds to HLA type DQ2 MHC protein which drives an immune response
The activation of the peptides by tissue transgulatmase makes the binding more potent
Transglutamase cross links with gliadin even resulting in formation of antibodies against the complex worseining the response.
The proline rich sequence makes it resistant to proteases so it is concentrated in the small intestine to drive a response
How does gut microbiome affect allergy?
The more gut bacteria, the lower the allergic response.
prebiotics are nutritents that aren’t for humans but for bacteria
Probiotics are healthy bacteria that you ingest.
It seems that a tagged bacteria in the mothers gut traveled through breast milk and into the baby’s gut.
Mothers who take antiacids were more prone to their babies getting allergy development.
How do food additives like sulfites, nitrates, nitrites, MSG and aspartamem affect food allergy?
How about hygene hypothosis?
They increase food allergy. They are kind of foreign materials that put the immune system on awareness mode. ONce the allergen presents itself, the immune system is already angered.
THe HH plays on the belief of the TH2/TH1 balance. TH2 mediates food allergy while TH1 mediates the immune response to pathogens. if a baby gets sick and exposed to bacteria, you increase the TH1 balance. If babies are too protected, you will favor the Th2 and increase allergy.
What is oral immunotherapy?
It is exposing the patient to small amounts of the allergin, over time the skin prick decreased. After 18 months specific IgE levels were lowered.
igG levels were way elevated and the thought is that you are blocking the allergin from IgG.
