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Mechanisms of human disease > food allergies > Flashcards

Flashcards in food allergies Deck (14):
1

On the whole, what is there an increase or decrease in food allergy prevalence in the developed world?

There is an exponential increase in food allergy prevalence in the world.

2

What are the determinants of allergic diseases?

A combination of genetics and early life environment affect allergic diseases. Microbial exposure during early childhood is a very important determinant for the prevalence of food allergy.

3

How does a lack of microbial exposure during childhood increase the likelihood of developing food allergy?

In mice, it has been proven to lead to underdeveloped peyer's patches (lymph nodes in the gut), less IgA plasma cells and CD4+ t cells in the intestinal wall, and a reduced number of intraepithelial lymphocytes within the gastric mucosa. These factors lead to failed oral tolerance and a Th2 response to foods, leading to food allergy.

4

How is the intestinal microbiota different in children with food allergies?

Children with food allergies have lower probiotic bacteria levels and higher levels of pathogenic bacteria in the gut. Thus, by ensuring that a child has the correct types and amounts of intestinal bacteria would be the key to preventing food allergies.

5

Is food allergy more prevalent in children or adults?

Children. Food allergies tend to be resolved in adulthood.

6

What are the 8 major food groups that are responsible for more than 90 percent of the food allergies in the population?

Cow's milk, eggs, peanuts, tree nuts, wheat, soya beans, shellfish (charity) and fish.

7

What is the difference between food allergy and food sensitization?

Some children may have a pathological response to a food when consumed, but without any allergic symptoms. This is when IgE antibodies are released after eating a food, but the individual doesn't have any symptoms or only mild symptoms.

8

which of the food groups induce allergies that remain throughout life and which ones are only during childhood?

Childhood only: egg, wheat, milk, soy
Adulthood (lifelong): shellfish, fish, peanuts and tree nuts.

9

What are the types of symptoms experienced as a result of food allergy?

Urticaria (a rash like hives), angioedema (swelling and puffiness of the eyes). There may also be airway constriction, coughing and cardiovascular effects, all of which are IgE mediated.

10

How are food allergies managed?

Mainly through avoidance, but it is not very effective outside of the home, because food preparation in public can't be controlled. This is where most of the fatal food allergy deaths occur. Epipens can be administrated to stop an anaphylactic reaction, but they are often administered incorrectly.

11

Food allergies are defined as an immunological loss of tolerance. What is the immune system doing wrong in a person with food allergies?

The immune system, in response to a harmless food, will initiate a Th1 response, leading to the production of the IgE antibody. This is an immunological response to the bacteria and viruses that have invaded the cells and so it is inappropriate. A person without food allergies is more likely to initiate a Th1 response, which leads to no antibody production.

12

What would be the pathological way to cure food allergies?

The immune system needs to have increased allergen-specific Treg cells, because the Treg cells will decide if the food is an immunological threat or not. The absence of, or presence of underdeveloped Treg cells in allergic individuals results in food allergy.

13

In terms of food allergy therapy, what is the difference between food desensitization and food tolerance.

Food desensitisation is when a food is able to be tolerated if it is administered in small, but regular doses. It is reversible if the small but regular doses are stopped.
Tolerance is the ability to tolerate a food long after the small, but regular doses of the food have stopped being administered. This occurs because Treg cells have learned to recognise the food as harmless.

14

Pathologically, what does food therapy do to reduce food allergy?

Food therapy works by reprogramming the Treg cells to induce a Th1 response to the food, rather than a Th2 response which is allergic. Food therapy teaches the Treg cells to induce a Th1 response, which leads to TGF-beta and IL-10 secretion. This leads to a blocked Th2 pathway and the production of IgG4 and IgA antibodies, which do not induce all the allergic symptoms of IgE and is a normal response to food.