Download SEF_paper3_allergies

Sarah Faller
12/5/2016
Professor Hubert Bray
Paper 3: Allergies
Immune System
The immune system’s job is to defend the body and keep microorganisms, such as certain
bacteria, viruses and fungi out of the body and destroy the ones that do invade the body. The
organs involved with the immune system are called the lymphoid organs (Commins). They are
responsible for development and release of lymphocytes, a type of white blood cell that defends
the body against potentially harmful invading molecules such as allergens.
Allergies and Food Intolerance
Allergies are a consequence of the immune system overreacting to certain kinds of molecules.
However, sometimes what someone might think is a food allergy is really a food Intolerance.
When someone is intolerant to a type of food, it’s most likely because their body lacks an
enzyme necessary to break down the component in that food. For example, if someone is lactose
intolerant they are missing the enzyme lactase that breaks down the sugar in milk (Shreffler).
One can also be sensitive to a chemical in the additive food. For example, one may experience
headaches, palpitations, or numbness after eating foods that are favored with monosodium
glutamate (MSG) (Shreffler).
A true food allergy involves one’s immune system. Simply put, one’s body mistakes a normally
innocuous food as a “harmful foreign invader”; the substance triggering an allergic response is
labeled an allergen. Once the body
recognizes the allergen, the body goes
into defense mode and produces high
levels of antibodies, which are proteins,
called immunoglobulins. The human
blood contains five types of
immunoglobulin: IgA, IgD, IgE, IgG, and
IgM (Shreffler). Each antibody is
programmed to recognize a unique
foreign molecule. The majority of
allergic reactions are caused by IgE
antibodies. IgE antibodies link up with
receptors on other specialized immune
cells called mast cells. Mast cells are
found in abundance in places that are an
entry into the body. When a harmless
allergen is recognized by the IgE and is
docked on a mast cell, the mast cells instigate the “allergic reaction by releasing histamine,
tryptase, and other chemicals,” (Shreffler).
These antibodies travel to cells that release chemicals, causing the allergic reaction. Mast cells
also release proteases, a chemical that can cause tissue damage. Once the mas cell is activated,
they also produce their own cytokines, a chemical messenger that signals B cells, a type of white
blood cell, to produce more IgE, which leads to more IgE antibodies docked on the mast cell,
increasing the opportunity for inflammation to occur. Concurrently, other cytokines attract whole
blood cells to the site of the allergic response, causing local inflammation. If left alone, this cycle
can cause lasting tissue damage (Shreffler).
Allergies can develop for many different reasons. A person can be either genetically predisposed
to be allergic, or factors in one’s environment can make one more susceptible. Many times, it is a
combination of both. A child who has one parent who has allergies has a 50% risk of developing
allergies and a child who has both parents who have allergies has a 70% chance of developing
allergies (Shreffler). A child is said to be atopic if they are genetically predisposed to allergies.
However, genes alone are not enough to cause allergies. There are also environmental factors
that can cause allergies. Researchers have found a positive relationship between older siblings
and allergies since the late 1900’s (Jacewicz). One study that followed a group of British
children for 23 years found that “the more older siblings a child has, the less likely he or she will
be allergic to airborne particles like dust and pollen” (Jacewicz). Some scientists, such as Brix
Pedersen, believe that the reason for this is that the younger siblings are exposed to a wider array
of germs; kids are dirtiest when they’re the youngest and they help build their younger siblings
immune system (Jacewicz). This is consistent with the study that children in day care, who are
exposed to more germs, are less likely to develop asthma. However, some scientists believe in
another theory. Danish researchers studied 571 1 month old babies’ snot. The researchers found
that infants whose mothers had already been pregnant had a much higher level of signal proteins
associated with trigger immune response (Jacewicz). Susanne Brix Pedersen, a biologist at the
Technical University of Denmark, believes that because these proteins are not “Type 2” immune
chemicals that tripper allergic reactions, it causes cells to react to foreign microorganism in a
way different than the way a body acts to an allergy (Jacewicze). The researchers also found that
the more time that passed between pregnancies, the lower the levels of protein the child has. This
suggests that previous pregnancies can later change the chemistry inside the womb and that these
changes can revert after a long period.
Meat Allergy
In recent years, a group of people started developing severe allergies to meat for no apparent
reason. Allergists rejected the theory that the allergic reactions were caused by meat because it
was unheard of that adults could develop allergies to food that they have eaten for years. Thomas
Platts-Mills, a professor at the University of Virginia and who works for an allergy clinic, had
been hearing about this supposed allergy as early as 2004. During the same time Thomas PlattsMills was asked to investigate the cancer drug cetuximab because it was causing some people
who were injected with this drug to go into anaphylactic shock. Their immune system started to
overreact to anything that was new. Mills was able to narrow down the culprit to a particular
sugar molecule, galactose-alpha-1,3-galactose, also known as alpha-gal, a complex carbohydrate
molecule (Shreffler). This same sugar is also found in non-primate animals. Mills and his team
couldn’t figure out why after years of eating meat, some people were only recently developing an
allergy.
After extensive research Mills realized that
the people who were developing a meat
allergy were widespread in the southeast,
Mid-Atlantic, and Northeast regions of the
United States, places where there were also
a lot of people with rocky mountain spotted
fever caused by a lone star tick. The allergy
was first formally identified by Sheryl van
Nunen in her paper in 2009, as originating
from tick bites. It wasn’t until Mills
intentionally got bitten by a tick and
developed the same allergies that his team came to this surprising conclusion (McEwen).
Although it is not 100% clear what exactly the tick gives a person that makes them severely
allergic, Sheryl Can Nunen and her team have a theory (McEwen). When the tick sticks onto
someone, it injects its saliva into its victims. The spit the tick injects has anti-clotting factor, antiinflammatory factor, and many others things including alpha-gal from when it fed off other
animals (McEwen). When the body is exposed to alpha-gal, covered by all the other harmful
substances in the spit, the immune system goes into defense, and the alpha-gal gets mislabeled as
a potential threat and the body remembers that ("Alpha-gal Allergy). Then, the next time that
person eats meat, the body unleashes wave upon waves upon IgE antibodies to fight the alphagal. The abundance of antibodies can make the person feel horrible. They have the potential to
break out into hives, angioedema, itching, or even experience anaphylaxis ("Alpha-gal Allergy).
This allergy is different than most because most food allergies have been associated with
proteins. However, alpha-gal is a sugar. Another unique aspect of this meet allergy is that it is
not immediate. Most allergies to food are immediate, but a person experiencing alpha-gal allergy
doesn’t react until four to six hours after ingesting. Alpha-gal is a sugar that attaches itself to fat
molecules and the body can take about eight hours to completely absorb dietary fat from an
average meal (St. John). Before fat can be broken down and absorbed, it must undergo
processing in the stomach and pass into the small intestine. Stomach emptying, depending on the
ratio of fats, proteins and carbohydrates, can take roughly five hours (St. John).
Possible Ways of Prevention
Allergies are becoming increasingly prevalent. Currently about one in five American children
have a respiratory allergy like hay fever, and one in ten have asthma. Everyday nine people die
due to asthma attacks. While the increase in respiratory allergies seem to be plateauing, food and
skin allergies are continuing to rise (Velasquez-manoff). In the last 15-years the percentage of
children allergic to peanuts, milk and other foods has doubled. In addition, each new generation
seems to have more severe, life-threatening allergic reactions than the last (Velasquez-manoff).
The reasons for this can’t all be genetic. For example, the Amish, who in the northern region of
Indiana are remarkably free of allergies and asthma. The Amish originally came to America from
the German-speaking religion of Switzerland, and currently Swiss children, a genetically similar
population, are about as allergic as the average American (Velasquez-manoff). 92% of the
Amish children were either living on a farm or visited a farm frequently; this could be the secret
of the Amish (Velasquez-manoff). In addition, 80% of the Amish that the scientists studied
consumed unpasteurized milk (raw milk). These children had more regulatory T-cells. The more
T-cells one had, the less likely these children were to be diagnosed with asthma (Velasquezmanoff). Scientists believe that the problem is the increasing sensitivity to whatever allergens are
already present in the environment. This could suggest that little exposure to potential allergens
is critical for strengthening the immune system.
Another experiment that supports this claim is an experiment done with peanuts. Peanuts can
cause a severe and possibly deadly allergic reaction. In fact, peanuts are the top food allergens in
America. However, according to The New England Journal of Medicine, there is one hope for
people who have peanut allergies: peanuts. For this study, a group of international researchers
gathered infants who had an allergic reaction that affects the skin such as an egg allergy or
eczema. Both can be indicators that the child is prone to a peanut allergy (Shreffler). Then the
children who divided into two random groups. One group of children didn’t consume any
peanuts or any peanut-based product until the age five. The other group of infants were fed a
peanut-based snack called Bamba or peanut butter three times a week until the age of five. The
results were outstanding. Only 1.9% of children who were exposed to peanuts developed a
peanut allergy, while 13.7% of the kids who weren’t exposed to peanuts developed a peanut
allergy (Shreffler). It’s clear that the young immune system adapted to the proteins in peanuts so
that they didn’t overreact to the innocuous proteins. Israeli children are exposed to peanuts at a
much earlier age than British children. Consequently, the risk of peanut allergy was 10 times
higher in the British children than in the Israeli children.
However, this doesn’t necessarily suggest that at a late age, one should try to expose themselves
to everything they are allergic too, encountering it intermittently may push one into overdrive,
prompting the misery one is attempting to avoid (Velasquez-manoff). A prospective study from
Denmark does suggest that it is never too late no matter what age.
Conclusion
There is still a lot that is unknown about allergies. However, one thing that most scientists can
agree on is that kids should not be overly protected from germs. It is important to let the immune
system develop and strengthen.
Work Cited
"Alpha-gal Allergy." Wikipedia. Wikimedia Foundation, n.d. Web. 06 Dec. 2016.
Commins, Scott P., and Thomas A. E. Platts-Mills. "Delayed Anaphylaxis to Red Meat in
Patients with IgE Specific for Galactose Alpha-1,3-Galactose (alpha-gal)." Current
Allergy and Asthma Reports. U.S. National Library of Medicine, Feb. 2013. Web. 06
Dec. 2016.
JACEWICZ, NATALIE. "Asthma-Free With No Hay Fever? Thank Your Older Sibling." NPR.
NPR, n.d. Web. 06 Dec. 2016.
McEwen, Annie. "Alpha Gal." Radiolab. RadioLab, n.d. Web. 06 Dec. 2016.
Shreffler, Wayne, PhD. "Was It Something I Ate? Understanding Food Allergies." (n.d.): n. pag.
Harvard Health. Web.
St. John, Tina M. "How Long Until Fat Is Absorbed From Food?" LIVESTRONG.COM. Leaf
Group, 18 Aug. 2015. Web. 06 Dec. 2016.
Velasquez-manoff, Moises. "A Cure for the Allergy Epidemic?" The New York Times. The New
York Times, 09 Nov. 2013. Web. 06 Dec. 2016.