Allergies or hypersensitivity is an overreaction to a foreign substance that wouldn't occur in a normal individual; a very subjective definition at best. They are either acquired or inherited or both; either way, they can ruin your day.
An allergy is nothing to sneeze at. Well, actually it is. What should be a protective response becomes a dangerous response and can range anywhere from a runny nose to a potentially fatal event.
Hypersensitivity of the immune system is very similar to an overreaction of the inflammatory response.
With infectious agents, we look for antigens; so it follows that with an allergy, we would look for an allergen.
Graphic left: schematic of how an antibody binds with its corresponding antigen or allergen by a docking mechanism. Source: Original work of U.S. Government; color enhanced version provided by Fvasconcellos, 6 May 2007, public domain.
Allergens produce allergic reactions and foods are a major culprit. To many people, milk is an allergen, as are peanuts, eggs and shellfish. What all these have in common is that they are foreign proteins and to some people foreign proteins are invaders to be vanquished.
As it turns out, that is the main concern about the influx of genetically modified foods into our diets; they introduce foreign proteins into our body that our immune system does not recognize. More on GMO's later.
Antibiotics can be very allergenic to some people. Various types of venom are extremely troublesome; such as venom from ant and bee stings, snake bites, and jellyfish. All cause a wide range of reactions.
As with all allergic reactions, a prior exposure is required.
Graphic below: The process flow from first exposure of an allergen, ragweed in this case, to creation of antibodies, attachment of antibodies to a Mast Cell and release of chemicals upon subsequent exposures. Source: National Institutes of Health (NIH), Sept. 2003, public domain.
At one time, vaccines could cause allergic reactions because they had to be grown in something like eggs, horses or cows but now most vaccines are artificially grown in the lab.
It wasn't the vaccine causing the problem but the medium it was grown in; more foreign proteins.
Lastly there are chemical and bio-allergens like poison ivy or mango skins. Feces of dust mites in the home are very problematic.
Some chemicals in medicines cause allergic reactions. Iodine in radiological treatments can affect some people. Thiomersal (or thimerosal if you live in the U.S.), a preservative that used to be prevalent in vaccines, has been under suspicion as a cause for increases in autism.
If you want a more complete description of how allergies manifest themselves than is shown in the cartoon illustration above, click on the book cover, The Allergy Epidemic to see if it belongs in your library.
Let's see how allergies can manifest themselves.
If it seems that more and more people are now suffering from allergies, it is because they are.
Pediatricians and allergy specialists across the country report that allergic reactions in children are rising at an unprecedented rate.
Parenthood.com reports that Dr. Marc Rothenberg, M.D., Ph.D. and head of Allergy and Clinical Immunology at Children's Hospital Medical Center in Cincinnati states that in the past five decades, there has been tremendous growth in the incidence of all immune-based diseases with allergies and asthma just being the tip of the iceberg.
Pediatric allergist Gail Shapiro, M.D. also confirms the rise in allergies in children. She says that 30 years ago it was rare for a child to be hospitalized for asthma.
Today, asthma, which is a complication of an allergy, is one of the most common reasons for hospitalization among children. About 500,000 children are hospitalized each year from asthma with about 2 million a year being treated in emergency rooms.
Allergies in children are up across the board; from rhinitis to food allergens in food to allergic dermatitis. Allergic rhinitis now affects 40% of all children in the U.S.
Food allergies are rising fastest of all. In the ten years from 1997 to 2007, there was an 18% increase in allergic reaction to food in children.
Why would reactions to food be increasing so fast? We weren't allergic to our food 20 or 30 years ago so what has changed? Why aren't food allergies in kids going up as fast in Europe or Asia? Why is the U.S. such a hot spot for allergic reactions to food?
The short answer may be that genetically modified corn, soy, dairy cattle, growth hormones and food additives weren't present in our food chain years ago.
In the quest for profits, food companies have introduced an incredible amount of foreign proteins into our bodies that our immune system views as invading organisms and reacts accordingly.
Robyn O'Brien is on the right track. She is the "Erin Brockovich" for food safety and is working very hard to come down on the food companies and seed companies that may be the root of the problem.
Watch Robyn's lecture on the embedded You Tube video below, courtesy of the TED lecture series from Austin, and learn how the big food companies and government agencies that are supposed to regulate them are sabotaging our kids health. There's no better reason to eat "organic".
According to Dr. Sami L. Bahna, professor of pediatrics and medicine and Chief of Allergy and Immunology at Louisiana State University Heatlth Center, it's not just the numbers, "the severity of food allergies is going up".
There have been large increases in severe allergic rashes, allergy caused airway obstruction (anaphylaxis) and allergic intestinal problems.
Something has clearly gone wrong but no one seems to know why.
Conflicting theories abound so let's look at a few.
If I were a doctor, I probably wouldn't have used the word "beserk" but it seems to fit. Hypersensitivity would be more appropriate or maybe hyper-inflammatory reaction.
The names of most of these allergic reactions seem to end in "itis" which means "inflammation"; rhinitis, dermatitis, sinusitis and so on.
One theory is that we are too clean these days. The reasoning is that our very young kids are so overprotected from germs and environmental agents that their immune systems never get a chance to learn to differentiate between friendly and harmful substances.
So instead of a benign reaction to common things like dust or pollen, the immune system goes on the attack full bore.
Another theory is that allergies are on the rise because our homes are too dirty; that is, polluted from an increase in airborne pollutants. The tight construction of homes coupled with poor ventilation causes rising levels of indoor allergens.
One theory blames it on global warming; another on genetic factors.
Another line of reasoning is that allergies are rising due to poor nutrition in young people. If I had to pick one, I think this would be it.
Cellular communication and identification are the keystones of the immune function. Both depend on the presence of certain sugars the cell needs to construct the glycoproteins and glycolipids used in cell signaling.
For many reasons, these vital nutrients are largely missing in today's diet.
These are the most deadly and start in the circulatory (humoral) system after being triggered by an antibody known as immunoglobulin IgE.
The allergen is usually a protein and the reaction time is in seconds to minutes. There must have been a prior exposure in order for the body to recognize the allergen.
During the first exposure there will be no reaction but watch out for that second exposure. In scientific jargon the second exposure is called the amnestic response and happens very quickly and is extreme and that is the problem.
Anaphylactic shock results in the release of histamines, leukotrienes and prostaglandins; all of which are inflammatory messengers.
The manifestations can include nasal dilatation, itching, edema (fluid in tissues), smooth muscle contraction from leukotrienes and prostaglandins, phlegm, pulmonary edema, abnormal heart rhythm, abdominal cramps, shock and death unless treated immediately.
This is the immune system waking up an inflammatory response.
The treatment is to inject epinephrine (adrenalin) which will rapidly restore breathing and normal heartbeat.
An "Epipen" is used to inject epinephrine. An antihistamine is the second line of defense with corticosteroids being the third line of defense.
These reactions are initiated in the circulatory system by two other antibodies labeled as the IgG and IgM immunoglobulin.
They occur when our own antibodies attack antigens on our own blood components or tissues, such as would happen with an incompatible blood transfusion.
Each blood type has different antigens thus transfusing the wrong blood type into someone could be a fatal mistake. The antibodies break open the blood cells, a condition known as hemolysis. We can't blame the antibodies, they are just doing their job. What we have is a failure to communicate.
These type III reactions involve the IgA or IgM antibodies. Occasionally groups (or complexes) of joined antibodies and antigens will escape being eaten by phagocytes (white blood cells) or being engulfed and walled-off by the cell membrane.
When this happens, they can lodge in the thin layer of fibrous tissue just under the outer cellular lining, called the epithelium, of our skin, organs and cavities of the body. Since this layer of tissue is under the epithelium, it is logically called the "basement membrane" and once they become lodged in it, they will destroy the membrane's cells by creating an inflammatory response.
Good examples are rheumatoid arthritis and strep throat. Given that a function of the basement membrane is to help anchor the cells epithelium (think of skin) to its underlying tissue, it's not good when the "anchor" breaks loose.
Type IV reactions begin in the cell, as opposed to the circulatory system, and can take anywhere from 12 to 72 hours for symptoms to start being felt. Allergens are taken up by cells with the appropriate receptors and then move to lymph nodes where they induce the production of white blood cells called lymphocytes, also known as T-cells since they reach maturity in our thymus gland.
The newly produced T-cells return to the cell which originally docked with the allergen where they cause an inflammatory response by stimulation of macrophages and signaling molecules called tumor necrosis factor, or TNF, that can cause cell death.
Common causes are tuberculosis, poison ivy and rejection of a tissue graft by the host.
Testing to identify the cause of an allergic reaction is centered on either skin or blood.
Pin prick or skin puncture is still the most common procedure used to identify allergen specific antibodies. Advantages are that it is more specific, less expensive and simple to administer.
Very small amounts of the suspected allergen are placed on the skin at the pin prick sites and, typically, an inflammatory reaction will appear in 30 minutes or so if the person is allergic to the substance.
There are several blood testing approaches in use to identify problem allergens. The RAST for "radioallergosorbent test" has been in use for many years and uses antibodies labeled with radioactive isotopes to quantify the levels of IgE antibody in the blood. Other allergic reaction blood tests are based on colormetric or flourometric technologies.
Once the cause of an allergic reaction has been isolated, the first and most logical action is avoidance. Unfortunately this is easier said than done for many allergens.
Where food is the culprit, avoidance is possible except where the stealth factor comes in. Allergenic proteins can show up in some unexpected places, especially in processed foods. Milk or other dairy products are used in many foods. Peanut oils or extracts can also be present when least expected.
Avoidance of animal dander is possible until we pay a visit to someone who has three dogs or cats in the house.
With environmental allergens such as pollen, mold, fungi and the like, avoidance may be out of the question. Nevertheless, keeping the house vacuumed, dusted, washing bedding and towels frequently and using air filters can reduce the frequency and severity of allergies in the home. Special care should be taken in sleeping areas to keep the dust mites at bay.
For many people, pharmaceutical companies have come to the rescue with various drugs designed to block the action of substances that trigger an allergic reaction by preventing the activation of cells and subsequent degranulation.
These include a wide range of antihistamine products (Zyrtec), decongestants (Sudafed, Mucinex), cortisone, leukotriene inhibitors (Singulair), steroid nasal sprays; the list is endless.
Immunotherapy is often used to mitigate the allergic reaction by attempting to desensitize the body to the specific allergen. This approach involves a series of shots or vaccinations starting with very small doses of the allergen and building up to larger infusions.
The hope is that the body will respond by producing antibodies to the allergen and thus decrease or eliminate the allergic reaction.
The first knee-jerk reaction from the medical community is to look for a new drug and the pharmaceutical companies are always happy to oblige.
The big breakthrough is that a new class of drugs called "anti-IgE" therapies show promise in treating rhinitis, food, skin and asthma type allergies.
One such drug that should hit the market soon is Xolair, assuming the FDA approves it. But guess, what? It will likely cost you $10,000 a year and insurers are not likely to cover it for allergies.
Wouldn't it be so much better to see our research dollars go toward prevention and nutrition instead of investing hundreds of millions of dollars on a new drug that no one can afford? Let's figure out how not to get an allergy in the first place.
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