Allergy Basics – The Overreaction Explained
Allergies can seem like a mystery. A person can be walking along minding their own business when out of nowhere, a breath of pollen-filled air can leave them sneezing, reaching for tissues and wondering what just hit them. If you suffer from allergies this is a familiar scenario. Over the course of your day you may see television commercials depicting people dancing in meadows after taking allergy medicine or advertisements in the newspaper about testing and desensitization. But what are allergies? What is the difference between an allergy, an intolerance and a sensitivity? Do natural allergy treatments really work and if so, how do they work? This article, and the one to follow, will clarify the basics of allergies and allergy treatment options so that you can make an informed choice about allergies for you and your family.
The body's immune system is designed to respond to dangerous intruders like viruses and bacteria. It is a well synchronized system of cells, antibodies and chemicals that act and respond as necessary to clear out pathogens and protect us from harm. Unfortunately, sometimes it can react to a harmless substance like food, pollen, mold, animal dander, dust, metals or chemicals. The substance it reacts to, and often overreacts to, is called an allergen and these substances enter the body through inhalation, swallowing or with direct skin contact. The body's areas of first exposure to allergens are typically the nose, mouth, skin, eyes, lungs and stomach. When there is a reaction by the immune system it is these areas that become a battleground. Your allergy symptoms are a sign of that battle.
The following description is for the type of reaction we would see in seasonal allergies, pet allergies and some food reactions. This type of reaction is called a Type I hypersensitivity reaction. This means it is immediate (as anyone who has cat allergies can attest to once the cat climbs up onto your lap), involves IgE antibodies, and has early and late phases of reaction. Upon an initial exposure to the allergen such as pollen, food or pets, the body produces antibodies of the IgE type and these antibodies attach to a cell called a mast cell. These cells are found in places like our airways and intestines. With subsequent exposure, a portion of the allergen called an antigen will then bind to the IgE antibodies that are attached to the mast cell and cause the mast cell to release several chemicals into the blood. The main chemical that causes the worst symptoms of the reaction is called histamine. The most common symptoms are itchy and watery eyes, sneezing, an itchy and runny nose, rashes, fatigue, and hives. This early phase of reaction begins within the first few minutes of exposure and is due to the chemicals like histamine released during this phase. Most over-the-counter allergy medications will block histamine from binding to its receptor and therefore prevent the symptoms from appearing, but the allergic reaction (ie the immune response, antibody production and mast cell chemical release) has still taken place. The body has still mounted a response to the cat or pollen or dust, but we just don't suffer symptoms. The late phase reaction is caused by the other inflammatory cells that have been recruited into the area and may start two to four hours after initial exposure, leading to inflammation, swelling and congestion.
The IgE antibodies do not stay in the blood long enough for us to reliably measure in order to test for allergies. Therefore exposure to the allergen is typically required in allergy testing in the form of a skin scratch test. This is done in a physician's office. Some Naturopathic Doctors (NDs) like myself, Dr. Nicole Shortt, can perform an allergy test (skin scratch method) in office for weeds, trees, grasses, ragweed, mold, dogs, cats and dust mites. Additional allergens can be measured in an allergy specialist's (a Medical Doctor specializing in allergies) office and this process requires a referral from your family physician. The test involves a gentle scratch of the skin with the allergen and it takes about 30 minutes to administer the test and read the results. If you are allergic to the allergen (pollen, food or pet), the release of histamine will cause a local swelling and red area called a wheal. This is a scientific test that directly measures whether your body is producing this type of allergy (remember this is called a Type I immediate hypersensitivity with IgE antibodies).
Other types of immune-mediated reactions to allergens include Type III hypersensitivity reactions producing IgG antibodies. This is a delayed type and is not considered a true allergy, but it is often referred to as a sensitivity or intolerance. The IgG antibodies are produced in an overreaction against proteins in certains foods, and remain in the blood for 23-96 days. These circulating IgG antibodies will form complexes with the proteins they have been trained to recognize (the antigen) and form antibody-antigen complexes. Remember, the antigen is a piece from the offending allergen (the substance that we know as a food – like cheese, for example). These circulating immune complexes can deposit in the tissue, release inflammatory chemicals and cause tissue damage. Symptoms associated with an IgG food reaction include fatigue, weakness, reduced tolerance for exertion, eczema, psoriasis, other rashes, food-induced bronchitis and asthma, abdominal pain, bloating, nausea, diarrhea, disordered thinking, memory and behavioral problems, as well as musculoskeletal pain, swelling and stiffness. This list appears long and is consistent with what I have seen in clinical practice after using this test regularly for several years. In addition to the symptom association with IgG levels detected in the blood, there is a growing body of evidence showing clinical benefit of IgG testing in irritable bowel syndrome (IBS), Crohn's disease, dyspepsia, migraine headaches and obesity. Click here for more information on this type of testing. It is done in office and it takes only a few minutes to take the blood sample. The blood is taken from a finger prick, like you would do for a blood sugar test if you were diabetic, and is then sent to a laboratory for testing.
Now that you are up to speed on the allergic process and testing it makes the explanation of treatment choices much easier to understand.
Click the following link to read the next article in this series: Natural Allergy Treatment Options