Just what is “allergy?”
Allergy is an over-reaction of the body’s immunologic or defense system. Our immunologic system uses multiple mechanisms to maintain our health and normally we pay little attention unless the defense responses become excessive. So allergy is not a disease, but is the body’s response to an attack by a foreign protein which has become excessive. Another name for allergy is hypersensitivity.
What are the main “offending proteins” which cause an allergic response?
Mostly we develop allergy symptoms (excessive immunologic responses) from foreign proteins that we breathe, that we eat or that come into contact with the skin. These offending proteins are called “allergens” and also “antigens.”
What are the most common antigens?
The respiratory or Inhalant Allergens that bother us most are dust and dust mites, pollens, animal danders, molds, plant fibers and various microscopic particles in the air that we breathe. Food allergy symptoms can be caused by most any food protein that we eat. Skin allergies are caused by a variety of animal and plant proteins and various other chemicals which are known as contact antigens. A common type is poison ivy and poison oak. Skin reactions can also be seen from inhaled and ingested antigens.
How does the body’s immunologic (defense) system fight off the foreign protein attacks?
There are many mechanisms and lots of complexities but generally the body releases a chemical called “histamine” which in turn evokes an inflammatory response. The inflammatory response is characterized by dilation and increased permeability of tiny blood vessels which in turn leads to swelling of tissues and increased secretions. That is why mosquito protein causes swelling at the bite site and why inhalant allergies cause nasal congestion, runny nose, postnasal drainage, sinus headaches, etc. Histamine also causes itching, sneezing, coughing, headaches and various other symptoms.
What is the importance of histamine in causing allergy symptoms?
Histamine causes a large proportion of the inflammatory response of tissues which we call allergy symptoms. There are other chemicals manufactured by the body, but histamine is the main culprit in causing symptoms such as itching, swelling, secretions et al.
How are allergy symptoms treated?
Most everyone knows to take antihistamines as a first line of defense to suppress allergy symptoms. Symptoms are relieved partially or completely when antihistamines block or slow the body’s histamine response. There are many different antihistamines widely available over-the-counter at pharmacies, groceries and other stores. Some antihistamines have the side effects of fatigue, drowsiness, a dazed feeling and other symptoms which can be more unpleasant than the allergy symptoms one is trying to relieve.
How does our immunologic system produce histamine?
Most histamine is produced by our “mast cells” and stored within these cells waiting for release into the surrounding tissues when a foreign protein attack occurs. The histamine is stored in granules within the mast cell. Mast cells are all over the body: in skin, in respiratory mucosa, in intestinal mucosa, in the brain and other organs and even circulating in the blood stream. If you have ever seen a blood smear under a microscope, you may recall the eosinophils which are large circulating mast cells that contain bright red-staining granules. Eosinophils are actually beautiful when magnified under the microscope but the bright red granules contain lots of histamine that can cause allergy symptom misery. People with allergies have an increased number of eosinophils in their blood.
What happens when our body is “attacked” by a foreign protein?
When the body’s immunologic system perceives the invasion of a foreign protein, it mobilizes various defense mechanisms. A primary response is the release of stored histamine from the mast cells. (That is why a mosquito bite itches and swells….. mast cells in the skin squirt out histamine in response to the foreign protein.) This is called the “Histamine Response” and is also what happens when we breathe or eat something to which we are allergic. In the respiratory tract we get itching (sneezing), congestion of nasal and sinus passages, runny nose and post-nasal drainage (excess secretions), coughing, headaches if sinus outflow passages are blocked, wheezing from bronchospasm if one has asthma, etc., etc., etc.
What measures can be used to treat allergies?
Avoidance of whatever is causing your symptoms is certainly important. By trial and error lots of people discover which antigen culprits affect them and try to stay away from them. Total avoidance is usually not possible as the microscopic particles can just be everywhere in the air we breathe. If one is allergic to some food that is more easily avoided. If one is sensitive to a pet, that is a more difficult problem.
What other medications are available besides antihistamines?
If excess secretions are a problem, decongestants can be helpful. Caution is advised if you have high blood pressure or heart problems. (Caution is also advised for using antihistamines if you have glaucoma or some urinary problems.) Various other medications are sometimes used for allergy sufferers.
What about steroids?
Corticosteroids are very powerful anti-inflammatory drugs and quite helpful for treating allergies and a host of other diseases. However they have significant side effects and are available only by prescription. Short term steroids are especially helpful for allergy flareups, for example poison ivy/oak, short seasonal exposures and the like. Your physician can provide further details if steroids are indicated.
What treatment is available when medications (Stage One Therapy) are not effective?
When allergy symptoms persist and are not helped effectively by medications the next step in treatment is immunotherapy. Immunotherapy involves testing (skin tests… more on that later) to determine which antigens (allergens) are causing the patient’s symptoms, then giving injections containing tiny amounts (parts per million) of those antigens which in turn cause the mast cells to release their stores of histamine. The patient thus obtains a “clear zone” which is a period of time when there is no effective histamine response from the mast cells to cause symptoms. It is a succession of these clear zones that provide relief from allergy symptoms.
