Scientists don't know why some people have a super sensitivity to allergens, but they do know the ways in which your body reacts to them. What you feel when an allergen comes in contact with you is a result of the chain reaction your body goes through to prevent an attack by a foreign substance. Those reactions cause the annoying symptoms we call allergies.
For example, your nose serves an important function for your lungs - it acts as a filter to clean the air you breathe. Nose hairs trap airborne substances, including allergens, preventing them from reaching your lungs. Small quantities of harmless substances, such as pollen, have no damaging effect on the lungs, meaning that the nose's filtration process works efficiently enough to insure that nothing has gotten through. Only when harmful substances are present should the nerves cause a dilation of the blood vessels inside the nose to block entry to foreign particles.
This system works fine with non-allergic individuals. But for people with allergies, the nose overdoes it and dilates the blood vessels unnecessarily. The result is the swelling, itching, and inflammation common to airborne allergic reactions. The truly unlucky allergy sufferers also experience excess fluid (mucus) release, to the delight of tissue manufacturers worldwide!
Similar symptoms are seen in the eyes. Your eyelids have the same job as your nose hairs in that they trap airborne substances such as allergens. Overly protective defense reactions cause your eyes to turn red and itchy, as well as to produce an overabundance of tears.
The Defense Mechanism
The best way to understand this mechanism is to first look at the label on your allergy medicine. There, you will see the word "antihistamine" as part of the drug's name. This is enough to tell you that your medicine has the ability to stop histamine (anti-histamine). But what is histamine? Where does it come from? And why does your medicine need to stop it?
Histamine is an inflammatory chemical that your body releases in the case of an allergic reaction. The release of histamine causes the dilation of capillaries, the contraction of smooth muscles (like the ones from your stomach and bladder), and the stimulation of gastric secretion. What gives your body the trigger to release such a chemical? The answer is your immune system.
The immune system protects your body against invading agents (like bacteria and viruses). In the case of allergies, your body reacts to a false alarm because airborne substances or other types of allergens are usually not harmful. The immune system of the allergic person mistakenly considers allergens to be an invading agent, and in response to the invasion tries to mobilize and attack. And that is why you take your medicine, to stop the release of histamine.
The agent of your body responsible for the attack is called Immunoglobulin E (Ig E). Ig E is an antibody (also a protein) that is released by your body in large amounts to battle the alleged invaders.
Your body is extremely complex. One of its capabilities is to store foreign agent information so that it can remember what invading agents look like. The body can then respond much faster in the case of a second attack by the same agent. Your body creates a huge library of different types of IgE just for you. The recognition is made because the structure of IgE and antigen are like a key fitting into a lock. So each key can only be used in one specific lock.
Where is the IgE protector found in the body? It is found attached to mast cells (tissue cells) and basophils (blood cells). When the allergen attaches to IgE it triggers a chain of reactions that, in the end, make the mast cells or basophils release histamine. It is this unecessary release of histamine that your medication (the anti-histamine) is designed to counteract.
This article was published by Pollen.com, copyright 2012. It can be accessed online at the following link.Allergic Rhinitis (Hay Fever)
Dust Mite Allergy
The Body's Reaction to Allergens