The first time a person with a predisposition to develop allergies is exposed to an allergen, say dust mites, his immune system develops "special white blood cells (T-cells)" that "recognize the allergen as foreign and release chemicals in response.  These chemicals travel through the blood and instruct another kind of white blood cell (B-Cells) to produce IgE antibodies," according to NationalJewish.org.

"Some of these antibodies attach to the outside of another special type of white blood cell called a mast cell.  Mast cells are scattered throughout the skin and respiratory tract and their purpose is to help mediate the inflammatory response of the immune system.  IgE antibodies can remain attached to mast cells for many years."

Now your body is sensitized.  That means it's ready for battle if you're ever exposed to dust mites again.  This response is good if the invader is a bad parasite, bacteria or virus.  But an allergy is a defense against allergens, things that are harmless to 90 percent of people.

Once your body is sensitized to an allergen, say dust mites, all subsequent exposures will result in an allergic response or allergic reaction.  When you inhale the dust mite it will attach itself immediately to a dust mite IgE, and cause the mast cell to release the mediators of infammation. 

These mediators are histamine, leukotrienes, and cytokines.  NJH describes them as chemicals that act as "special messengers" that allows "immune cells to talk to each other."  

The most common mediator is histamine.  NJH states that "Histamine opens small blood vessels causing them to leak fluid.  This results in inflammation: warming and swelling of the skin, itching and watery eyes.  Histamine causes sneezing and increased mucus production in the nasal cavity and airways that lead to runny nose, post nasal drip, and cough."

Another mediator is leukotriene, which causes inflammation of the muscles lining your air passages.  If you have asthma your air passages are already somewhat inflamed, and the allergic response makes this worse and causes narrowed air passages, and thus your asthma attack. 

This is why it's especially important for most asthmatics to keep their asthma under control with inhaled corticosteroids, such as what are in Advair and Symbicort.  These medicines help minimize chronic airway inflammation so when you are exposed to allergens they don't irritate your asthma (as much).

Other options you can try are antihystamines like Claratin, leukotriene antagonists like Singulair, and IgE inhibitors like Xolair.And, of course, there's the old stanby therapy called "Allergen Avoidance."  

One or a combination of these options work for many allergic asthmatics, while others continue to struggle.  It seems despite all the improvements in asthma and allergy medicines, allergens continue to be a ubiquitous annoyance. 

What do you think?