Allergies and your immune system

Allergies may affect up to 40 million people in the United States every year. The manifestations of allergies range from annoying symptoms of a runny nose and sneezing to life threatening obstruction of breathing. Many people may only have allergy symptoms for a few weeks out of the year, while others are bothered by repeated sinus infections or asthma. For the pilot, there are effective treatments for almost the entire spectrum of allergic symptoms that will not ground the pilot, or are easily waiverable after proper reporting.

Terminology

The most common manifestations of allergies is the runny nose (rhinitis), sneezing and itching eyes. These symptoms may be seasonal when certain grasses, flowers, trees or molds shed pollen or spores (Seasonal Allergic Rhinitis or SAR). Some individuals are plagued with these symptoms nearly continuously regardless of the season (Perennial Allergic Rhinitis). These people may be sensitive to dust, animal dander or other common materials. Non-allergic rhinitis, also known as vasomotor rhinitis or irritant rhinitis, may be caused by smoke, fumes, odors, chemicals or other unknown sources, may cause symptoms year-round. Common colds, caused by rhino viruses, may have similar symptoms of congestion and runny nose, but are not usually associated with itching eyes. Colds usually resolve within five to ten days and do not occur regularly with a particular season.

Immune system and allergic responses

Allergies are caused by the body’s reaction to outside proteins or particles (allergens). The immune system releases chemicals from certain blood cells and tissues called histamines that cause a reaction to the allergens. Generally, the mucus membranes near the site where the allergen reaches the body react by swelling and leaking clear fluid. The tissue is also irritated giving a scratching, itching sensation.

There are a variety of methods for testing for allergies. They include skin tests such as patch testing, intradermal testing and scratch/prick testing. Blood testing is used to look for evidence of allergies in the body. A complete description of each type of testing is found in the August 15, 2002 issue of American Family Physician in Allergy Testing. There is also a Patient information handout: "Allergy Testing" If the sinus passages are constantly swollen and filled with fluid, an excellent culture site is created for bacteria in the respiratory tract. Sinusitis, ear blocks and sinus blocks may result, particularly with repeated changes in atmospheric pressure. In more severe cases, the histamines and other chemicals released by the body may act not only on the local site of exposure, but on the entire body. The result may be an asthma attack as the breathing airways swell, leak fluid and close down. Allergies can also cause itching over the entire body.