The common symptoms of allergies may be generated by a defense the body developed to fight off parasites.

Seasonal allergy sufferers can probably blame parasites -- not grasses, weeds and trees -- for their sinus woes.

The plants' harmless pollen enzymes confuse the immune system into triggering the runny nose and watery eyes chain reaction, but humans might have initially developed that defense to fight off parasites.

THE GIST:

• Allergies are the product of an immune system misstep.

• The immune system reacts similarly to allergens and parasites.

• Genes and the environment are largely to blame for why some people develop allergies.

Pollen from plants like this goldenrod confuse the immune system into triggering the runny nose and watery eyes reaction, a response originally developed to fight off parasites.

Getty Images

"So the idea is that the protease allergens (protein-splitting enzymes) cleave the same sensor proteins that evolved to detect proteases produced by the parasitic worms," said Ruslan Medzhitov, an immunobiologist at Yale University. "Thus the same response is induced unintentionally, and this may explain why this class of allergens has allergenic activity."

Understanding exactly how allergies work has also eluded scientists, since the immune system reacts differently to allergens than other foreign substances. Only recently have Medzhitov and colleagues identified a type of white blood cells called basophils as being responsible for many allergic responses.

For instance, when the immune system mistakenly tags ragweed pollen as a parasitic invader, basophils alert the immune system to secrete the specialized antibody immunoglobulin E (IgE). That triggers the release of histamines, or chemicals released by cells of the immune system during the inflammatory response. That, in turn, causes those annoying symptoms of allergies.

"The point about allergies is that you respond with a class of antibodies called IgE whose function remains unknown," said Marshall Plaut, chief of the allergic mechanisms section at the National Institutes of Allergy and Infectious Diseases.

It takes repeated allergen exposure over time to build up a strong IgE immune response and reduced symptoms, which is why seasonal allergies can seemingly strike out of nowhere.

It's trickier to explain why around 40 percent of the population is allergy prone and the rest isn't.

"The primary reason is probably genetic, and I say 'probably' because we don't have absolute evidence for it," Plaut said, adding that scientists haven't identified the specific genes responsible for allergic diseases.

Children may therefore inherit seasonal allergies from their parents, but it doesn't all boil down to DNA.

"You can't really separate genetics and environment the same way people used to do 30 or 40 years ago because we know they're very interactive, and we know that certain environmental factors can influence genetic factors," Plaut said.

Early childhood exposure to pets, pollutants and specific allergens are among the major allergy co-factors.

Though allergies might seem like nothing to sneeze about, scientists still have many questions to answer about why the immune system hiccup happens and how to prevent it.

"This is one of the big puzzles in immunology, and the answer isn't completely known," Medzhitov said.

By Cristen Conger – Discovery News

Allergies cause some of us to react to our environment in ways that cause discomfort and miserable suffering. If you or someone you love suffers from any kind of allergy symptoms, take the next step! Reserve your Comprehensive Allergy Assessment. Help us help you eliminate these allergy symptoms and become allergy-free, once and for all!

In addition, virtually every allergy sufferer has gastro-intestinal challenges! With over 60% of your immune system located in your intestines, it is believed that most allergy symptoms may be due to an intestinal challenge and not a true-allergy-weakness or predisposition! A Comprehensive Digestive Stool Analysis may be your ticket to better health and fewer allergies! This test will help us uncover the hidden challenges in your gut that are making your life difficult to cope with.

Most health insurance benefits include these diagnostic procedures. Call our HealthQuest Hotline at 1-800-794-1855 or our HealthQuest Clinic at 847-428-8850 for more information or to schedule an appointment.