Word: pollens
(lookup in dictionary)
(lookup stats)
Dates: during 1990-1999
Sort By: most recent first
(reverse)
Those allergic to pollen are only the most numerous group in a much broader class of people who react badly to invisible tormentors usually in the air. In a sense, hay fever sufferers are among the lucky ones, since they have at least some idea of what is bothering them, how to minimize the problem and when it will stop. Millions of others are vulnerable all year round and unexpectedly come down with a dismaying variety of symptoms. They swell up, - break out in hives and blisters, develop eczema or upset stomachs, and have breathing difficulties. After the initial reaction...
Allergies, like autoimmune diseases such as arthritis and lupus, result from aberrant functioning of the human immune system, the body's remarkable defense against dangerous invaders, including viruses, bacteria and parasites. In the case of hay fever, the immune system perceives the fuzzy grain of pollen as a threat. The cause of the confusion, explains botanist Walter Lewis of Washington University in St. Louis, is a chemical message encoded by proteins in the pollen grain's cell wall...
...next time similar pollen grains are detected, the antibodies signal the mast cells, which release a flood of chemicals, including histamine, against the harmless intruder. It is histamine that causes swelling, itching and other irritations all too familiar to hay fever sufferers. At the same time, additional IgE antibodies are produced and placed in position on mast cells, so that the next exposure to the pollen may produce a more severe response...
Another type of immune cell that swings into action at the first hint of pollen produces a substance that is toxic to parasitic worms. "Probably the IgE response is there primarily to protect people against parasites," says Dr. Harold Nelson of the National Jewish Center for Immunology and Respiratory Medicine in Denver. Its response to pollen, he says, is simply a mistake...
...While pollen is the No. 1 troublemaker for allergy sufferers, hundreds of other substances can provoke the immune system into an irrational IgE response. Among the more formidable and difficult to avoid are the droppings of the dust mite, a microscopic insect that thrives by the millions wherever dust collects in a house. Living on sloughed-off flecks of human skin (dander) and other unappetizing protein, it leaves droppings that are about the size of pollen grains -- and just as easy to inhale. Mite dung, unfortunately, is an allergen that produces the familiar sneezing, coughing, itching symptoms in half...