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Food allergies, hay fever, skin allergies, and reactions to pet dander: the symptoms of these allergies are different but the cause is the same. Your immune system is overreacting to an ordinarily harmless substance. Whether you get skin rashes, itchy eyes, wheezy airways, or a runny nose, an allergic response is no fun, and is sometimes dangerous. With that said, it’s good to know that the science of allergy treatment has come a long way. Doctors now understand the allergic response on a molecular level, producing better ways to diagnose and treat all kinds of allergies, from hay fever to food reactions. Learn to identify your allergic symptoms, pinpoint your triggers, distinguish between intolerance and allergy, and choose the best treatment for your particular type of allergy.
Prepared by the editors of Harvard Health Publications in consultation with John J. Costa, M.D., Assistant Clinical Professor of Medicine, Harvard Medical School, and Medical Director for Allergy & Clinical Immunology, Brigham & Women’s Hospital. 44 pages. (2009)
If you’ve never been stung by a bee, the first time will cause pain but won’t cause an allergic reaction. For many people, however, that first sting causes the immune system to arm itself against further bee venom attacks. If so, the next time you get stung, severe allergy symptoms may appear. Here’s how it works:
The first sting: A normal reaction includes pain and swelling at the site of the sting. In some people, certain immune cells called B plasma cells produce IgE antibodies against the bee venom. The IgE antibodies stick to immune cells called mast cells. This process, called sensitization, sets the stage for an allergic reaction the next time a bee stings.
The next sting: The IgE antibodies on the mast cells bind to the bee venom, prompting the mast cells to release substances that trigger allergic symptoms and inflammation, such as swift-acting histamine, slower-acting tryptase, prostaglandins, and leukotrienes.
Bee stings can cause allergic shock (anaphylaxis). This happens when mast cells are activated and two IgE antibodies bound by two neighboring IgE receptors are cross-linked (chemically connected) by an antigen, such as bee venom protein. Once the IgE antibodies are cross-linked, reactions can occur very quickly with even a very small amount of allergen.
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