Allergic diseases
In 1902, two French scientists injected dogs with a small amount of extract from the sea anemone. Nothing happened. A week later, they repeated the procedure in exactly the same way – and watched, amazed, as the animals developed a severe reaction.
The dogs had somehow become sensitive to the formerly harmless substance. The researchers had discovered allergy.
In the decades since that landmark series of experiments, scientists have come to know a great deal more about the phenomenon called allergy. Researchers have found that, ironically, allergy results from a malfunction of the immune system, a collection of cells and molecules that exists to protect us from harm.
Normally, the body learns to defend itself through experience – by encountering, battling and remembering one enemy after another. For decades, medical science has taken advantage of this process by using vaccinations to create protective immunity. Vaccination “teaches” the immune system to “remember” a disease.
Allergic reactions occur when the immune system mistakenly identifies innocent foreign substances as potentially harmful. Such substances are called allergens. Pollens, mold spores, house dust mites, animal dander and foods are among the allergens that most frequently cause allergic symptoms.
Antibodies are an integral part of the immune system and therefore play a central role in the development of allergic symptoms. Immunoglobulin E (IgE), or the allergic antibody, plays a key role in the most common type of allergic reactions. Without IgE, the immunologic response to an allergen can not occur.
