Asthma - Antibody Tests

Allergy antibodies are members of the group of IgE antibodies. In this group can be found antibodies against the protein of trees and grasses, against animal hair and other inhaled substances, and against foods. Blood tests for IgE antibodies against plants and animals are very reliable, very helpful in diagnosing allergies. Testing for food antibodies is less satisfactory than testing for antibodies to the inhaled substances.

The technology used for determining these allergy antibodies is called RAST testing. Using RAST, it is possible to look for antibodies that react to allergy-causing substances. RAST can also be used to follow the progress of an allergic disease. As the condition lessens, the antibodies diminish, too. Tests for many allergy-causing substances (allergens) can be done on a single, small specimen of blood. This makes blood testing quicker and easier than skin testing, the traditional method of finding IgE antibodies. Skin testing is still the usual method of finding antibodies, however, because it detects smaller amounts of antibodies than RAST testing and is less expensive.

Testing of any type is best done on an individualized basis, the tests selected to correspond to information obtained from the medical history. There is no need to test for grass pollen in a patient whose symptoms are exclusively in the winter, no purpose to testing for foods such as lobster that the patient never eats. In any case, although the history is most significant in evaluation of an allergic patient, many tests are available to establish the diagnosis and observe progress with treatment.