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A New Diagnostic Test
The
treatment of allergies is based on making the body insensitive to the
allergens. In other words, the patient is gradually accustomed to higher
and higher doses of the substance. But before this can happen, it is
important to know exactly what the body is reacting to. At the moment,
this is usually determined using the prick test in which potential allergens
are applied to the patient's skin. It is then a matter of waiting to
see if the skin reacts. The problem with the prick test is that it often
produces false-positive results. This is because the body will react
to certain substances even if no allergy exists.
But the test is also controversial for other reasons. Firstly, it can be very unpleasant. Secondly, the result is dependent on the purity of the allergens applied, the patient's sensitivity to plasters or preservatives and the way in which the skin is stimulated. It also depends on the doctor's experience, of course.
The outlook seems bright for new laboratory methods in the shape of blood tests developed by Bayer's Diagnostics Business Group. With these tests, it is now possible to screen specifically for the presence of, distinguish between and identify IgE antibodies in the blood of allergy sufferers. Because antibodies differ structurally depending on the allergens in response to which they were formed, they can be identified and classified individually. This means that we can pinpoint exactly the substances to which the sufferer is allergic. What's more, this method provides quantitative information about IgE antibodies for the first time. A precise diagnosis can be provided by the ADVIA® Centaur Allergy laboratory system. It uses defined allergens to screen for the presence of any class E immunoglobulins in the blood which are directed specifically against these allergens. At present, the device can test for 140 individual allergens, and this figure is set to rise to 300 in the foreseeable future. More good news: only 35 microliters of blood (1 microliter = a millionth of a liter) are needed for the test. And the results are ready in just half an hour.
A reassuring prospect for the allergy sufferer. Because even though the ADVIA® Centaur cannot eliminate allergies, it can point us reliably in the direction of a cure and considerably shorten the process as well.
And it may even help Maria K. Although she has her weeping fig allergy under control, her eye has started to feel itchy again recently from time to time. She thinks that it happens "whenever I have been eating nuts." But she is not quite sure”.
ADVIA® Centaur Allergy
For the allergy test, the blood sample in the device is exposed to a large number of allergens (140 at present). Whenever the patient's blood contains an IgE antibody for a particular allergen, these antibody molecules become attached to the allergens in a lock-and-key arrangement. The complexes formed in this way can then be visualized by means of chemical luminescence and so be determined and measured. The ADVIA® Centaur is used in clinical laboratories for many applications, but a normal doctor's office will not usually have a device of this type. |
The
ADVIA® Centaur is an established device developed by Bayer's
Diagnostics Business Group. It is used to determine various values
relating to blood components. The "Allergy" version
of the ADVIA Centaur is designed to perform allergy tests too.(Source: Revista Report 1/2002. Author: Ralf Daute)
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