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Λεξικό .. Serologic tests for allergy diagnosis

Serologic tests for allergy diagnosis, Ορολογικές δοκιμασίες διάγνωσης αλλεργίας. All immunoassays for allergen-specific IgE make use of the fact that the analyte (i.e. the allergen-specific IgE) has a dual specificity: it reacts  1. with allergen and 2. with anti-IgE.

Basic principles:The basic assay principle is usually to attach a different label to each of the two reagents and to score the amount of reaction product containing both labels. One label is commonly a sizeable particle and the other label is a tag that can be detected by the radiation-emitting or radiation-absorbing capacities of either the tag itself or of products attached to (or produced via) the tag. The first reagent will be called the catching reagent, the second reagent: the detecting reagent. Both catching and detection can be performed in an indirect way, e.g. via (strept) avidin-binding of biotinylated reagent. In the tests currently available two incubation steps, each followed by a washing step, are usually required. In the first incubation the analyte is extracted (=caught) from the test sample and in the second incubation the extracted analytic is combined with the labeled reagent. The first washing step is usually required to avoid an interfering reaction between substances in the test sample and the labelled reagent: in the case of labelled anti-IgE the interfering substance is non-allergen-specific IgE; in the case of labelled allergen the interfering substance is allergen-specific IgG/IgA. In principle this first washing step can be avoided if a large enough excess of labelled reagent can be used, but this is usually impractical. The second washing step is required to remove the excess of the labelled reagent. This second washing step can be avoided by using a proximity label, i.e. a tag that will be detected only in combination with the other label (e.g. the solid phase) and not alone (i.e. in free solution).

Catching with anti-IgE, detection with allergen: The simplest version of this procedure is to incubate the sample with solid-phase anti-IgE followed by an incubation with labelled allergen. This procedure is particularly suitable to compare absolute levels and affinities of IgE and IgG(4) antibodies. Its sensitivity is usually less than the reversed procedure discussed below. Catching with allergen, detection with anti-IgE: The RAST is of course the best studied example of this type of test. Catching (extraction) of allergen-specific IgE by solid-phase allergen can be improved by using a modification of the RAST procedure. In this modified RAST procedure the allergen reacts in homogeneous solution with the IgE antibodies followed by absorption to a solid phase either via solid-phase coupled allergen-specific (monoclonal) antibodies or via a solid-phase coupled reagent that binds to a tag attached to the allergen. Alternative reagents will be discussed that sometimes prove to be effective in catching allergen from solution, e.g. solid-phase coupled poly-proline, which binds the crossreactive allergen profiline, and solid-phase coupled enzyme inhibitors, e.g. benzamidine, which binds a variety of allergenic proteolytic enzymes.


Aalberse, R.C., et al: New serologic tests in allergy diagnosis. In: New Diagnostic Tests in Allergy. Symposium 7. In the Annual Meeting of the EAACI, Zűrich, Switzerland, May 25-29, 1991.

Γκέλης Ν.Δ. - Λεξικό Αλλεργίας - Εκδόσεις ΒΕΛΛΕΡOΦΟΝΤΗΣ - Κόρινθος 2013

Gelis Ν.D. - Dictionary of Allergies - VELLEROFONTIS Publications - Corinth 2013