|
Accurate results with ImmunoCAP® when you need to know for sure
Detection of allergen specific IgE antibodies is essential in the assessment of a patient with allergy like symptoms. Recent studies have also demonstrated that the quantitative level of allergen specific IgE antibodies provides significant information as to whether an IgE sensitized individual is likely to be clinically allergic. To enable the best care of the patient it is therefore essential that allergen specific IgE antibodies results are quantitatively and correctly determined. Reproducibility and absence of bias are two key performance characteristics for an immunoassay. |
Fig. 1
|
Assays for allergen specific IgE antibodies have so far been evaluated mainly for precision, not for accuracy, due to lack of independent analytical methods. However, with the introduction of allergen specific human-mouse chimeric IgE antibodies (fig.1) there are now tools available for preparation of samples in which the IgE antibody content can be accurately determined by use of amino acid analysis, an independent method for measuring protein concentration. The same sample can then be analyzed using routine assays based on immunoassay technology, measuring the IgE molecule both as allergen specific antibody (sIgE) and as total IgE (tIgE). In a recent publication by Wood and co-workers (1), this approach was used for the first time to evaluate the accuracy of three different immunoassays for specific IgE, ImmunoCAP from Phadia (Uppsala, Sweden), Immulite 2000 from Siemens Medical Solutions Diagnostics (Tarrytown, NY) and Turbo RAST from Hycor Biomedical (Garden Grove, CA). |
| Using samples containing chimeric IgE antibody of known concentrations, the three systems give fairly similar total IgE results. The specific IgE results, however, differ significantly. ImmunoCAP specific IgE shows excellent agreement with total IgE, Immulite is considerably overestimating and Hycor underestimating specific IgE concentrations, indicating a lack of accuracy for the latter two tests (fig.2). |
| As each of the samples analysed is pure and contains only one species of antibody, total and specific IgE assays should give the same result and be in agreement with the known amount added. Nevertheless, two out of the three systems give discrepant results. As the authors point out the clinical implications of these findings could be serious: “These findings have potentially serious clinical implications since each of these systems is widely used. It is therefore important that all laboratories clarify which system they are using. Just because 2 systems present their results in the same units, does not mean that the results are necessarily correct or interchangeable.” (1) |
 Fig. 2. Adapted from reference 1 |
| 1. Wood R, Segall N, Ahlstedt S, Williams B. Accuracy of IgE antibody laboratory results. Annals of Allergy, Asthma and Immunology 2007;99:34-41. |
|
|
 |
Copyright © 2004-2008 - Rue des Palais 100, B-1030 Brussels - Belgium Tel.: +32(0)2/240.26.11 CLI and Pan Global Media are not responsible for any error or omission that could take place in the electronic display of product or company data. |