Allergen specific IgE antibodies (s-IgE) to 6 inhaled allergens in the sera of 49 patients with allergic rhinitis were measured using AlaSTAT and CAP RAST. The results of the two methods were then compared.
The s-IgE values obtained using AlaSTAT were higher than those obtained using CAP RAST. The positive and negative agreement for CAP RAST compared to AlaSTAT was 87.0% and 91.7%, respectively.
The s-IgE levels of the standards in the AlaSTAT kit were measured using CAP RAST and found to be lower than the s-IgE levels marked on the labels of the standards. Thus, the higher AlaSTAT values were due to the low concentration of the AlaSTAT s-IgE standards.
Nine out of 18 CAP negative/AlaSTAT positive (C-/A+) results were obtained for cat allergens-IgE. A RAST inhibition test was therefore performed on the C-/A+sera using AlaSTAT, with cat allergens and house dust mite extract as an inhibitor. The house dust mite extract was completely inhibited by the responses in the sera to the AlaSTAT cat allergens, but not by the cat allergen extract. These results suggest that the house dust mite allergen was contaminated with cat allergen in the AlaSTAT system.
The responses of all sera with CAP positive/AlaSTAT negative (C+/A-) results were inhibited by the addition of the corresponding allergens to the solid phase allergen.
These results suggest that the discrepancy in the results between these two s-IgE measurement kits was due to the calibration of standards and the quality of the allergen extracts and allergen raw materials used in the AlaSTAT kit.
Our findings emphasize the need for standardized references and allergens in commercial s-IgE measurement kits.
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