Detection Rate of Allergen-Specific IgE by Multiple Antigen Simultaneous Test-Immunoblot Assay

Park, Do Sim; Cho, Ji Hyun; Lee, Key Earn; Ko, Sun; Kim, Hak Ryul; Choi, Sam Im; Lee, Young Jin

Abstract

BACKGROUND
A new multiple antigen simultaneous test (MAST) has recently been introduced that is simple, rapid, and economical, and requires a small amount of serum samples. We evaluated the MAST-immunoblot assay (AllergyScreen; R-Biopharm, Darmstadt, Germany) for its specific antigen detection rate, and the results were interpreted based on the cut-off levels of classes 0.5, 1.0, 2.0, and 3.0 and correlated with clinical information. METHODS: A total of 166 allergic patients were tested by AllergyScreen (AS) for 10 specific allergens and the results were compared with skin prick test (SPT, cut-off=2+) or specific IgE (cut-off=class 1) on Uni-CAP system (uCAP). Thirty-five healthy subjects considered as truly negative for all allergens were also tested by AS to get the best cut-off level using the receiver operating characteristics (ROC) curve analysis and to evaluate its clinical specificity. RESULTS: The sensitivities (AS/uCAP, 73-31% and AS/SPT, 27-63%), specificities (AS/uCAP, 89-100% and AS/SP, 81-97%), and agreements (AS/uCAP 71-82% and AS/SPT 77-80%) varied with the cut-offm levels used and allergens tested. The overall linear regression equation was Y=0.69X+0.10, R=0.81 (P<0.0001). The best cut off level was >0.5 class and efficiency was 82% (AS/uCAP) and 75% (AS/ SPT). However, 25 (71%) of the healthy subjects showed positive reactions (0.6-4.0 class) to at least one allergen. CONCLUSIONS: Using an appropriate cut-off, AS/uCAP showed the sensitivity, specificity, and agreement at an acceptable level, and similar or better results compared with previous reports on MAST/ SPT. The AS can be an efficient way of testing for specific allergens in the clinical laboratory or at the physician's office. But, in view of the positive reactions in the healthy subjects, a class of less than 4.0 on AS must be integrated with clinical information for an appropriate data interpretation.