Performance evaluation of a specific IgE assay developed for the ADVIA centaurR immunoassay system Anita Birgit Petersen a, * , Pernille Gudmann b , Pernille Milvang-Grbnager b , Rikke Mbrkeberg b , Sbren Bbgestrand b , Allan Linneberg c , Niels Johansen a a In Vitro Diagnostics Business Unit, ALK-Abello ´, Denmark b Analytical R&D, ALK-Abello ´, Denmark c Research Centre for Prevention and Health, Glostrup University Hospital, Denmark Received 22 March 2004; received in revised form 11 June 2004; accepted 23 June 2004 Available online 4 August 2004 Abstract Objective: To develop and evaluate a liquid phase immunoassay for accurate determination of allergen-specific IgE (sIgE) as a useful tool in the diagnosis of allergy patients. Design and methods: A fully automated, quantitative sIgE assay was developed for the ADVIA Centaur technology platform using a unique calibration method based on a recombinant reference allergen. Compared to most other IgE-assays, the assay employs a reverse sandwich architecture using monoclonal mouse anti-human IgE antibody covalently bound to paramagnetic particles in the solid phase and capturing the sample IgE. Bound sIgE reacts with liquid biotin-labeled allergen, which is detected as chemiluminescence using acridiniumester-labeled streptavidin. Results: The ADVIA Centaur sIgE assay (Centaur assay) has exclusive reactivity to human IgE and performs with excellent linearity in the assay range 0.35–100 kU/L and high precision (imprecision within-run b2.6%, between-run b4.9%, and total imprecision b7.1%). The analytical sensitivity is b0.10 kU/L. Using Pharmacia CAP system FEIA (CAP) as a comparative method, positive/negative concordance was 94% at 0.35 kU/L cut-off, and the Centaur assay has a sensitivity of 90% and a specificity of 98%. Validation of the assay in a general population sample (The Copenhagen allergy study) revealed that sIgE was highly associated with a clinical diagnosis of inhalation allergy. Conclusions: The Centaur assay is an allergen-specific assay for measurement of IgE without interference from other types of immunoglobulins or nonspecific IgE. The assay performs with a linear reaction, high assay range, and good reproducibility. The assay correlates well with the CAP system and is in agreement with clinical diagnosis. D 2004 The Canadian Society of Clinical Chemists. All rights reserved. Keywords: Specific IgE; Immunoassay; Allergen; Biotin; ADVIA Centaur Introduction Most type I allergies are triggered by one or more allergens which are antigens that trigger an IgE-mediated allergic reaction [1]. Sources of allergens are house dust mites and their waste; hair, dander, and saliva of animals; pollens from tree, grass, and weed; mould spores; venom of stinging insects; latex; or drugs such as h-lactams. IgE antibody production is a central feature of the allergic diseases. These include allergic rhinitis, asthma, food allergy, stinging insect allergy, latex allergy, and drug allergy. The expression of an allergic disease requires several sequential events, including 0009-9120/$ - see front matter D 2004 The Canadian Society of Clinical Chemists. All rights reserved. doi:10.1016/j.clinbiochem.2004.06.010 Abbreviations: sIgE, specific IgE; Centaur, ADVIA Centaur-specific IgE; CAP, Pharmacia CAP system FEIA; SPT, skin prick test; d1, House dust mite (Dermatophagoides pteronyssinus); d2, House dust mite (Dermatophagoides farinae); e1, Cat dander (Felix domesticus); f1, Egg white; f2, Cow’s milk; g6, Timothy grass (Phleum pratense); i1, Bee venom (Apis mellifera); i3, Yellow jacket venom (Vespula spp.); m6, Alternaria (Alternaria alternata); t3, Birch (Betula verrucosa); t9, Olive (Olea europaea); w6, Mugwort (Artemisia vulgaris); w19, Wall pellitory (Parietaria officinalis); Bet v 1, silver birch major allergen; RLU, Relative light unit(s); BCF, background calibration factor; SCF, slope calibration factor; NSB, nonspecific background; MDD, minimum detectable dose; SEM, standard error of the mean. * Corresponding author. ALK-Abello ´, In Vitro Diagnostics Business Unit, Gymnasievej 5, DK-3660 Stenloese, Denmark. Fax: +45 4574 7887. E-mail address: AIP@dk.alk-abello.com (A.B. Petersen). Clinical Biochemistry 37 (2004) 882 – 892