title: Multisite analytical evaluation of the Abbott ARCHITECT cyclosporine assay.
abstract: The objective of this study was to evaluate the analytical performance of the Abbott ARCHITECT Cyclosporine (CsA) immunoassay in 7 clinical laboratories in comparison to liquid chromatography/tandem mass spectrometry (LC/MS/MS), Abbott TDx, Cobas Integra 800, and the Dade Dimension Xpand immunoassay. The ARCHITECT assay uses a whole blood specimen, a pretreatment step with organic reagents to precipitate proteins and extract the drug, followed by a 2-step automated immunoassay with magnetic microparticles coated with anti-CsA antibody and an acridinium-CsA tracer. Imprecision testing at the 7 evaluation sites gave a range of total % coefficient of variations of 7.5%-12.2% at 87.5 ng/mL, 6.6%-14.3% at 411 ng/mL, and 5.2%-10.7% at 916 ng/mL. The lower limit of quantification ranged from 12 to 20 ng/mL. Purified CsA metabolites AM1, AM1c, AM4N, AM9, and AM19 were tested in whole blood by the ARCHITECT assay and showed minimal cross-reactivity at all 7 sites. In particular, AM1 and AM9 cross-reactivity in the ARCHITECT assay, ranged from -2.5% to 0.2% and -0.8% to 2.2%, respectively, and was significantly lower than for the TDx assay, in which the values were 3.2% and 16.1%, respectively. Comparable testing of metabolites in the Dade Dimension Xpand assay at 2 evaluation sites showed cross-reactivity to AM4N (6.4% and 6.8%) and AM9 (2.6% and 3.6%) and testing on the Roche Integra 800 showed cross-reactivity to AM1c (2.4%), AM9 (10.7%), and AM19 (2.8%). Cyclosporine International Proficiency Testing Scheme samples, consisting of both pooled specimens from patients receiving CsA therapy as well as whole-blood specimens supplemented with CsA, were tested by the ARCHITECT assay at 6 sites and showed an average bias of -24 to -58 ng/mL versus LC/MSMS CsA and -2 to -37 ng/mL versus AxSYM CsA. Studies were performed with the ARCHITECT CsA assay on patient specimens with the following results: ARCHITECT CsA assay versus LC/MSMS, average bias of 31 ng/mL; ARCHITECT versus the Dade Dimension assay (4 sites), average biases of -7 to -228 ng/mL; ARCHITECT versus AxSYM and TDx, average biases of -4 and -53 ng/mL, respectively. Spearman correlation coefficients were >or=0.89. The ARCHITECT CsA assay has significantly reduced CsA metabolite interference relative to other immunoassays and is a convenient and sensitive semiautomated method to measure CsA in whole blood.
authors.affiliation: Université Catholique de Louvain, Cliniques Universitaires St. Luc, Brussels, Belgium. pierre.wallemacq@uclouvain.be
authors.forename: Pierre
authors.initials: P
authors.lastname: Wallemacq
authors.forename: Gregory T
authors.initials: GT
authors.lastname: Maine
authors.forename: Keith
authors.initials: K
authors.lastname: Berg
authors.forename: Thomas
authors.initials: T
authors.lastname: Rosiere
authors.forename: Pierre
authors.initials: P
authors.lastname: Marquet
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Aimo
authors.forename: Giulio
authors.initials: G
authors.lastname: Mengozzi
authors.forename: Julianna
authors.initials: J
authors.lastname: Young
authors.forename: Kurt
authors.initials: K
authors.lastname: Wonigeit
authors.forename: Robert
authors.initials: R
authors.lastname: Kretschmer
authors.forename: Bendicht
authors.initials: B
authors.lastname: Wermuth
authors.forename: Rainer W
authors.initials: RW
authors.lastname: Schmid
mesh_terms: D000918:Antibody Specificity; D002623:Chemistry Techniques, Analytical / Q000379:methods* / Q000592:standards*; D016572:Cyclosporine / Q000097:blood*; D004353:Drug Evaluation, Preclinical / Q000379:methods / Q000592:standards; D006801:Humans; D007118:Immunoassay / Q000379:methods / Q000592:standards
chemical_list: D016572:Cyclosporine