AB1552 PERFORMANCE OF A SOLID-PHASE PHOTOMETRIC SINGLE USE IMMUNOASSAY MICROARRAY PROTOTYPE IN THE DETECTION OF IGG ANTIBODIES AGAINST CENTROMERE PROTEIN B (CENP-B) IN HUMAN SERUM

Abstract

BackgroundSystemic Sclerosis (SSc) is a chronic multisystem autoimmune (AI) disease, characterized by progressive fibrosis of the skin and internal organs and vascular injury.[1]Biomarker testing plays an important part in disease classification, identification of sub-sets of SSc (e.g., CREST/ Limited SSc), prognosis and progression. Presence of antibodies against centromere proteins (CENP) weighs 3 points in the ACR/EULAR Classification Criteria.[2]Development of highly automated diagnostic tools remains a clinical need.ObjectivesTo evaluate the performance of a solid-phase photometric single use immunoassay microarray prototype for thein vitroqualitative detection of IgG antibodies against Extractable Nuclear Antigens (ENA) of CENP-B in human serum when tested using the MosaiQTMSystem.MethodsMosaiQ CENP-B microarray prototypes (Quotient Suisse, Eysins, CH) were prepared by printing CENP-B antigens in duplicate onto Epoxy-silane glass chips, followed by a blocking and preservative step. Microarrays consisting of 2 separate sides were assembled into Magazines (containing 250 microarrays) for processing on the MosaiQ 125 instrument. Human serum samples/buffers/reagents are loaded on the instrument and automatically the microarrays undergo sample/buffer/reagent addition to generate antigen spot signals which are read and interpreted by the instrument using a proprietary algorithm. A cohort of 26 serum samples reactive for anti-CENP-B antibodies (as defined by testing with 2 commercial assays) and 25 non-reactive serum samples from Swiss Red Cross blood donations were tested in duplicate.Results25 out of 26 CENP-B antibody reactive samples were determined reactive by the MosaiQ CENP-B microarray prototype. The only discordant sample was reactive in one of the reference methods and non-reactive in the other, suggesting the potential for a false reactive by one of the reference methods. All 26 non-reactive samples were determined non-reactive by the prototype assay. Derived sensitivity (including presumptive false non-reactive) is 0.96 (95%CI 0.87 – 0.99) and specificity is 1.0 (95%CI 0.93 – 1.0).ConclusionThese preliminary results support the performance of the investigational microarray prototype for the detection of CENP-B antibodies in human serum using the MosaiQ System. Clinical studies to confirm these observations are ongoing. Additionally, the microarray has the potential to print up to 66 spots per side, allowing for the capability to generate large multiplex panels for the detection and characterization of AI diseases.