PB0304 - Evaluation of an automated FRET based ADAMTS-13 Activity Assay

Background: Thrombotic thrombocytopenia purpura (TTP) is a rare life-threatening disease resulting from an individual expressing severe deficiency in the activity of the von Willebrand factor (VWF) cleaving protease ADAMTS-13. Laboratory assessment of a patient's ADAMTS-13 activity levels is crucial in diagnosing TTP. Manual ELISA and FRET assays of ADAMTS13 activity levels are commonly used but are labour intensive and usually only available in specialist laboratories during core working hours. Recently an automated FRET based ADAMTS-13 activity assay has been brought onto the market which offers a less labour intensive testing method resulting in shorter turnaround times.

Aims: The Technofluor ADAMTS-13 Activity kit (Technoclone, Austria) was evaluated on the Ceveron s100 (Technoclone, Austria) analyser to determine its suitability for use.

Methods: 142 samples were tested with results compared to the Technoclone ELISA assay. Reproducibility was assessed with two levels of QC. Repeatability was assessed with 10 repeats of the same patient sample. 40 iTTP at presentation samples were included and 10 cTTP samples. Two pairs of pre and post TAK-755 (recombinant ADAMTS 13) were tested.

Results: ADAMTS-13 activity levels by ELISA had mean value of 23.4 IU/dL and by Ceveron were 28.3 IU/dL. The R value of the two groups was 0.96 and the R2 = 0.92. All 40 iTTP at presentation samples produced activity results of < 10 IU/dL on the Ceveron s100. Ceveron demonstrate reproducibility of a CV of 7.6% and repeatability of 8.4%, comparable to the ELISA repeatability is a CV of 8.7%. Results post TAK-755 had a mean of 87.4 IU/dL by ELISA and 107.4 IU/dL on the Ceveron.

Conclusion(s): The Technofluor ADAMTS-13 Activity kit on the Ceveron s100 analyser showed a strong correlation with results produced by the established ELISA method and was found to be a suitable alternative to the ELISA for the diagnosis and monitoring of iTTP and cTTP.