Meet The Expert

Meet the expert: Prof. Dr Ulrich Sack answers your questions on DxFLEX 13-Color Flow Cytometer

Beckman Coulter Life Sciences has introduced the DxFLEX, Europe’s first IVD, 13-colour clinical flow cytometry system at the Universität Leipzig, Medical Faculty, Institute of Clinical Immunology, Germany. In this webinar Prof. Ulrich Sack, MD will share his onboarding experience with DxFLEX and will demonstrate the advantages compared to traditional systems. The DxFLEX uses avalanche photodiode (APD) technology, which creates a highly sensitive semiconductor electronic device able to convert light to electricity. This addresses the limitations of traditional PMT–based flow cytometers. Prof. Sack states that the wide measuring range and the intuitive data processing enable a fast and easy introduction or modification of new measurement approaches. He considers the introduction of the device as a success.

When introducing DxFLEX into the lab, can I simply transfer my existing panel, or should I establish new panels?

When we introduced DxFLEX, we simply transferred our existing FACSCanto II protocols to the DxFLEX. Performance was very good, gating is easier. This is probably also true for Navios panels.

For extension of our panels, we have 3 strategies: 1) replacing antibodies in existing panels; 2) simply adding additional antibodies to existing panels, and 3) identifying BC panels (resp. Duraclones) and adding additional antibodies.

Can I easily transfer DxFLEX data into an Excel database?

Experimental data is automatically exported as a .CSV file through the statistics menu of the CytExpert for DxFLEX software.

Does DxFLEX require a specific interface for LIMS connectivity?

DxFLEX can transfer results to the LIMS system by exporting data as a .CSV file that can then be transferred to the LIMS by using a middleware solution.

Alternatively, Kaluza C can be used for analysis of data exported from CytExpert for DxFLEX and transfer of data to the LIMS.

How does the sensitivity of the DxFLEX compare to traditional flow cytometers which use photo-multiplier tubes (PMT)?

In our clinical study using the DuraClone B27 kit on FC500 and DxFLEX, there were a number of discordant results that were positive on DxFLEX but negative on FC500. These samples were retested using a lab developed test (LDT). In all cases, the DxFLEX results were proven to be true positives, hinting at a higher sensitivity of the DxFLEX in this case.

If I purchase the minimum DxFLEX configuration and then decide I need more channels, can the system be field upgraded at a later date?

The DxFLEX can be easily field upgraded by the Beckman Field Service Engineers with a simple exchange of the USB dongle to unlock additional functionality.

Is the CytExpert for DxFLEX software also IVD?

Yes, the CytExpert for DxFLEX software is part of the DxFLEX IVD system.

For QC tracking, does the instrument only track beads or does it track internal process controls as well?

The system currently only tracks the DxFLEX Daily QC Fluorospheres.

Is a 96-well plate loader available for the DxFLEX?

A plate loader* option is available as an add-on for the autoloader.

Can you please explain the APD technology in more detail?

Please check out our APD technology video for DxFLEX:

How do you deal with spillover? Is this frequent with this technology?

Compensation spillover will occur regardless of technology, however with the DxFLEX, due to the APD technology that features a linear gain response unlike conventional PMT-based cytometers, it is easy to set up compensation and automatically update the compensation library when changing gain settings.

Do you have experience with MRD-testing on the DxFLEX? Is the device fast enough to analyze 1—5x106 events?

The DxFLEX has an event rate of max. 30.000 events/s and should therefore be suitable for rare event analysis. Also, the limit of events per file is >25M when acquiring the maximum of 15 channels, so this does not limit in case of rare event analysis.

We are currently using Navios Ex, will it cause a lot of changes in our already established panels to DxFLEX?

In fact, we simply transferred our existing FACSCanto II protocols to the DxFLEX. This is probably also true for Navios panels, I guess. Performance was very good, gating is easier.

For extension of our panels, we have 3 strategies:

  1. Replacing antibodies in existing panels
  2. imply adding additional antibodies to existing panels
  3. Identifying BC panels (resp. Duraclones) and adding additional antibodies.

How is the data reproducibility in long run (e.g. ~6 months) and stability of the performance of APDs?

Based on our experience with the CytoFLEX* that the DxFLEX is based on, we do expect stable performance in the long run.

Is there volumetric counting available on the DxFLEX?

The volumetric counting option is available in the CytExpert for DxFLEX software but has not been validated. It is not for use in diagnostic procedures.

Is DxFLEX software 21 CFR Part 11 compliant?

Dr Carsten Lange: The CytExpert for DxFLEX software is currently not 21 CFR part 11 compliant. As this feature is needed primarily in a Biopharma setting, we encourage customers to use the CytoFLEX, which does feature 21 CFR part 11 compliant software, in such applications.

About Ulrich Sack

Professor Dr Ulrich Sack

Ulrich Sack is the head of the diagnostic laboratory of the Institute of Clinical Immunology, Medical Faculty, University of Leipzig, Germany. After his Medical study at Leipzig University and a fellowship of the Alexander von Humboldt Society at the Clinical Research Groups of the Max Planck Society in Erlangen, he completed his qualification in Clinical Immunology.

Since 2002 he has been holding a professorship at the Institute of Clinical Immunology, University of Leipzig, Germany. His main interest is translation of recent developments in immunology into clinical laboratories. Therefore, from 2008 to 2015 he supported the Translational Centre for Regenerative Medicine (TRM) at the University of Leipzig in the function of the Research Director. Furthermore, he was a group leader and advisor at the Fraunhofer Institute for Cell Therapy and Immunology from 2005 to 2015. He is involved in several networks of scientific experts in the field of clinical immunology and laboratory diagnostics.

As a technical assessor, he promotes ISO 15189, 17025, and 17043 accreditation in Germany, Ireland, and Arab countries. He continuously is transferring novel laboratory methods into clinical routine diagnostics. His work focuses on cellular immunology, with a strong focus on immune function and flow cytometry. His research is based on interdisciplinary research and on the interaction between the immune system and diseases conditions in tumors and chronic diseases.

In the fields of immunodiagnostics, psychoneuroimmunology, inflammatory diseases, and immuneoncology, he published around 300 research papers. He has been the chair of the IFCC Working Group Flow Cytometry from 2011 to 2018 and promoted education in recent flow cytometry, offering 16 flow cytometry courses in Europe, Asia, and South America, covering basic science, immunology, and hematology. The book“Cellular Diagnostics”, edited with Attila Tarnok and Gregor Rothe, has set standards for clinical cytometry within the last 10 years.

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