Standardization between instruments

Introduction

In flow cytometry immunophenotyping, it is essential that results are comparable among laboratories, distinguishing true biological changes from technical artifacts.^1, 2

Flow cytometry standardization is a complex procedure widely reviewed in the literature,^4, 5 which includes many other concepts like panel marker design, sample processing, system setup and instrument performance monitoring. From a user point of view, the most difficult aspects to control are: instrument setup, performance monitoring, compensation matrix calculation and the setting of voltage/gain applied to each fluorescence detector.

Daily instrument performance monitoring ensures reproducibility of the analysis and also standardizes the positions of cell clusters in histograms obtained from different instruments.³ By setting voltage/gain to place the control particles at a particular target channel, a relatively similar instrument setup is achieved.^4, 5 If one or more parameters are out of range from the target MFI (Mean Fluorescence Intensity), the system performance could be compromised. In case a readjustment is needed, the voltages/gains modification and the application of these changes to the panel’s settings must be done manually. This makes standardization among different instruments difficult and time consuming.

The new DxFLEX instrument includes a QC/Standardization module that automatically enables instrument quality control and standardization procedures. Quality control checks the adequate signal strength and precision of the instrument. The module monitors the MFI, tracks gain changes for any specific assay and directly links them to the panel experiment settings for automatic modifications.

Simplified standardization setup workflow on one or between DxFLEX platforms

In order to improve consistency and reduce variation between instruments DxFLEX system provides a simplified and reliable standardization workflow, while delivering consistent results on cell samples across instruments.

The DxFLEX platform provides a built-in standardization function in the CytExpert for DxFLEX software, which enables daily auto-calibration of gain settings under user-defined target values and implements the same target values on different DxFLEX platforms for the same application.

DxFLEX targets obtained with Flow-Set Pro Fluorospheres after gain optimization. Data for illustrative purposes only.

References

1. Lacombe, F. et al. Harmonemia: a universal strategy for flow cytometry immunophenotyping-A European LeukemiaNet WP10 study. Leukemia 30, 1769–1772 (2016).
2. Kalina, T. et al. EuroFlow standardization of flow cytometer instrument settings and immunophenotyping protocols . Leukemia 26, 1986–2010 (2012).
3. Schwartz, A., Marti, G. E., Poon, R., Gratama, J. W. & Fernández-Repollet, E. Standardizing flow cytometry: A classification system of fluorescence standards used for flow cytometry. Cytometry (1998). doi:10.1002/(SICI)1097-0320(19981001)33:2<106::AID-CYTO4>3.0.CO;2-H
4. Maecker, H. T., McCoy, J. P. & Nussenblatt, R. Standardizing immunophenotyping for the Human Immunology Project. Nat. Rev. 12, 191–200 (2012).
5. Perfetto, S. P., Ambrozak, D., Nguyen, R., Chattopadhyay, P. & Roederer, M. Quality assurance for polychromatic flow cytometry . Nat. Protoc. 1, 1522–1530 (2006).

DxFLEX is an IVD instrument that is available only in countries where the regulatory approval is obtained from the local regulatory agencies. Please check with your local sales representatives before placing your orders.

Flow-Set Pro Fluorospheres: For In Vitro Diagnostic Use. Rx Only in the U.S.A.

Flow-Set Pro Fluorospheres have not been validated as part of the DxFLEX system and are only meant to serve as an example to demonstrate the general standardization process. DxFLEX Daily QC Fluorospheres or any other reference material that is relevant for your applications may be used as the standardization samples.