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Quality Control and Flow Cytometry:  What is it and why do it?

Posted on: May 22, 2019

Scientist in lab implementing quality control through flow cytometry

Flow cytometry (FC) is a sensitive and highly customizable technique that can be used in both preclinical and clinical studies. How do you ensure that flow cytometry data is reliable, consistent and can meet the standards required for regulatory requirements or clinical trials? Implementing quality control (QC) procedures is a widely accepted strategy to guarantee that your flow cytometry data is handled in a rigorous and consistent manner and can be used for regulatory compliance and clinical trial evaluations.

What is QC?

Laboratories use QC to guarantee that techniques and protocols satisfy the requirements set in place by the International Organization for Standardization (ISO) or outlined in similar standardization guidelines. These requirements involve internal quality control (IQC) procedures that are used daily in the lab and determine if a set of results can be considered accurate.

QC and FC

QC of FC protocols involves all aspects of the experiment, including the flow cytometer, reagents, methods, and samples. Routine instrument QC is required to guarantee that the flow cytometer is functioning properly, and these QC procedures check the optical alignment, detector sensitivity and linearity, and compensation levels. Daily QC measurements ensure that the instrument falls within predetermined standardized ranges for all of the required parameters.


Reagent QC is critical in order to control for lot-to-lot variability, which is an unavoidable issue related to FC analysis.  Protocols are used to validate that a given reagent, such as a fluorescently-conjugated antibody, works consistently within a pre-determined interassay coefficent of variation (CV). New batches of reagents are typically compared with existing batches that have been validated.

Biological controls are a critical element of the QC process as sample-to-sample variations can be challenging to address. Many FC assays use cells isolated from whole blood, and these specimens can come from fresh or previously frozen blood products. IQC of biological samples should use a sample that is either commercially available or frozen in large batches, as relying on fresh blood samples will be too variable. Commercially available controls and healthy control samples can be used together for method QC and to detect any problems in sample handling and processing.

QC for FC requires the expertise of experienced and technically proficient scientists and technicians who are familiar with QC procedures and documentation as well as the nuances of FC protocols.  This level of experience can be found in contract research organizations, where QC and validation are parts of the daily routine of these labs.

Consider how critical QC is to your FC protocols as you plan your next preclinical or clinical assay. You may want to consult with QC experts even in the planning phases of your studies to ensure you can satisfy any regulatory requirements tied to your studies.

Downlaod Infographic Best Practices in GLP for Flow Cytometry Assays

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