Using Flow Cytometry in Disease Diagnosis

Flow cytometry is a robust analytical technique that has rapidly become one of the standard analytical techniques used in medical research. This article will discuss the use of flow cytometry in disease diagnosis.

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What is flow cytometry?

Flow cytometry allows for the analysis of single cells in a population. This technique is analogous to microscopy, but instead of producing an image, a flow cytometer provides automated quantification of defined optical parameters of the cell or cell population being studied. Flow cytometry provides information on biological processes including apoptosis and cell adherence, as well as chromosome analysis and information on cell numbers and size.

Single cells are passed through the flow cytometer in a high-throughput manner and the entire process works according to the principles of fluid dynamics. The single cells flow down a flow cell (or tube) past a laser (or multiple lasers,) and cells are then analyzed by specialized computer software for defined fluorescence parameters and visible light scatter.

Flow cytometry is an incredibly versatile technique and many different variants of the technique have been developed in recent years. It has proven to be an invaluable analytical tool in the field of disease diagnosis. Vast numbers of cells can be analyzed in a matter of minutes, conferring advantages for study over other analysis methods.

Using fluorescence for analysis

Flow cytometry uses fluorescent markers to identify and analyze cell components. These include:

• DNA
• RNA
• Proteins
• Cellular signaling molecules

Light emitted in each cell can then be detected by the flow cytometer and the relative amount of each component can be measured due to its intensity. This is a crucial procedure for disease diagnosis and prognosis. It is known as immunophenotyping. The more fluorophore colors that a flow cytometer can detect allow for analysis of more components in a multiparameter manner.

Applications of flow cytometry in disease diagnosis and prognosis

Many diverse types of flow cytometry have been used in disease diagnosis and prognosis, such as conventional flow cytometry and imaging flow cytometry. Due to constant improvement and standardization of equipment and techniques, flow cytometers are now routinely used for diagnostic studies, especially for hematologic diseases.

Flow cytometry is used to perform the following tasks that are important for disease diagnosis:

• Blood cell counts
• Observing different types of leukocytes in a sample
• Sort T cells to determine how their function has been affected by an infection
• Determine the total DNA content in cells when performing tumor biopsies in cancer research
• Studying the effect of infectious diseases on individual cells with cell sorting
• Detection of pathogenic microbes in both biological and environmental samples
• Detecting minimal residual disease cells in bodily fluids.

In one notable application, flow cytometry has been used to identify the number of CD4+ vs. CD8+ T lymphocytes in blood samples for HIV research. This is used to determine whether the infection has progressed to AIDs, and how effective anti-HIV medication is.

Flow cytometry has fast become an essential technique in disease diagnosis. This is because it is a simple, fast method for study and diagnosis, identifying the spread of disease within the body, and informing effective treatment strategies.

Specific advantages of flow cytometry for disease diagnosis and public health

Flow cytometry confers several specific advantages for disease diagnosis and, hence, public health research. These include:

• Precision – Measurements are taken at the individual cell level provide a level of precision not found in bulk analysis methods. High sensitivity is achievable due to the ability to resolve fluorescent signals and analyze the data with small sample volumes.
• Versatility – Flow cytometry is an incredibly versatile technique. New fluorescent dyes and reagents are continuously being developed, and innovative technologies such as quantum dots have been integrated into flow cytometry research. Flow cytometers can provide useful data on lipids, nucleic acids, and proteins as well as characterize host-cell susceptibility and immune response, as well as identify pathogens.
• Robust analysis – Vast amounts of data can be gathered rapidly due to the robust, high-throughput nature of flow cytometry.

Public health outcomes, especially in outbreaks of disease, can be improved with the use of flow cytometry. Applications include:

• Monitoring the immune response of infected patients.
• Analysis of damage to hosts and proliferation of pathogens within the body.
• Providing environmental monitoring to rapidly detect emerging threats.

A robust, future-proof diagnostic technique

Although there are other analytical techniques in common use for disease diagnosis, the robust, precise, and versatile nature of flow cytometry means that it is unlikely to become obsolete any time soon. The increasing sophistication and accuracy of flow cytometers, the use of new fluorescent dyes and alternatives, and the introduction of new flow cytometry techniques all make the technique future-proof.

As well as this, the development of more sophisticated software and the application of machine learning to the technique means that the potential for this analytical technique is vast. Flow cytometry remains at the forefront of disease diagnosis and research, providing data that helps clinicians provide better outcomes for patients.

References:

• Janossy, G & Shapiro, H (2008) Simplified cytometry for routine monitoring of infectious diseases Cytometry B Clin Cytom. 74 Suppl 1:S6-10 [Accessed online 12^th August 2021] https://pubmed.ncbi.nlm.nih.gov/18228555/
• Doan, M et al. (2017) Diagnostic Potential of Imaging Flow Cytometry Trends in Biotechnology 36:7 oo. 649-652 [Accessed online 12^th August 2021] https://www.sciencedirect.com/science/article/pii/S0167779918300039
• Marrone, B.L, (2009) Flow Cytometry: A Multipurpose Technology for a Wide Spectrum of Global Biosecurity Applications JALA: Journal of the Association for Laboratory Automation 14(3) pp. 148-156 [Accessed online 12^th August 2021] https://journals.sagepub.com/doi/10.1016/j.jala.2009.03.001

Further Reading

• All Flow Cytometry Content
• Flow Cytometry Methodology, Uses, and Data Analysis
• Flow Cytometry Techniques used in Medicine and Research
• Flow Cytometry History
• Fluorescence-Activated Cell Sorting

Written by

Reginald Davey

Reg Davey is a freelance copywriter and editor based in Nottingham in the United Kingdom. Writing for News Medical represents the coming together of various interests and fields he has been interested and involved in over the years, including Microbiology, Biomedical Sciences, and Environmental Science.