What Is Flow Cytometry?

Medically Reviewed by Brunilda Nazario, MD on January 30, 2023
4 min read

Experts use flow cytometry to look at the features of cells or particles. They’ll take a sample of them and place them in a fluid. Then, they’ll look more closely at the fluid in a cytometer machine. In less than a minute, a computer can study about 10,000 cells during this process. Flow cytometry can help your doctor study certain diseases and diagnose conditions including leukemia or lymphoma.

Flow cytometry can show doctors many pieces of information. It can help them:

  • Count cells
  • Sort cells
  • Look at the functions and features of cells
  • Study biomarkers, which show that body functions are normal
  • Find microorganisms like bacteria, yeast, or fungus
  • Diagnose and sometimes treat blood and bone marrow cancers

To do flow cytometry, a lab worker or doctor will first take a sample of your blood, tissue, or bone marrow. Then, they’ll put it into a liquid. They’ll inject this liquid into the flow cytometer machine.

The cells will move into a line and then move in front of a laser beam, fluorescent light, and scattered light. Then, the machine will count and group the cells. A computer will keep all of this data.

In some cases, experts will test different types of cells in your body. They may look at blood and tissue cells at the same time. If this is the case, they’ll use multicolor flow cytometry. This approach will mark different cells with different colors. The flow cytometer machine will then organize the cells by their type and their color.

Another process in flow cytometry is called “gating.” With this, experts can identify and filter a certain type of cell. With gating, a researcher will choose a specific area on a chart on the computer. This tells the flow cytometry machine which cells it should look for and which cells it can leave out.

There are three main systems of a flow cytometry machine:

Fluidics. This system moves particles in a stream to the laser beam to take a closer look.

Optics. This has lasers to light up the particles in the sample and creates light signals.

Electronics. This system converts light signals into electronic signals so a computer can process them. In some machines, the electronics system can also sort particles.

After your test, experts will look at the results of your flow cytometry and create a lab report. They’ll look at the data alongside your medical history, physical exam, and any symptoms.

Your medical team will take a close look at the antigens, or markers, on your cells. If your doctor finds cells with a pattern of antigens that are in line with the type and maturity of the cell, that means they’re healthy cells. But if they find a different pattern, that could mean you have a certain disease.

Your doctor will talk to you about your results. They’ll explain what they mean and help you understand the next steps. They’ll give you all the details of your condition and go through treatment options, if that’s needed.

Usually, your doctor will use a flow cytometry test as a follow up to a complete blood count or white blood cell scan. They’ll want to use this test if your first scans showed that you have a higher number of lymphocytes than normal, immature blood cells, or abnormal cell counts.

With flow cytometry, your doctor can help figure out how serious your cancer might be. It can help them decide whether your cancer will respond well to a certain treatment. Your health care team may also use it to see if a disease has come back, or relapsed, since your treatment.

But your doctor might use flow cytometry at any point to look closer at your cells. It’s not just for cancer. In some cases, it might also help doctors study your DNA. Overall, flow cytometry helps experts understand more about certain conditions.

If you get results from a flow cytometry test that show cells that aren’t normal, it might mean that you have a form of cancer. Abnormal results in a flow cytometry tend to mean you have one of the following:

Besides cancer, flow cytometry can also find information about other conditions. It can help:

  • Find when an HIV infection has caused AIDS
  • See how well an HIV drug has worked
  • Look closer at other infectious diseases, autoimmune disorders, or immunodeficiencies (when your body doesn’t produce enough antibodies or cells to fight off germs)

Flow cytometry machines allow doctors to give you more personalized and accurate medical care. With this machine, your care team can find the best treatment option for your needs.