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 Flow Cytometry

 ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​What is flow cytometry?

  • Flow cytometry involves the analysis of cells incubated with fluorescently tagged antibodies. These cells flow past several different lasers, providing information on individual cell size, internal and nuclear complexity, and specific antibody binding.
  • This analysis, most commonly used to characterize lymphoid cells, allows for the further characterization of cells in samples such as blood, cavitary fluids, and in liquid suspensions of tissue aspirates (such as lymph nodes for example).
  • This data helps determine whether a sample is reactive vs. neoplastic. It also helps further determine cell phenotype (B vs. T-cell for example), and can aid in the prognostication of lymphoid malignancies.

 When should I order flow?

  • Flow cytometry is recommended in cases of confirmed or very strongly suspected solid tissue lymphoma. Examples include phenotyping confirmed large cell lymphomas and confirming a suspected case of intermediate sized lymphoma, in which the node is comprised of a homogenous population of intermediate sized lymphocytes.
  • It’s also used in blood samples to confirm suspected cases of leukemia and further characterizing diagnosed cases.

 Antibody Panels

  • Flow cytometry is currently limited to dogs and cats.
  • Dog:
    • T-cell: CD3, CD4, CD5, CD8
    • B-cell: CD21
    • Others: CD14, CD18, CD34, CD45, MHCII
  • Cats:
    • T-cell: CD4, CD5, CD8
    • B-cell: CD21


  • Flow cytometry can’t always distinguish inflammation/infection from neoplasia. An important example of this phenomenon is the expansion of CD8+ T-cells that can occur with E. canis infection. As with any lab test, flow cytometry results should always be interpreted in light of other clinical signs, history, and prior lab testing. Providing a thorough, relevant history also enables our pathologists to provide the most accurate, thorough diagnosis possible.
  • Because flow cytometry involves the analysis of individual cells, samples with low cell concentrations of interest are more difficult to analyze. For this reason, flow cytometry may not be the best test for blood samples with <5,000 cells of interest. In these cases, discussion with a pathologist is advised.
  • Please see the test menu link below which provides further submission requirements and sample guidelines. Cell viability should be preserved if recommended guidelines are followed. If a sample is non-viable upon analysis, you won’t be charged for the full assay, and instead will be billed for viability testing only.
  • As with any test, if you have any questions about flow and its possible application to a specific case, please don’t hesitate to call, as one of our pathologists will be happy to discuss it further with you!

 Resource Links

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