What should you know about staining cells for flow cytometry?

A laboratory prepares a sample of blood, bone marrow, tissue or another body fluid as a suspension of individual cells. Antibodies attach to chosen proteins on the cell surface or within the cell. Each antibody carries a fluorescent label. As cells pass one at a time through the flow cytometer, lasers excite the labels and detectors record the pattern of signals.

The pattern helps identify groups of cells, compare their features and find an unusual population. Controls help the laboratory distinguish true staining from background signal. Results are interpreted with the sample type, symptoms and other test findings; staining by itself is not a diagnosis.

Usually, staining happens in the laboratory after a sample has been collected, so it does not add a separate procedure. The sample may come from a blood draw or a bone marrow biopsy, depending on the question. Ask how the result will be reported, which cell markers are being tested and whether another sample or test may be needed.

Staining itself does not cause patient symptoms because it is performed on a collected sample. Seek advice for problems related to sample collection, such as persistent bleeding, increasing swelling, fever or worsening pain after a biopsy. Ask the collecting team when the result is expected and whom to contact if the site changes.

Ask what cell population the test is investigating, whether the sample was adequate, and how the marker pattern may affect the next step. You can also ask whether flow cytometry is being used to support a diagnosis, classify a condition or monitor treatment.