What should you know about TBNK flow cytometry?

TBNK refers to three lymphocyte groups: T cells, B cells, and natural killer cells. Flow cytometry uses labelled antibodies and a laser-based analyser to sort cells by their surface markers and physical features. The report may describe the presence, proportions, or marker pattern of these cells. It is one part of an assessment and is interpreted alongside symptoms, examination findings, blood counts, and other laboratory results.

A sample can come from blood or, in some situations, bone marrow. A [Bone Marrow Biopsy](/treatments/diagnostics-and-staging/bone-marrow-biopsy/) may be performed when marrow needs closer assessment. The broad method is described on the [Flow Cytometry](/technology/flow-cytometry/) page.

Ask whether your sample is blood or marrow and whether you need to change eating, drinking, or medicines beforehand. Tell the team about medicines that affect immunity and any recent infection. For a blood draw, keep the dressing in place as instructed. After a marrow procedure, follow wound-care advice and avoid strenuous activity for the period your clinician recommends. Keep the report and ask which findings require repeat testing or comparison with an earlier sample.

After a blood draw, seek advice for bleeding that does not settle with firm pressure. After marrow sampling, contact the service for increasing pain, spreading redness, drainage, fever, or a dressing that becomes soaked. Seek urgent help for fainting, severe weakness, trouble breathing, or confusion. The test itself does not diagnose every blood or immune condition, so urgent symptoms should be assessed separately from the result.

Ask which cell groups and markers were measured, whether the sample quality was adequate, and what the result means in your clinical context. Ask whether another test, blood count, or marrow assessment is needed. Clarify when the report is expected and who will explain an unexpected finding.