Immunophenotyping

Flow cytometry passes a stained cell suspension through a laser beam and reads the light each cell gives off, so thousands of cells are measured in seconds and each population can be counted and identified by the markers carried on its surface. This is what separates one kind of leukaemia from another, what defines lymphoma subtypes, and what shows whether the immune system's helper and suppressor cells are in balance.

Panels are built around the clinical question, run with calibrated quality-control beads, and read together with the blood film and the patient's history rather than as an isolated printout.