Flow cytometry allows phenotyping characterisation of cell populations by analysing surface or intra-cytoplasmic markers of single cells, combined with light scatter properties. Multiparameter flow cytometry (MFC) is the process whereby multiple markers are analysed simultaneously, allowing for more accurate phenotypic characterisation. It plays an important role in haematology diagnosis and monitoring of response to treatment.

Detailed knowledge of flow cytometry methodology, gating strategies and maturation pathways is not required for the FRCPath Haematology examination. Knowledge of common immunophenotypes and lineage markers should suffice.

The analysis of SSc against CD45 expression provides a simple, reproducible method for distinguishing the major cell lines in peripheral blood and bone marrow specimens. In this example, the various lineages are labelled.