Role of Flow Cytometry in the Diagnosis of Benign Haematological Disorders

Flow cytometry (FCM), with its ability to rapidly analyse multiple parameters on individual cells, is an indispensable tool in haemato-oncology for the rapid diagnosis of various haematological neoplasms. However, FCM is also being increasingly used in the diagnosis of non-neoplastic haematological disorders affecting all three haematopoietic cell lines. Paroxysmal nocturnal haemoglobinuria (PNH) is an acquired stem cell disorder caused by the absence of glycosylphosphatidylinositol (GPI) anchored proteins on cell surfaces and is characterized by haemolysis, increased thromboses and bone marrow failure. Today, demonstration of the absence of GPI-anchored proteins by FCM is the gold standard for the diagnosis of PNH. Osmotic fragility testing using FCM and Eosin 5′ maleimide binding test has shown high sensitivity and specificity in the diagnosis of hereditary spherocytosis. FCM has also found use in the detection of feto-maternal bleeding in the investigation of Rh incompatibility. This technology can be used for the diagnosis of platelet function disorders even in the presence of severe thrombocytopenia, thus overcoming the biggest limitation of light transmission aggregometry, the gold standard in the diagnosis of platelet dysfunction. Primary immune-deficiency disorders are a heterogeneous group of genetic disorders. FCM appears to be a useful modality that provides a rapid diagnosis in many instances and at least guides genetic testing in others. FCM can be used for immunophenotyping or the detection of intracellular proteins as well as for functional assays. International guidelines and well-described protocols for performing FCM in non-neoplastic haematological disorders are available. This chapter will give an overview of the clinical uses of FCM for the diagnosis of non-neoplastic diseases of haematology, while also reviewing some protocols/guidelines available for performing these assays.