Transfus. Sci. Vol.16, No.4, pp. 301-302, 1995 Copyright © 1995 Elsevier Science Ltd Printed in Great Britain. All rights reserved 0955-3886/95 $9.50 + 0.00
Theme Editorial John Freedman, MD, FRCPC
Transfusion Medicine has become a multidisciplinary field with incorporation of new techniques and technologies. This issue of Transfusion Science addresses flow cytometry. Laser-based flow-cytometric analysis is a relatively recent technology that has had widespread application in medical and biological research. The continuing extraordinary growth of new applications for flow cytometry has, aided by improvements in instrumentation, dyes, monoclonal antibodies, in methods of cell preparation and staining and trends to automation, moved the technology for many applications from the research to the clinical laboratory. Advantages of flow cytometry include the capability to make measurements on single cells with speed, sensitivity, precision and objectivity. Results can be stored as computer files, allowing ready access to reassess and reanalyze past experiments. Results may be qualitative, semiquantitative or quantitative and a recent publication indicated that flow cytometric Scatchard plots show less scatter and may be superior to radioactive ligand measurements, especially at low ligand concentrations.1 Using flow cytometry, a wide range of cellular features, functional attributes and subcellular constituents can be analyzed. These include examination of cell surface proteins, as is used in immunophenotyping, perhaps the most widely used clinical application, with emphasis on mononuclear cells of the blood, bone marrow and lymphoid tissues, as well as platelets and reticulocytes. The sensitive capacity for rare event analysis may be useful for residual or recurrent malignancy and for a number of applications pertinent to red cell analysis in the Transfusion laboratory. In the clinical laboratory, probably the second most common application of flow cytometry is in measurements of DNA, e.g. differentiating live and dead cells, cell cycle analysis, S-phase determinations, apoptosis and detection of cell proliferation-associated proteins. Other assays amenable to flow cytometry include evaluation of living cells for intracellular pH, intracellular ionized calcium, cell membrane potential, leukocyte oxidative and phagocytic function and lysosomal proton pump activity. Methods have been developed for assays of cell enzyme activity, glutathione content and drug effects on cells, as in multi-drug resistance. There has also been considerable work on chromosome analysis and sorting and, recently, flow cytometry has been applied to in situ PCR and FISH assays. The technology has been used to study many types of cells, including sperm, yeast, bacteria, algae, plant and insect cells. In the clinical laboratory, flow cytometry has been applied to examine all of the cells of the blood. In Transfusion Medicine, it has yielded new insights into pathophysiological and diagnostic investigations in the blood transfusion laboratory. The six papers presented concentrate on hematologic applications. Following an introduction on the principles of flow cytometry, the major applications of flow cytometry in diagnosis of hematologic malignancy and in monitoring patients with acquired i m m u n e deficiency syndrome (AIDS) are presented. The remaining three papers focus on the use of flow cytometry in Transfusion Medicine, dealing with white and red Department of Immunohematology and Cellular Immunology, St Michael's Hospital, University of Toronto, 30 Bond Street, Toronto, Ontario, Canada MSB 1W8. 301
302 Transfus. Sci. Vol. 16, No. 4 blood cells and platelets, respectively. These overviews are not meant to be exhaustive, but hopefully will whet the appetite of the reader and stimulate new investigations for the clinical and the research laboratory in Transfusion Medicine. REFERENCE
1. Gordon IL: Scatchard analysis of fluorescent Concanavalin A binding to lymphocytes. Cytomerry 1995; 20:238-244.