Cell Separation Using Flow Cytometric Cell Sorting
I. INTRODUCTION Flow cytometric cell sorting rapidly separates cells one at a time based primarily on optical and fluorescent properties. Fluorescent dyes to specific cellular targets or antibodies (Abs) tagged with fluorochromes are used to identify particular cells. Cells in liquid suspension flow past a sensing zone and are analyzed for the optical signal they emit. Analysis rates can be greater than 10,000 cells/s. Cells whose optical characteristics fall within preselected ranges or “gates” generate an electronic signal that initiates sorting of the cell. Less than one millisecond after a wanted cell is analyzed, it can be physically separated. Some early researchers coined the acronym FACS (fluorescenceactivated cell sorting) for this technique, and FACS™ is currently a trademark of Becton Dickinson Immunocytometry Systems. Since characteristics other than fluorescence can be used to analyze the cells, this chapter will use a more general term, flow sorting, for this technique.