Flow cytometry is a universally used method for sorting cells from biological samples. Cells, first given fluorescent tags which can be excited by a laser system, are then processed through a machine called aflow cytometer. The flow cytometer acts to excite, separate, count and collect the tagged cells. Flow cytometry facilities exist in all major biomedical and biological research centers. The techniques described in Flow Cytometry, Second Edition are essential to today's basic and clinical researchers. Rapid progress in this area necessitates updating the first edition with the second. In addition, the expansion of the field reflects a growing international market among individuals, central facilities and libraries, and international coursebook users.