Presently, the need for methods involving separation, identification, and characterization of different kinds of cells is amply realized among immu­ nologists, hematologists, cell biologists, clinical pathologists, and cancer researchers. Unless cells exhibiting different functions and stages of differ­ entiation are separated from one another, it will be exceedingly difficult to study some of the molecular mechanisms involved in cell recognition, specialization, interactions, cytotoxicity, and transformation. Clinical diag­ nosis of diseased states and use of isolated cells for therapeutic (e. g. , immunotherapy) or survival (e. g. , transfusion) purposes are some of the pressing areas where immediate practical benefits can be obtained by applying cell separation techniques. However, the development of such useful methods is still in its infancy. A number of good techniques exist based either on the physical or biological properties of the cells, and these have produced some valuable results. Still others are to be discovered. Therefore, the purpose of this open-end treatise is to acquaint the reader with some of the basic principles, instrumentation, and procedures pres­ ently in practice at various laboratories around the world and to present some typical applications of each technique to particular biological prob­ lems. To this end, I was fortunate to obtain the contribution of certain leading scientists in the field of cell separation, people who in their pioneer­ ing work have struggled with the particular problems involved in separating living cells and in some way have won.

1 Transient Electrophoretic and Sedimentation Analysis of Cells in Density Gradients.- I. Introduction.- II. Instrumentation.- III. Data Acquisition and Processing.- IV. Methodological Aspects.- V. Applications to Cell Analysis.- References.- 2 Electrophoretic Light Scattering and Its Application to the Study of Cells.- I. Introduction.- II. Principles of Electrophoretic Light Scattering.- III. Cell Electrophoretic Light Scattering.- IV. Conclusion.- References.- 3 Cell Separation by Endless Fluid Belt Electrophoresis.- I. The Objective.- II. Rotational Suppression of Thermal Convection.- III. The Circular Endless Belt Apparatus.- IV. The Noncircular Endless Vertical Belt Apparatus.- V. Endless Belt Electrophoresis as a Form of Deviation Electrophoresis.- VI. Properties of the Endless Belt System.- VII. Modes of Operation.- VIII. Thermal Convection Artifacts.- IX. Preparative Instrument with Removable External Magnets.- X. Preparative Instrument with Submerged Magnets.- XI. The "Fan" Collector for Increased Resolution.- XII. Operation of the Instrument.- XIII. Measurement of Electrophoretic Mobilities.- XIV. Examples of Electrophoretic Separation of Living Cells by Endless Belt Electrophoresis.- XV. Theoretical Considerations.- XVI. Resolving Power.- References.- 4 Buoyant Density Separation with Linear Gradients of Bovine Serum Albumin and Analysis by Centrifugal Cytology and Flow Techniques.- I. Introduction.- II. Gradient Separation Method.- III. Past Procedures for the Preparation of Fixed Stained Cells from Dilute Suspensions.- IV. Centrifugal Cytology.- V. The Isolation of Heteroagglutinates.- VI. Combined BSA Gradient Centrifugal Cytology Studies.- VII. The Design and Implementation of a Flow Analyzer for Cell Separation Studies.- VIII. Conclusion.-References.- 5 Physical Separation and Characterization of Reticulocytes and Other Cell Fractions from Rat Bone Marrow, and the 1g Mini-Staflo.- I. Introduction.- II. The lg Mini-Staflo.- III. Model Experimental Studies and Theory.- IV. Rat Bone Marrow Cell Separation.- V. Discussion.- VI. Summary and Conclusions.- References.