Differential analysis of human leukocytes by dielectrophoretic field-flow-fractionation.

The differential analysis of human leukocytes has many important biological and medical applications. In this work, dielectrophoretic field-flow-fractionation (DEP-FFF), a cell-separation technique that exploits the differences in the density and dielectric properties of cells, was used to separate the mixtures of the major human leukocyte subpopulations (T- and B-lymphocytes, monocytes, and granulocytes). The separation was conducted in a thin chamber equipped with an array of microfabricated interdigitated electrodes on the bottom surface, and the separation performance was characterized by on-line flow cytometry. To investigate optimal separation conditions for different leukocyte mixtures, elution fractograms at various DEP field frequencies were obtained for each leukocyte subtype. With appropriately chosen conditions, high separation performance was achieved in separating T- (or B-) lymphocytes from monocytes, T- (or B-) lymphocytes from granulocytes, and monocytes from granulocytes. DEP-FFF does not involve cell-labeling or cell-modification step, and provides a new approach to hematological analysis.