Buoyant density separation of human blood cells in renografin gradients

Renografin, because of its high density and low viscosity, has been shown to be suitable as a supporting medium for the construction of continuous density gradients. The conditions necessary for the isopycnic banding of cells were determined, initially, using human erythrocytes. In the order of increasing density, human blood cells were separated into relatively pure bands of nongranular leucocytes, erythrocytes, and granulocytes. Their relative positions in the gradient were affected, however, by the high osmolarity of Renografin. Renografin is not cytotoxic and does not aggregate cells. It has the additional advantages of being stable, readily obtained in sterile ampoules, and inexpensive.