Isolation of Human Lymphocytes by Sedimentation

Abstract

Böyum separated white blood cells from erythrocytes by aggregating red blood cells and sedimenting them (1964). The same procedure was further elaborated by Böyum and applied for bone marrow cell separations (1968). Several modifications of this procedure have been published. The principle is aggregation of erythrocytes by chemicals which do not affect white blood cells. Sedimentation of aggregated erythrocytes can be achieved without centrifugation at room temperature, and the cells remaining in the supernatant can be sedimented by low speed centrifugation. In the procedure described here, the aggregating agent is Ficoll, a polysaccharide preparation. Sodium metrizoate is added to Ficoll to increase its density, thus preventing sedimentation of nonaggregating white blood cells while permitting the sedimentation of aggregated erythrocytes. The blood sample is layered in a tube on the mixture of Ficoll and sodium metrizoate. The aggregated cells will rapidly settle to the bottom of the container. In less than an hour at room temperature, without centrifugation, the supernate will contain only white blood cells, accumulated at the interface.