The Use of Dextran as an Adjunct to Granulocyte Collection with the Continuous‐Flow Blood Cell Separator

High molecular weight dextran (dextran 110 or 150 in saline) was added to the input line of the continuous‐flow blood cell separator during a series of procedures for the collection of granulocytes from normal donors. Compared with procedures in which dextran was not used, there was enhanced sedimentation of red blood cells within the centrifuge bowl, and analysis of serial samples taken from the white blood cell line showed that contamination of the buffy coat by red cells was reduced by 88 per cent at the point where the granulocyte count was highest. The total leukocyte yields were 1.0 × 10 10 cells when dextran was not used (five procedures), 1.6 × 10 10 cells with dextran 110 (28 procedures), and 2.3 × 10 10 cells with dextran 150 (20 procedures), and there were corresponding increases in the numbers of granulocytes collected. The technique has proved safe and simple, and the addition of dextran is recommended as a means of increasing the leukocyte yield from normal donors while reducing the number of red blood cells collected.