Density gradient isolation of peripheral blood mononuclear cells using a blood cell processor.

Large numbers of mononuclear cells (MNC) are needed for hematologic reconstitution using peripheral blood stem cells. The possibility of isolating those cells by discontinuous Ficoll-diatrizoate density gradient centrifugation in two blood cell processors (the Haemonetics V50 [V50] and the Cobe 2991 [2991]) were examined. Buffy coats from peripheral blood containing 6.23 X 10(8) MNC were separated in the V50, resulting in a recovery of 75 percent. The purity of the cells, defined as the percentage of lymphocytes and monocytes among all leukocytes, was 95 percent. With larger cell loads (3 to 7 X 10(9) MNC), the yield was higher in the V50 than in the Cobe 2991 (92 versus 75%). After separation in the V50 or the 2991, the cloning efficiencies of hematopoietic progenitor cells (CFU-GM and BFUe) were not different from those of cells isolated on 5 ml Ficoll-diatrizoate gradients in centrifuge tubes. Both leukapheresis and MNC separation can be carried out with the same bowl and tubing set in the V50. With that approach, an average of 6 X 10(9) MNC were processed in 16 experiments. An average recovery of 82 percent with 95 percent purity was achieved. The authors conclude that, in terms of simplicity of operation, cost effectiveness, and maintenance of sterility, the V50 may be better suited than the 2991 for the purification of MNC from peripheral blood.