Semicontinuous flow centrifugation for the pheresis of immunocompetent cells and stem cells.

Mononuclear cells from human peripheral blood were purified by semicontinuous flow centrifugation (SCFC) using the Haemonetics model 30 blood cell separator; 64% +/- 7% of the mononuclear cells in 600 ml of peripheral blood were collected in a 30-ml volume. Analysis of sequential 5-ml aliquots of the mononuclear cell concentrate revealed that both immunocompetent cells and granulocytic progenitor cells (CFU-C) were proportional to the cell count throughout the buffy coat. In vitro pheresis of large volumes of human bone marrow resulted in recovery of 63% of the cells, 12% of the hemoglobin, and 84% of the CFU-C in 20% of the original volume. Further centrifugation eliminated 80% of the platelets without loss of cells or CFU-C. SCFC of peripheral blood or bone marrow selectively concentrated mononuclear cells and reduced the contamination by granulocytes and erythrocytes. Large numbers of mononuclear cells can thus be collected for studies in vitro or for cryopreservation and the autologous reconstitution of immunosuppressed or myelosuppressed patients undergoing intensive antitumor therapy.