Kinetics of peripheral blood stem cell harvests during a single apheresis

BACKGROUND: The enumeration of CD34+ cells in the peripheral brood of patie nts before leukapheresis is commonly used to predict the outcome of stem ce ll harvests. The concept that an increased number of transplanted cells giv es faster marrow reconstitution triggers an interest in investigating the k inetics of peripheral blood stem cells during leukapheresis. The aim of thi s study was to investigate the issue of recruitment of hematopoietic progen itor cells during a single leukapheresis. STUDY DESIGN AND METHODS: Nine leukapheresis procedures (in 8 patients) wer e investigated. In each case, 3 blood Volumes were processed. Samples from peripheral blood, the collection line of apheresis equipment, and the colle cted component were obtained after each blood volume was processed. The enu meration of CD34+ cells was performed, and the total number of progenitors, as a sum of the number of cells in the peripheral blood and the number of cells in the collected component, was calculated. RESULTS: A mean of 13.3 L of blood was processed, and a component with a me an Volume of 424 mt and a mean of 10.1 x 10(6) CD34+ cells per kg of body w eight was collected. White cell and mononuclear cell counts in peripheral b lood declined concomitantly during the procedures. The calculated total num ber of cells-that is, the sum of the number of cells in the collected compo nent and the number of cells in the peripheral blood-showed a concomitant, but not equal, rise in polymorphonuclear cells, mononuclear cells, and CD34 + cells during the leukapheresis. This apparent mobilization of progenitors into the peripheral blood did not correlate with the slightly increased nu mber of polymorphonuclear cells or with the more pronounced increase in mon onuclear cells. CONCLUSION: There is a substantial recruitment of progenitor cells during a single leukapheresis.