Analysis of PBPC cell yields during large-volume leukapheresis of subjects with a poor mobilization response to filgrastim.

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The circulating CD34 count is a reliable predictor of peripheral blood progenitor cell (PBPC) yields in subjects with a vigorous mobilization response to G-CSF, however, the value of this parameter in poor mobilizers is uncharacterized. Consecutive PBPC procedures (n = 81) with preapheresis CD34 counts less than 20 per microL (poor mobilizers) were compared with an equal number of good mobilizers (preapheresis CD34 counts > or =20/microL). G-CSF was administered at standard doses (10 microg/kg/day). CD34 yields correlated strongly with preapheresis CD34 counts in both good and poor mobilizers and were higher in allogeneic than autologous donors. For a standard 75-kg recipient, a CD34 cell dose of greater than 2 x 10(6) per kg was never achieved in less than two 15-L procedures if the preapheresis CD34 count was less than 8 per microL. Preapheresis WBC and MNC counts were lower in poor than in good mobilizers (28.4 vs. 43.0 and 3.25 vs. 5.01 x 10(3)/microL, respectively, p < 0.0001). Total WBC counts correlated more strongly with preapheresis CD34 counts, total CD34 yields, and CD34 yields per L processed in good mobilizers (R = 0.50, R = 0.44, and R = 0.42, respectively) than in poor mobilizers (R = 0.22, R = 0.02, and R = 0.01, respectively), whereas total MNC counts correlated more strongly with these parameters in poor (R = 0.38, R = 0.23, and R = 0.27, respectively) than in good mobilizers (R = 0.04, R = 0.13, and R = 0.16, respectively). CD34 cell yields correlate strongly with preapheresis CD34 counts. Based on this analysis, a CD34 count greater than or equal to 8 per microL is the threshold for performing PBPC collections in our institution.