Factors Affecting Allogeneic Peripheral Blood Stem Cell Mobilization in a Large, Ethnically, Diverse Population.

Abstract

Background: Reliable prediction of peripheral blood stem cell (PBSC) mobilization is useful in allogeneic PBSC transplantation, since yield may impact transplant outcomes and alter the approach to ex-vivo cell processing. Existing models to predict CD34 mobilization conflict and no studies have been conducted in a large, ethnically diverse population.Study Design: We studied 598 consecutive allogeneic PBSC collections performed in normal donors at least 18 years of age between 1999 and 2006. Mobilization consisted of subcutaneous G-CSF at either 10 ug/kg/d or 8 ug/kg/BID followed by large volume leukapheresis (LVL) on day 5. Within this group, 270 donors underwent an additional LVL (mean 12L) to collect lymphocytes within 2 days prior to initiation of mobilization. The lymphocyte collection was performed for potential future donor lymphocyte infusion (DLI). Donor demographics, self-reported ethnic backgrounds, PBSC yields and additional laboratory data were recorded for each procedure.Results: The study included 392 Caucasian (C), 65 African American (AA), 109 Hispanic (H) and 32 Asian Pacific (AP) adult donors (Table 1). There were no differences in gender distribution between groups; C donors were significantly older, while AP donors had lower BMI compared to other groups. Peak peripheral blood CD34 counts after mobilization were significantly lower in C donors compared to AA, H and AP donors (79 vs 105, 94 and 97 cells per uL, p<0.01), and were higher in donors with higher pre-G-CSF platelet counts and higher total doses of G-CSF received. Donors who underwent PBSC collection following a prior lymphapheresis also had significantly higher CD34 counts than donors who did not (95 vs 78 per uL, p<0.002). In multivariate analysis, ethnicity, total G-CSF dose, pre-G-CSF platelet count, and performance of prior LVL for DLI collection were significantly associated with CD34 mobilization.Conclusion: This study provides new information on factors which impact CD34 mobilization, which may be of potential benefit during planning for PBSC collection and subsequent cell processing.Table 1Donor demographics, peripheral blood CD34 counts and CD34 yieldsCharacteristicAllCaucasianAfrican−AmericanHispanicAsian−PacificP*N5983926510932% Male5151525050nsAge (yrs)40 ±1343 ±1338±1035±1236±12<0.05Weight (kg)79±1880±1982±1675±1768±16<0.01Height (cm)170±10172±10172±10166±10166±11<0.05BMI (kg/m2)27±527±528±527±525±5<0.05Peripheral blood CD34 (per uL)**86±5279±49105±5894±4997±73<0.01CD34 yield (106/L)***35±2233±2143±2735±2037±25<0.01*For ANOVA comparison among all groups. **Absolute number of circulating CD34 cells in peripheral blood per uL measured after 5 days of G-CSF mobilization and prior to apheresis. *** Total CD34 yield per Liter processed during LVL