Higher infused CD34+ hematopoietic stem cell dose correlates with earlier lymphocyte recovery and better clinical outcome after autologous stem cell transplantation in non-Hodgkin's lymphoma

BACKGROUND: Lymphocyte recovery after autologous stem cell transplantation (ASCT) has been shown to be associated with positive clinical outcome in non-Hodgkin's lymphoma (NHL). This study sought to identify variables that affect lymphocyte recovery and survival after ASCT. STUDY DESIGN AND METHODS: A retrospective analysis of outcomes in 97 consecutive patients with NHL who underwent ASCT in a single center from August 1999 to January 2008 was conducted. RESULTS: A significant relationship was not observed between infused lymphocyte count and days to recovery of absolute lymphocyte count 500 × 106/L or greater after ASCT (ALC500; r = 0.139, p = 0.176), but there was a significant inverse correlation between infused CD34+ cell count and days to ALC500 (r = −0.333, p = 0.001). Univariately, infused CD34+ cell count and recovery of ALC500 by 20th day after ASCT were significant predictors of survival. The median overall survival (OS) and event-free survival (EFS) were significantly longer in patients who received 8.2 × 106 CD34+ cells/kg or more than in those who received fewer than 8.2 × 106 CD34+ cells/kg (OS, not reached vs. 11.6 months, p = 0.001; EFS, not reached vs. 4.8 months, p = 0.003). Multivariate analysis confirmed that infused CD34+ cell count was an independent prognostic factor for OS (p = 0.017) and EFS (p = 0.002). CONCLUSION: These data suggest that infused CD34+ cell count is predictive of kinetics of lymphocyte recovery after ASCT and is an independent prognostic factor for OS and EFS after ASCT in patients with NHL.