Circulating hematopoietic progenitors and CD34+ cells predicted successful hematopoietic stem cell harvest in myeloma and lymphoma patients: experiences from a single institution

BACKGROUND Previous studies have shown that the numbers of both circulating hematopoietic progenitor cell (HPC) and CD34(+) cell are positively correlated with CD34(+) cell harvest yield. However, the minimal numbers of both circulating HPCs and CD34(+) cells required for performing an efficient hematopoietic stem cell (HSC) harvest in lymphoma and myeloma patients have not been defined in our institution. PATIENTS AND METHODS Medical records of 50 lymphoma and myeloma patients undergoing peripheral blood HSC harvest in our institution were retrospectively reviewed. The minimal and optimal HSC harvest yield required for the treatment was considered to be ≥2×10(6) CD34(+) cells/kg and ≥5×10(6) CD34(+) cells/kg, respectively. RESULTS The minimally required or optimal HSC yield obtained was not influenced by age (≥60 years), sex, underlying malignancies, disease status, multiple rounds of chemotherapy, or history of radiotherapy. The numbers of both circulating HPC and CD34(+) cell were higher in patients with minimally required HSC yields (P=0.000 for HPC and P=0.000 for CD34(+) cell) and also in patients with optimal HSC yields (P=0.011 for HPC and P=0.006 for CD34(+) cell). The cell count cutoff for obtaining minimally required HSC harvest was determined to be 20/mm(3) for HPCs and 10/mm(3) for CD34(+) cells. Furthermore, the cell count cutoff for obtaining optimal HSC harvest was determined to be 60/mm(3) for HPCs and 35/mm(3) for CD34(+) cells. CONCLUSION A total of 60/mm(3) of HPCs and 35/mm(3) of CD34(+) cells in peripheral blood predicted optimal HSC harvest in lymphoma and myeloma patients.