Preapheresis WBC, mononuclear cell and CD34+ cell counts as predictors of optimal timing of peripheral blood stem cell collection

Kim, Mun Jeong; Park, Quehn; Lim, Hyun Sook; Kim, Hyun Ok; Min, Yoo Hong; Lyu, Chuhl Joo; Nahm, Chung Hyun

Abstract

BACKGROUND
Peripheral blood stem cells (PBSC) transplantation has been widely used as a substitute of bone marrow transplantation in patients with hematologic malignancies and solid tumors. Because, PBSC harvest by serial daily apheresis procedure is expensive and time consuming, it is important to determine the best time to start the collection for reducing the number of apheresis procedure. We analyzed our experiences of PBSC collections and evaluated the preapheresis hematologic parameters that may predict the PBSC yields.
METHODS
One hundred seventy six PBSC harvests from seventy cancer patients (median age : 32 yrs; fourty five males and twenty five females) were performed using our large volume leukapheresis protocol (total blood volume processed : over three total blood volume) after chemotherapy and infusion of G-CSF. Peripheral blood obtained immediately before the start of apheresis was analyzed for total WBC, mononuclear cell (MNC), and CD34+ cell counts. Total WBC, MNC, and CD34+ cell count were performed on selected samples of PBSC from each patient before freezing for determining the PBSC yields. Linear regression analysis was performed on logarithmized data whether preapheresis WBC, MNC, and CD34+ cell counts on the day of harvest in the peripheral blood might correlate well with the PBSC yield, respectively. RESLUTS: With the use of linear regression analysis, preapheresis WBC counts and MNC counts were not correlated significantly with the CD34+ cell yield in PBSC harvests (WBC/microliter in PB vs. CD34+ cell/kg in harvests, r=0.35, p=0.10; MNC/microliter in PB vs. CD34+ cells/kg in harvests, r=0.42, p=0.07). But the CD34+ cell count (CD34+ cells/microliter in peripheral blood) correlated most closely with the progenitor cell yield in the corresponding leukapheresis product (CD34+ cells/kg body weight, r=0.75, p<0.001). A number of 20 circulating CD34+ cells/microliter blood ensured 2.0 x 106 CD34+ cells/kg, that is known to be a threshold dose for rapid hematologic recovery, and the best time for the collection on the same day by a single leukapheresis in more than 85% cases.
CONCLUSIONS
The number of CD34+ cells/microliter blood allows a reliable prediction of the CD34+ progenitor cell yield in subsequent leukapheresis procedure, while WBC and MNC counts did not predict the progenitor cell yield. A level of more than 20 CD34+ cells/microliter indicates that the threshold quantity of 2.0 x 106 CD34+ cells/kg is likely to be obtained by a single leukapheresis processing 15~20 liters of peripheral blood.