Associations among white blood cells, CD34+ cells and GM-CFU in predicting the optimal timing of peripheral blood stem cell collections by apheresis.
OBJECTIVE
To analyze preapheresis blood CD34+ cells and corresponding apheresis products in order to investigate whether peripheral blood CD34+ cell counts correlate with peripheral blood progenitor cell (PBPC) yields and to determine the optimal timing for starting PBPC collections in our clinical setting.


METHODS
Thirty-eight patients with hematological malignancies and undergoing varied mobilization regimens were enrolled. White blood cell counts (WBC), CD34+ cells and granulocyte-macrophage colony-forming units (GM-CFU) enumeration were performed on blood samples taken immediately prior to each apheresis procedure and in the corresponding PBPC collection.


RESULTS
A total of 61 apheresis procedures were performed, with a median of two collections per patient (range 1-3). The number of CD34+ cell/ml in the preapheresis blood correlated closely with CD34+ cells/kg and, to a lesser degree, with GM-CFU/kg in the apheresis products (r = 0.81 and r = 0.67, respectively, P < 0.0001). WBC showed significant but poor correlation with CD34+ cells/kg and GM-CFU/kg (r = 0.43 and r = 0.45, respectively, P = 0.004). A significant correlation was also found between CD34+ cells/kg and GM-CFU/kg in PBPC collections (r = 0.62, P < 0.0001). Linear regression analysis indicated that the minimum threshold of 2 x 10(6) CD34+ cells/kg might be attained with a single apheresis if the CD34+ cells/ml in the peripheral blood measured prior to apheresis on the day of collection is > or =26 x 10(3) CD34+ cells/ml.


CONCLUSIONS
Collectively, these data demonstrate that circulating CD34+ cells is more useful than GM-CFU or WBC for predicting the optimal timing of PBPC harvests.
Boulassel
M R
MR
Division of Hematology, Royal Victoria Hospital, McGill University Health Centre, Montreal, Quebec, Canada.
D000328:Adult; D000368:Aged; D018952:Antigens, CD34 / Q000097:blood*; D001781:Blood Component Removal; D005260:Female; D006098:Granulocytes / Q000166:cytology*; D019650:Hematopoietic Stem Cell Mobilization; D018380:Hematopoietic Stem Cell Transplantation; D006801:Humans; D007958:Leukocyte Count; D008228:Lymphoma, Non-Hodgkin / Q000628:therapy; D008264:Macrophages / Q000166:cytology*; D008297:Male; D008875:Middle Aged; D009101:Multiple Myeloma / Q000628:therapy
D018952:Antigens, CD34