Dynamics of monocyte count: a good predictor for timing of peripheral blood stem cell collection

To investigate potential predictive parameters for successful collection of autologous peripheral blood stem cells (PBSC), 60 consecutive first mobilization attempts and 145 leukapheresis procedures for patients with hematologic malignancies (multiple myeloma: n = 20; acute leukemia: n = 27; lymphoma: n = 13) were analyzed. All patients underwent chemotherapy and granulocyte-colony stimulating factor combined mobilization protocols. PBSC collection began when white blood cell (WBC) count rebounded to >1.0 × 10(9)/L. Poor mobilization (PM) was defined as <2.0 × 10(6)/kg of ideal body weight CD34+ cells were collected from at least three leukapheresis procedures. PM incidence was 15% (9/60). On the first apheresis day, CD34+ cell yield was closely associated with the final yield. Failure to reach the first-day target of 0.7 × 10(6) CD34+ cells/kg was perfectly matched with PM. Circulating WBC and monocyte (MO) counts preleukapheresis had a positive correlation with final CD34+ cell yield. For the first-day apheresis target, receiver operator characteristic (ROC) curve analysis showed that MO count had an area under the curve (AUC) of 0.806 (P = 0.004). An optimal predictive cutoff value for MO count was 1.455 × 10(9)/L with both high sensitivity and specificity of 0.739 and 0.899, respectively. Patients who began leukapheresis with an MO count of ≥1.455 × 10(9)/L accomplished more successful first-day collections than those of their counterparts (P = 0.021). ROC analysis also showed preapheresis WBC count had a high AUC of 0.768 (P = 0.012). However, we could not find a WBC indicator to initiate leukapheresis. In conclusion, circulating MO count after mobilization is a helpful parameter to determine the optimal time point for starting a PBSC collection.