Apheresis product total CD34 cell count prediction at peripheral stem cell collection via a formula: A multicenter study.

Introduction: Effective mobilization of Stem Cells(SCs) to peripheral blood (PB) is crucial for obtaining sufficient CD34 cell numbers via apheresis. The ratio of pre-apheresis PB CD34 cells is the best parameter for predicting the product CD34 cell count. However, quantitating CD34 PB cells requires flow cytometry, which usually takes two or more hours to obtain the results. We hypothesized that the product CD34 cell count could be predicted using the counts of white blood cells (WBCs), mononuclear cells (MNCs), and pre-apheresis CD34 cells. A formula that achieves this would substantially affect the efficiency and effectiveness of apheresis. We, therefore, aimed to estimate the number of CD34 cells in the product using a formula that incorporates pre-apheresis PB WBC, MNC, and CD34 cell counts and product WBC and MNC counts.

Methods: We examined the results of 373 leukapheresis procedures for SC mobilization. Effective separation of CD34 PBSCs (count/μL) via apheresis was estimated using the following formula: [Product WBC (count/μL) × MNC (count/μL) × pre-apheresis CD34 cell (percentage/μL)] ÷ [PB WBC count/μL × PB MNC (count/μL)].

Results: A strong correlation was observed between the CD34 cell count calculated using our formula and the post-apheresis CD34 cell count measured via flow cytometry (R = 0.939, based on linear regression analysis). In the subgroup analysis, this correlation was observed for all the disease subgroups and healthy donors.

Conclusion: We developed a formula that predicts the product CD34 cell count and is useful for determining whether a second apheresis procedure will be required.