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.