From Traditional to Crude Collection Efficiency: A Comprehensive Analysis of the Impact of Processed Volume

Calculating the collection efficiency (CE) of CD34+ cells in leukocytapheresis (LVL) is critical to understanding the performance of cell collection. Traditional CE values are typically based on both pre- and post-apheresis calculations of the pooled cells (CE1), or they may be based only on the pre-procedure pool calculation (CE2) and total blood volume (TBV) processed. However, determining the actual CD34+ concentration in peripheral blood (PB) during LVL is more problematic. New crude CE (CruCE) takes into account the recruitment and extraction of CD34+ cells during LVL. This study aims to retrospectively compare traditional (CE2, CE1) and CruCE and to assess the variables that influence new CruCE-including donor characteristics, procedure characteristics, and device setting parameters-in both large-volume LVL and non-LVL. Data from adult donors who underwent autologous and allogeneic collections of PB stem cells between January 2020 and April 2023 were retrospectively included. Our series comprises 123 autologous and 37 allogeneic LVL procedures. The median of CD34+ CE2, CE1, and CruCE was 51%, 65%, and 74% in autologous donors and 58%, 69%, and 76% in allogeneic donors. In multivariate analysis, TBV processed and prior CD34+ cell count in PB showed a positive and a negative correlation with CruCE in autologous and allogeneic settings, respectively. In conclusion, CruCE may be closer to actual CE in comparison to CE2 and CE1. LVL and low CD34+/μL prior to the procedure may enhance CD34+ cell CE.