Determining factors predictive of CD34+ cell collection efficiency in an effort to avoid extended and repeated...

Collection efficiency (CE) is a reflection of the proportion of cells passing through a cell separator that is harvested. The aim of our study was to evaluate which factors influence CE independently in order to find ways to improve CE and therefore minimize the costs and risks of leukapheresis and graft processing.

A total of 206 consecutive apheresis procedures performed on 128 donors/patients were studied retrospectively. We explored the association between CE and the following factors: age, sex, weight, mobilization (granulocyte-colony-stimulating factor with or without chemotherapy), collection type (autologous versus allogeneic), venous access (peripheral versus central), total processed blood volume (TPV), hematocrit, white blood cell (WBC) count, thrombocyte count, and peripheral blood CD34+ cell concentration (PBCD34+).

Stepwise multiple regression analysis showed WBC count to be the single best predictor of CE, accompanied by TPV. When performing subgroup analysis for autologous apheresis procedures, the inverse correlation of WBC count and TPV with CE becomes stronger (r = -0.563 with P < 0.001 and r = -0.198 with P = 0.020 respectively), whereas those correlations disappear when analyzing only allogeneic apheresis procedures.

The negative correlation between TPV and CE present only in autologous collection procedures can be explained by the limited intra-apheresis recruitment of CD34+ cells into the blood which is negatively influenced by extensive pre-treatment. As a result of this study we decided to limit TPV to a maximum of three times the patient's blood volume in autologous apheresis procedures at our center.