Large‐volume leukapheresis in pediatric patients: processing more blood diminishes the apparent magnitude of intra‐apheresis recruitment

Abstract

In larger (older) patients, from whom fewer blood volumes were collected, there is a trend toward intra-apheresis recruitment, although less than reported previously. In the smaller (younger) patients, from whom more blood volumes were collected, no trend was observed. Lack of (or submaximal) prior mobilization in previously reported studies may have facilitated intracollection recruitment. Alternatively, the larger number of blood volumes collected from the smaller (younger) patients may have masked intra-apheresis recruitment. The study documents the feasibility of large-volume, 4-hour leukapheresis in pediatric patients.

Large volume leukapheresis: Efficacy and safety of processing patient’s total blood volume six times

“…The optimal study design would be to compare products collected during the same procedure at different time, which was done in this study, and differences caused by interindividual variability were excluded. Studies of kinetics of PBSC enrichment during LVL showed variable results [3,[8][9][10][19][20][21][22][23][24][25][26][27][28][29][30][31], which could be consequence of difference in volumes of processed blood. Therefore, processed blood volume in our study was standardized and strictly related to the patient's TBV.…”

“…tolerance, and consistence with working hours of apheresis unit, quality control and cell processing laboratories. Time-consuming LVL raises an issue of patient's compliance, but previous studies showed that cooperation for prolonged apheresis procedure could be achieved even in pediatric patients [17,25,26].…”

Kinetics of standardized large volume leukapheresis (LVL) in patients do not show a recruitment phenomenon of peripheral blood progenitor cells (PBPC)

“…7,8,[15][16][17][18][19][20] Therefore, the standardization of processed blood volumes seems to be necessary to enable a better interindividual comparison. 26,27 Moreover, animal studies showed distinct changes of G-CSF blood levels and suggest the G-CSF administration 2 h before the start of LVL.…”

“…17,18 Moreover, recruitment of stem cells during LVL was demonstrated in older but not in younger pediatric patients. 19 Finally, a recent study showed different kinetics of PBPC collections during LVL between adults and pediatric patients without increasing time-dependent collection efficiencies for the pediatric patients. 20 However, the hypothesis of recruitment of progenitor cells caused by LVL has never been proved by comparison with a control group.…”

Trafficking of CD34+ cells into the peripheral circulation during collection of peripheral blood stem cells by apheresis

“…This clinical observation, as well as the demonstration of increased blood levels of HSC in studies involving humans and animals not treated with cytokines, [13][14][15][16] led some authors to suggest that CD34 ϩ cells are recruited into the peripheral blood as a consequence of the LVL procedure itself, 11,12 although other investigators reported an exhaustion of CD34 ϩ cells in the peripheral blood during or after LVL. 17 This study was designed to explore the kinetics of CD34 ϩ cell release from the bone marrow or other reservoirs during the apheresis procedure. Multiple samples of blood were obtained at intervals during the apheresis pro-cedure in order to calculate the quantity and rate that these cells were released and to determine if apheresis collection techniques affected the trafficking of these cells between marrow and peripheral blood.…”