We evaluated stem cell mobilization in 195 consecutive sibling donors who underwent a uniform mobilization regimen of granulocyte colony-stimulating factor (G-CSF) at 10 microg/kg/day divided into twice daily dosing. On day 5, peripheral blood (PB) CD34 cells/microL were measured immediately prior to peripheral blood stem cell (PBSC) apheresis. Failed mobilization was defined as <20 CD34 cells/microL on day 5. The median age was 52 years and 73 (37%) were 55 years or greater. Comorbid conditions by the Charlson Comorbidity Index (CCI) occurred in 13%, but only 3% had Karnofsky performance status (PS) <100%. Eight (4%) failed mobilization, defined as <20 CD34 cells/microL on day 5. Older age was associated with fewer CD34 cells/microL (P=.002). In addition, 6/73 (8.2%) older donors failed mobilization compared to 2/122 (1.6%) younger donors (P=.054). Comorbidity, sex, race, and donor weight did not influence mobilization. Although low PS was very uncommon, it was associated with reduced mobilization (P=.021), but not mobilization failure. A small fraction of older donors mobilize poorly, and this is not explained by standard measures of comorbidity or PS.

There are limited data on the effect of donor body mass index (BMI) on peripheral blood stem cell (PBSC) mobilization response to granulocyte colony-stimulating factor (G-CSF), especially in unrelated donors. Obesity has been associated with persistent leukocytosis, elevated circulating progenitor cells, and enhanced stem cell mobilization. Therefore, we hypothesized that adequate collection of CD34+ cells may be achieved with lower doses (per kilogram of body weight) of G-CSF in donors with higher BMI compared with donors with lower BMI. Using the Center for International Blood and Marrow Transplant Research database, we evaluated the impact of donor BMI on G-CSF–mobilized PBSC yield in healthy unrelated donors. We examined 20 884 PBSC donations collected at National Marrow Donor Program centers between 2006 and 2016. We found significantly higher collection yields in obese and severely obese donors compared with normal and overweight donors. An increase in average daily G-CSF dose was associated with an increase in stem cell yield in donors with normal or overweight BMI. In contrast, an increase in average daily G-CSF dose beyond 780 μg per day in obese and 900 μg per day in severely obese donors did not increase cell yield. Pain and toxicities were assessed at baseline, during G-CSF administration, and postcollection. Obesity was associated with higher levels of self-reported donation-related pain and toxicities in the pericollection and early postdonation recovery periods. This study suggests a maximum effective G-CSF dose for PBSC mobilization in obese and severely obese donors, beyond which higher doses of G-CSF add no increased yield.

Bone marrow (BM) is an essential source of hematopoietic stem cell grafts for many allogeneic hematopoietic cell transplant (HCT) recipients, including adult patients (for specific diseases and transplantation strategies) and the majority of pediatric recipient. However, since the advent of granulocyte colony-stimulating factor-mobilized peripheral blood stem cell (PBSC) grafts, there has been a significant decrease in the use of BM in HCT, thought to be due mainly to the increased logistical challenges in harvesting BM compared with PBSCs, as well as generally no significant survival advantage of BM over PBSCs. The decreased frequency of collection has the potential to impact the quality of BM harvests. In this study, we examined >15,000 BM donations collected at National Marrow Donor Program centers between 1994 and 2016 and found a significant decline in the quality of BM products, as defined by the concentration of total nucleated cells (TNCs). The mean TNC concentration in BM donations dropped from 21.8 £ 10 6 cells/mL in the earliest era (1994 to 1996) to 18.7 £ 10 6 cells/mL in the most recent era (2012 to 2016) (means ratio, .83; P < .001). This decline in BM quality was seen despite the selection of more donors perceived to be optimal (eg, younger and male). Multivariate regression analysis showed that highervolume centers (performing >30 collections per era) had better-quality harvests with higher concentrations of TNCs collected. In conclusion, we have identified a significant decrease in the quality of BM collections over time, and lower-volume collection centers had poorer-quality harvests. In this analysis, we could not elucidate the direct cause for this finding, suggesting the need for further studies to investigate the key factors responsible and to explore the impact on transplant recipients.

BACKGROUND In a recent study, we determined that 30% of frequent plateletpheresis donors collected using the Trima Accel Automated Blood Collection System (Terumo BCT) had a CD4+ T‐cell count below 200 cells/μL. Whether CD4+ T‐cell lymphopenia is associated with donation using other plateletpheresis instruments is unknown. STUDY DESIGN AND METHODS We obtained blood samples from 30 current frequent Fenwal Amicus plateletpheresis donors. All participants had made 20 to 24 plateletpheresis donations in the most recent 365‐day period, and all had previously donated over 50 times on the Fenwal Amicus instrument. Blood samples were analyzed to determine blood counts, including CD4+ and CD8+ counts. RESULTS Of 30 study participants, none had a CD4+ count below 200 cells/μL. There was one participant with a CD4+ count between 200 and 300 cells/μL. This individual was over the age of 55 and had a history of more than 300 lifetime plateletpheresis sessions. One participant had a CD8+ count below the lower limit of normal (125 cells/μL) and a normal CD4+ count. CONCLUSION We did not detect severe CD4+ lymphopenia in frequent platelet donors undergoing plateletpheresis with the Fenwal Amicus. Since the Fenwal Amicus does not incorporate a leukoreduction system chamber, this finding supports the hypothesis that such chambers—found in the Trima Accel instrument—contribute to CD4+ lymphopenia in frequent platelet donors.

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