Cesarean section due to fetal distress increases the number of stem cells in umbilical cord blood

BACKGROUND: Umbilical cord blood (UCB) can be used as hematopoietic stem cell source for transplantation. The success of a transplantation is highly correlated with the number of total nucleated cells (TNCs) and CD34+ cells in the UCB. Certain obstetric factors increase the yield of stem cells in the UCB. It is necessary to evaluate optimal conditions in labor to decrease the rate of sample rejection due to low cell count. No data exist regarding the difference between primary and secondary Cesarean sections in terms of efficacy of stem cell harvesting. STUDY DESIGN AND METHODS: Seventy-nine consecutive UCB units from women who had a Cesarean section between 1997 and 2003 were included. The number of TNCs, CD34+ cells, colony-forming units (CFUs), white blood cells (WBCs), nucleated red blood cells (NRBCs), and the total collection volume were compared between cases with primary and secondary Cesarean section. RESULTS: UCB obtained after a Cesarean section due to fetal distress has significantly higher numbers of TNCs, CD34+ cells, NRBCs, and WBCs compared to elective Cesarean section. Of the cases with secondary Cesarean section due to fetal distress, 67 percent resulted in UCB units with sufficient TNC numbers (> or =80 x 10(7) TNCs) compared to 42 percent of the cases with primary Cesarean section. CONCLUSION: Fetal distress increases the number of hematopoietic stem cells mobilized into UCB. Particular effort should be made to collect UCB from newborns who experienced fetal distress.     

Consistency of the initial cell acquisition procedure is critical to the standardization of CD34+ cell enumeration by flow cytometry: results of a pairwise analysis of umbilical cord blood units and cryopreserved aliquots

BACKGROUND: The CD34+ cell content is a predictive factor for engraftment and survival after umbilical cord blood (UCB) transplantation. The high variability in the CD34 assay results in different recommended cell doses for infusion across transplant centers and also limits the clinical utility of the CD34+ cell counts provided by cord blood banks (CBBs). This bi-institutional study was intended to understand the sources of this variability.
STUDY DESIGN AND METHODS: The level of CD34 agreement between the University of Minnesota (UM) and the Madrid CBB (MCBB) was evaluated on 50 UCB units before and after cryopreservation. Two cryopreserved vials per unit were thawed and processed at both laboratories. Dual-platform ISHAGE-based flow cytometry was used for CD34 enumeration.
RESULTS: Postthaw nucleated cell recoveries were similar. However, whereas CD34+ cell enumeration before freezing was 0.35 ± 0.22 percent, the results after thawing were 0.98 ± 0.65 and 0.57 ± 0.39 percent at UM and MCBB, respectively. Bland-Altman plots analysis ruled out the interchangeability of MCBB and UM CD34 values. Differences in the initial cell acquisition settings accounted for most of the CD34 discrepancy, which was no longer present after normalization of the forward scatter threshold for cell acquisition.
CONCLUSIONS: The standardization of CD34+ cell enumeration by flow cytometry is strongly reliant on a consistent initial cell acquisition procedure. The interlaboratory variation can be minimized by using frozen cell aliquots as reference samples. Both requisites should be considered for CD34 testing and UCB unit selection by regulatory institutions involved with cord blood banking and transplantation.     

Increased numbers of total nucleated and CD34+ cells in blood group O cord blood: an analysis of neonatal innate factors in the Korean population

BACKGROUND: We analyzed neonatal factors that could affect hematopoietic variables of cord blood (CB) donated from Korean neonates. STUDY DESIGN AND METHODS: The numbers of total nucleated cells (TNCs), CD34+ cells, and CD34+ cells/TNCs of CB in neonates were compared according to sex, gestational age, birth weight, birth weight centile for gestational age, and ABO blood group. RESULTS: With 11,098 CB units analyzed, blood group O CB showed an increased number of TNCs, CD34+ cells, and CD34+ cells/TNCs compared with other blood groups. Although TNC counts were lower in males, no difference in the number of CD34+ cells was demonstrated because the number of CD34+ cells/TNCs was higher in males. An increase in the gestational age resulted in an increase in the number of TNCs and decreases in the number of CD34+ cells and CD34+ cells/TNCs. The numbers of TNCs, CD34+ cells, and CD34+ cells/TNCs increased according to increased birth weight centile as well as birth weight. CONCLUSION: CB with blood group O has unique hematologic variables in this large‐scale analysis of Korean neonates, although the impact on the storage policies of CB banks or the clinical outcome of transplantation remains to be determined.     

供者特征对脐带血造血功能的影响

目的 分析可能影响脐带血造血功能的供者特征.方法 对广州脐带血库1998年6月至2008年12月保存的4 358份脐带血的供者特征(包括母亲年龄、分娩方式、妊娠期、婴儿体重、婴儿性别)和脐带血采集量及造血功能的指标(包括总有核细胞数、CD34+细胞、干细胞集落等)进行相关性分析.结果 婴儿体重、分娩方式及婴儿性别是影响脐带血采集量、总有核细胞数、CD34+细胞数、CFUs及CFU-GM的主要因素.随着婴儿体重的增加,脐带血采集量、总有核细胞数、CD34+细胞数、CFUs、CFU-GM均呈上升趋势(P=0.000).阴道分娩时脐带血的采集量虽然低于刮宫产(P=0.000),但总有核细胞数、CD34+细胞数、CFUs,CFU-GM均高于剖宫产(P=0.000).女婴脐带血中总有核细胞数含量高于男婴(P=0.000),但脐带血采集量(P=0.000)、CD34+细胞数(P=0.002)均低于男婴.随着妊娠期的延长,脐带血中总有核细胞数增加(P=0.000),但CD34+细胞数减少(P=0.001).结论 某些脐带血供者特征对脐带血造血功能指标有积极影响.     

深低温冻存不同时间对脐血细胞质量的影响

本研究旨在探讨不同冻存时间的脐血干细胞复苏后的回收率,并分析冷冻复苏的细胞对患者植入速度的影响。20份经-196℃液氮低温保存1-10年的脐血干细胞标本,比较冻存前（脐血库提供资料）和复苏后的细胞活率、总有核细胞数（TNC）、CD34＋细胞和粒-巨噬细胞集落形成单位（CFU-GM）的数量,并分析复苏后的细胞回收对移植受者植入速度的影响。结果表明,不同冻存时间对复苏后干细胞的回收率没有影响。经冻存复苏后,细胞活存率为（92．75±2．55）％,TNC、CD34＋细胞数和CFU-GM的回收率分别为89．9％、84．8％和84．3％,与冻存前相比明显减少（P=0．000）,但细胞数量的下降对移植患者中性粒细胞和血小板的植入时间均无影响。冻存后TNC和CD34＋细胞数量与冻存前数量有很大的相关性（r=0．954;r=0．931,P=0．000）,而CFU-GM的相关性弱（r=0．285,P=0．223）。结论：冻存和复温过程会-定程度上损伤脐血干细胞,导致细胞丢失,但不会影响移植的效果。     

脐带血重建造血潜能的母体及新生儿因素分析

脐带血作为一种备选的移植用造血干细胞,能否成功植入与输入受者体内的总有核细胞（total nucleated cells,TNC）数、CD34＋细胞数及粒-巨噬细胞集落形成单位（colony-forming unit-granulocyte-macrophage,CFU-GM）有关。本研究探讨影响脐带血造血潜能的母体及新生儿因素。按照广州脐血库标准化操作常规（SOP）,对脐带血样本进行筛选、处理、检测及冷冻,回顾性分析已保存的4615份脐带血样本的造血细胞参数及其与母体及新生儿特征的相关性。结果表明：脐带血采集量（Mean±SD：95.23±22.42ml;Median：91.85ml）与处理前TNC[Mean±SD：（1.34±0.49）×109;Median：1.25×109]及处理后TNC[Mean±SD：（1.21±0.42）×109;Median：1.14×109]、CD34＋细胞数[Mean±SD：（5.14±4.55）×106;Median：4.08×106]、CFU-GM[Mean±SD：（9.72±8.66）×105;Median：7.53×105]三者均显著相关（p〈0.001）。在供者因素中,只有婴儿出生体重与脐带血采集量及造血细胞参数均呈显著正相关（p〈0.001）,较大婴儿的脐带血在采集量、TNC、CD34＋细胞数及CFU-GM方面均呈现优势（p〈0.001）。母亲年龄与上述各项参数均无显著相关。孕龄与处理前/后TNC正相关（p〈0.001;p〈0.001）,与CD34＋细胞数呈负相关（p=0.04）,而与采集量及CFU-GM均无显著相关。剖宫产时采集的脐带血量虽然高于阴道分娩（Mean±SD：97.05ml±22.23mlvs.92.53ml±22.43ml;Median：94.08mlvs.88.82ml;p〈0.001）,但各细胞参数均低于阴道分娩（p〈0.001）。男婴脐带血的采集量和CD34＋细胞数高于女婴（Mean±SD：96.41ml±22.31mlvs.93.95ml±22.47ml;Median：93.27mlvs.90.14ml;p〈0.001）;[Mean±SD：（5.28±5.04）×106vs.（5.00±3.94）×106;Median：4.18×106vs.3.94×106;p=0.042]、但处理前TNC及处理后TNC均低于女婴[Mean±SD：（1.31±0.50）×109vs.（1.37±0.47）×109;Median：1.22×109vs.1.28×109;p〈0.001];[Mean±SD：（1.18±0.42）×109vs.（1.24±0.41）×109;Median：1.10×109vs.1.17×109;p〈0.001],二者CFU-GM的差异无统计学意义。结论：本研究数据有助于优化脐带血供者筛选及提高脐血库资源利用率。脐血库应侧重选择体重较大、阴道分娩的新生儿供者,优先处理采集量大、TNC高的脐带血样本。     

Analysis of maternal and neonatal factors that influence the nucleated and CD34+ cell yield for cord blood banking

BACKGROUND: It would be beneficial to be able to predict the cord blood (CB) cell yield from volunteer donors before cell processing. STUDY DESIGN AND METHODS: The maternal and neonatal factors that influence the total nucleated cell (TNC), CD34+ cell, and CFU-GM yields in CB collected for the Chugoku-Shikoku Cord Blood Bank were evaluated. RESULTS: In a univariate analysis, the volume of CB collected was significantly correlated with the TNC, CD34+ cell, and CFU-GM yields (p < 0.001). A longer cord (p < 0.001), larger placenta (p < 0.001), and bigger baby (p < 0.001) were associated with a greater volume of CB. A female baby (p < 0.05) and longer gestational age (p < 0.005) were associated with a higher TNC concentration. A younger maternal age (p < 0.05), larger birth weight (p < 0.001), shorter gestational age (p < 0.001), and shorter time from collection to processing (p < 0.05) were associated with a higher CD34+ cell concentration. A multivariate linear regression analysis was performed to predict the yield and determine first-level selection criteria to start processing when the volume of CB units was on the borderline. However, this formula might not be suitable for actual use. CONCLUSION: Maternal and neonatal factors appeared to affect CB cell yields. These findings might be useful for efficiently collecting more qualified CB units.     

Factors affecting banking quality of umbilical cord blood for transplantation

BACKGROUND: The most important objective for cord blood banks is to store cord blood units of high quality, which is determined by total nucleated cells (TNCs) and CD34+ cells. Determining the factors affecting the stored life‐saving cells would be beneficial to the field. STUDY DESIGN AND METHODS: A total of 4930 cord blood units were collected between January 2007 and October 2009 and processed using a double extraction technique to sediment red blood cells with variable centrifugation time determined by the formula CT = KL – M, where CT is centrifuge time, K is 7.7227, M is 29.742, and L is ln (volume of cord blood with anticoagulant). The recovery rate of TNCs and other relevant factors affecting banking quality were analyzed. RESULTS: The mean recovery rate of TNCs was 97.7 ± 2.5% with 0.04% (2/4930) units below 80% and 10.8% (532/4930) units below 95%. The TNCs per unit was affected by gestation duration (p < 0.01), sex of infant (p < 0.01), mode of delivery (p < 0.01), collection method (p < 0.01), and ethnicity (p < 0.001). The number of postprocessing CD34+ cells was affected only by sex of the infant (p < 0.05). The viability of nucleated cells after processing was 94.8 ± 4.8% and was affected by the number of hours between collection and processing (p < 0.01). In contrast, the viability of CD34+ cells was 99.5 ± 1.0% (n = 30) when samples with low viability of TNCs were assessed. The results did not reveal a significant correlation (r = 0.07, p = 0.38). CONCLUSION: The double extraction technique provides a high and consistent recovery of TNCs, which ensures that more life‐saving cells will be banked for transplants.     

Prospective flow cytometric evaluation of nucleated red blood cells in cord blood units and relationship with nucleated and CD34(+) cell quantification

BACKGROUND: Cord blood (CB) represents an alternate source of stem cells in transplantation. Nucleated red blood cells (NRBCs) are a physiological subset of CB population. Although it is important to have an accurate estimate of CD34(+) cell number, NRBCs could compromise white blood cell count and interfere with CD34(+) cell quantification. STUDY DESIGN AND METHODS: A total of 826 CB units were analyzed for total nucleated cells (TNCs), NRBCs, and CD34(+) cells by flow cytometry. NRBCs were also counted conventionally by manual microscopy. Percentages of CD34(+) cells corrected by NRBC count (CD34+c) were determined as follows: %CD34+c = CD34(+)/CD45(+) (x10(6))/(TNCs (x10(8)) - NRBCs (x10(8))). RESULTS: The mean percentages of CD34+ cells and NRBCs were 0.27 percent (range, 0.01%-1.25%) and 7.64 percent (range, 0.13%-84%), respectively. Comparison between flow cytometric and microscopic NRBC count showed a regression of y = 0.685 + 0.719x and a coefficient of determination of r(2) = 0.721. When corrected with NRBC count, the mean percentage of CD34(+) c cells was 0.295 percent (p = 0.0008 compared with CD34(+)%) and mean TNCc count was 14.8 x 10(8) (p < 10(-4) compared to TNC count). CONCLUSION: The determination of NRBCs with a flow cytometric method might represent a new strategy for providing satisfactory quality assurance controls of CB products.     

固定抗凝剂量加入不同量脐血后脐血质量分析评估的研究

目的:研究固定抗凝剂量加入不同量脐血后对脐血质量的影响.方法:对6060份脐血样本,按照抗凝剂/脐血体积比分为28:(10-29)ml组、28:(30-69)ml组、28:(70-109)ml组、28:(110-150)ml组和28:(＞150)ml组.分析各组脐血的冻前有核细胞数、有核细胞活性、CFU-GM数量、CD...     

Mobilization kinetics of CD133+ hematoprogenitor cells for hematopoietic grafting

BACKGROUND: Quantification of CD34+ mononuclear cells is the most important quality control measure for hematopoietic stem cell (HSC) transplantation. A fraction of CD34+ cells also express the CD133 antigen. These cells constitute a group of earlier, less-differentiated HSCs with a potentially higher capacity for engraftment. The correlation between total CD34+ peripheral HSCs and the fraction of these cells that coexpress CD133 was determined before and after automated collection by leukapheresis, as well as the effect of HSC CD133+ dose on hematopoiesis recovery.
STUDY DESIGN AND METHODS: Granulocyte–colony-stimulating factor mobilization of HSCs from the marrow to the peripheral blood (PB) of allogeneic and autologous donors was followed by automated collection through leukapheresis on the fifth day. Quantification of CD34+ and CD133+ cells was performed on PB before collection and in the hematopoietic graft (HG) by flow cytometry.
RESULTS: There was a significant correlation between CD133+ and CD34+ HSCs in the PB before collection and in the final product for grafting (r = 0.62 and 0.64; p < 0.01). CD34+ HSCs per µL in PB and the HG was the only variable that did not correlate (r = 0.18). CD34+/CD133+ correlation increased from 0.33 on PB to 0.94 on the leukapheresis product (p < 0.01). Time to recovery was not related to CD133+ HSCs infused.
CONCLUSION: There was a significant correlation of both number per µL and percentage of CD34+/CD133+ HSCs before and after collection for transplantation; number of CD133+ cells had no apparent clinical impact on time to hematopoiesis regeneration.     

Red blood cell depletion with a semiautomated system or hydroxyethyl starch sedimentation for routine cord blood banking: a comparative study

BACKGROUND: The major problem with long-term cord blood (CB) banking is the required storage space. In this sense, many studies have been performed to establish techniques for volume reduction of CB units. STUDY DESIGN AND METHODS: We compared two different methods for CB volume reduction in both development and routine phases: hydroxyethyl starch (HES) sedimentation and top-and-bottom fractionation with the Optipress II (Baxter Healthcare). Monitoring the total nucleated cell (TNC) count, lymphocytes, CD34+ cells, and colony-forming unit (CFU) content in both preprocess and postprocess CB units assessed the volume reduction process. RESULTS: The CB units processed in both groups had comparable volume and cells counts before and after volume reduction, except for number of red blood cells (RBCs), which was significantly greater for the Optipress II group. Recoveries of CD34+ and RBC depletion were significantly better for the HES group. For routine processing, TNC and lymphocyte recoveries were significantly better for CB units processed by the Optipress II system. There was, however, significantly less depletion of RBCs for this group. The time required for CB processing with the Optipress II was significantly shorter than the time needed for volume reduction by addition of HES (25+/-5 min vs. 55+/-10 min). CONCLUSION: The volume reduction method with the Optipress II is a closed time-saving system that allows good cell recoveries. In contrast, the main advantage of the HES method is the higher RBC depletion that influences CFU content. Reducing RBC content must be the object of further improvements for volume reduction using the Optipress II method.     

Impact of donor- and collection-related variables on product quality in ex utero cord blood banking

BACKGROUND: Optimizing product quality is a current focus in cord blood banking. This study evaluates the role of selected donor- and collection-related variables. STUDY DESIGN AND METHODS: Retrospective review was performed of cord blood units (CBUs) collected ex utero between February 1, 2000, and February 28, 2002. Preprocessing volume and total nucleated cell (TNC) counts and postprocessing CD34 cell counts were used as product quality indicators. RESULTS: Of 2084 CBUs, volume determinations and TNC counts were performed on 1628 and CD34+ counts on 1124 CBUs. Mean volume and TNC and CD34+ counts were 85.2 mL, 118.9 x 10(7), and 5.2 x 10(6), respectively. In univariate analysis, placental weight of greater than 500 g and meconium in amniotic fluid correlated with better volume and TNC and CD34+ counts. Greater than 40 weeks' gestation predicted enhanced volume and TNC count. Cesarean section, two- versus one-person collection, and not greater than 5 minutes between placental delivery and collection produced superior volume. Increased TNC count was also seen in Caucasian women, primigravidae, female newborns, and collection duration of more than 5 minutes. A time between delivery of newborn and placenta of not greater than 10 minutes predicted better volume and CD34+ count. By regression analysis, collection within not greater than 5 minutes of placental delivery produced superior volume and TNC count. CONCLUSION: Donor selection and collection technique modifications may improve product quality. TNC count appears to be more affected by different variables than CD34+ count.     

Cord Blood Banking and Transplantation in China: A Ten Years Experience of a Single Public Bank

Background

Umbilical cord blood (UCB) has successfully used for transplantation to treat hematologic malignancies and genetic diseases. Herein, we describe the experience generated in a single public UCB bank at Zhejiang Province in China.

Methods

Good manufacturing practice and standard operating procedures were used to address donor selection as well as UCB collection, processing, and cryopreservation. Total nucleated cells (TNCs), cellular viability, CD34+ cells, and colony-forming units were determined, and infectious diseases screening test, sterility test, and HLA typing for UCB units were done.

Results

Only 18.51% of all collected UCB units met storage criteria, and 7,056 UCB units were cryopreserved in 10 years. The volume of UCB units was 95.0 ± 22.0 ml. The number of TNCs before and after processing was 13.32 ± 3.63 × 10⁸ and 10.63 ± 2.80 × 10⁸, respectively, and the recovery rate was 80.71 ± 11.26%. 0.4344 ± 0.1874% of the TNCs were CD34+ cells. The CFU-GM was 32.1 ± 28.0 colonies per 1 × 10⁵ nucleated cells. Based mainly on HLA and nucleated cell content, 26 UCB units were released for transplantation.

Conclusions

A public UCB bank was successfully established in China; collection and processing of UCB units should be optimized in order to gain maximum volume and cell count.     

Increased Nucleated RBCs in Cord Blood: Not an Exclusion Criterion but a Quality Indicator for Hematopoietic Progenitor Cell Transplantation

Increased nucleated red blood cell (NRBC) counts have been reported to be associated with adverse fetal outcomes, and cord blood units (CBUs) with increased NRBC counts require a 2^nd questionnaire to determine their suitability for transplantation. However, a recent study demonstrated a positive correlation of NRBCs with CD34⁺ cells and total nucleated cells (TNCs). We evaluated the association between the NRBC count and hematopoietic progenitor cell (HPC) content (TNC and CD34⁺ cell counts) in Korean full-term newborn CBUs. In addition, we assessed whether an increased NRBC count is associated with newborn health problems that impair CBU safety. Among the 32,876 units processed from May 2006 to December 2018, a total of 23,385 CBUs with a TNC count ≥ 7 × 10⁸ and reliable perinatal information were analyzed to assess the association of the NRBC count with CBU parameters, and the newborns associated with 457 CBUs that required the 2^nd questionnaire due to an increased NRBC (≥ 15 NRBCs/100 WBCs) were assessed at one year for health problems that threatened CBU safety. The majority of the CBUs that required the 2^nd questionnaire due to an increased NRBC count (96.9%) were determined to be suitable for transplantation. Those with an increased NRBC count showed significantly higher CD34⁺ cell and TNC counts and a higher rate of transplantation (P < 0.001, < 0.001 and 0.025, respectively). NRBCs showed a significant positive correlation with TNCs and CD34⁺ cells and a significant negative correlation with birth weight (all P < 0.001; adjusted r = 0.185, 0.369 and - 0.029, respectively). In the multiple linear regression analysis, NRBCs showed independent and positive correlations with TNCs and CD34⁺ cells after adjustments for birth weight and gestational age (all P < 0.001; β = 0.182, adjusted R² = 0.053 and β = 0.367, adjusted R² = 0.418). An increased NRBC count in full-term normal delivery is a surrogate marker of HPCs in CBUs rather than an exclusion criterion for CBU safety. Moreover, providing the NRBC count together with the NRBC-corrected TNC count will be useful for clinicians to select CBUs for transplantation.     

Associations among birth weight, placental weight, gestational period and product quality indicators of umbilical cord blood units

Introduction

Numbers of CD34+ cell and total nucleated cell (TNC) and cord blood volume are commonly used as indicators for haematopoietic potential of umbilical cord blood (UCB) units. The purpose of this study was to investigate the relationship between donor-related factors and the quality indicators of UCB.

Methods

Obstetric and neonatal clinical laboratory data of a total of 1549 UCB units were obtained from Buddhist Tzu Chi Stem Cells Center (BTCSCC) Cord Blood Bank. A retrospective multivariate analysis was conducted to analyze the data.

Results

Our results showed that birth weight had positive correlations with each of the clinical features of CD34+ cell number, TNC count and unit volume of UCB, followed by the placental weight. Longer gestational period would decrease CD34+ cell number and volume of UCB. Female baby and mode of vaginal delivery of neonates were found to have larger amount of TNC in UCB.

Conclusion

Our results would be helpful and beneficial in building up standard criteria for evaluating stored UCB units.     

脐血复温后细胞输入剂量对植入的预测作用分析

本研究探讨非血缘供者脐带血移植(unrelated cord blood transplantation,UCBT)中复温后供者细胞输入剂量对植入和造血重建的预测作用。回顾性分析1999年8月至2010年4月间接受单份UCBT的97例儿童恶性及非恶性疾病患者的临床资料,比较冷冻前和复温后检测的总有核细胞(total nucleated cells,TNC)、CD34+细胞及粒-巨噬细胞集落形成单位(colony-forming unit-granulocyte-macrophage,CFU-GM)的输入剂量对受者的植入及造血重建速度的影响,供者脐带血均来自广州脐血库。结果表明,冷冻前TNC(/kg)(mean±SD:7.65×107±4.26×107;median:6.34×107)、CD34+细胞(/kg)(mean±SD:4.64×105±4.47×105;median:3.03×105)及CFU-GM(/kg)(mean±SD:0.79×105±1.09×105;median:0.57×105)与其对应的复温后TNC(/kg)(mean±SD:6.98×107±4.12×107;median:6.00×...     

CD34+ progenitors and colony-forming units-granulocyte macrophage are recruited during large-volume leukapheresis and concentrated by counterflow centrifugal elutriation

The recruitment of mononuclear cells (MNCs), colony-forming units- granulocyte macrophage (CFU-GM), lymphocyte subpopulations, and CD34+ progenitor cells was studied during large-volume (15-25 L blood processed) peripheral blood stem cell (PBSC) harvests. Normal donors (n = 13) underwent a 4-hour leukapheresis designed to maximize PBSC yield (blood flow rate, 85 mL/min). Mean (+/− SD) volume processed was 17.7 +/− 0.4 L, and yield was 2.4 +/− 0.7 × 10(10) white cells containing 99 percent MNCs and 1.3 mL red cells per L of blood processed. Postapheresis hematocrit, platelets, and MNCs were reduced from preapheresis values by 7, 35, and 23 percent, respectively (p < 0.05). In nine donors, the component was collected as four 1-hour samples, and culturing of CFU-GM and flow cytometric analysis of lymphocyte subpopulations and CD34+/HLA-DR+ cells were done in individual samples. Total CFU-GM were 2.4 +/− 1.4 × 10(6) (3.0 +/− 1.8 × 10(4) CFU-GM/kg) and lymphocytes were 20.8 × 10(9), with 75 percent CD3+ T cells, 10 percent CD19/CD20+ B cells, and 17 percent natural killer cells. A more than twofold increase in CFU-GM and CD34+ cells was noted over the course of the 4-hour procedure (p < 0.05). In four donors, the leukapheresis component underwent counterflow centrifugal elutriation (CCE), which separated it into four fractions in an attempt to concentrate CD34+ and CFU-GM progenitors and to deplete T-lymphocytes on a large scale. There was a 1.8-, 4.6-, 3.9-, and 0.32-fold increase in CFU-GM in the four fractions relative to the unseparated component.(ABSTRACT TRUNCATED AT 250 WORDS)