CD41+ and CD42+ hematopoietic progenitor cells may predict platelet engraftment after allogeneic peripheral blood stem cell transplantation

The objective of this study was to quantify subpopulations of CD34+ cells such as CD41+ and CD42+ cells that might represent megakaryocyte (MK) precursors in peripheral blood stem cell (PBSC) collections of normal, recombinant human granulocyte‐colony stimulating factor (rhG‐CSF) primed donors and to determine whether there is a statistical association between the dose infused megakaryocytic precursors and the time course of the platelet recovery following an allogeneic PBSC transplantation. Twenty‐six patients with various hematologic malignancies transplanted from their HLA identical siblings between July 1997 and December 1999 were used. All patients except one with severe aplastic anemia who had cyclophosphamide (CY) alone received busulfan‐CY as preparative regimen and cyclosporine‐methotrexate for GVHD prophylaxis. Normal healthy donors were given rhG‐CSF 10 μg/kg/day subcutaneously twice daily and PBSCs were collected on days 5 and 6. The median number of infused CD34+, CD41+ and CD42+ cells were 6.61 × 10⁶/kg (range 1.47–21.41), 54.85 × 10⁴/kg (5.38–204.19), and 49.86 × 10⁴/kg (6.82–430.10), respectively. Median days of ANC 0.5 × 10⁹/L and platelet 20 × 10⁹/L were 11.5 (range 9–15) and 13 (8–33), respectively. In this study, the number of CD41+ and CD42+ cells infused much better correlated than the number of CD34+ cells infused with the time to platelet recovery of 20 × 10⁹/L in 26 patients receiving an allogeneic match sibling PBSC transplantation (r = ?0.727 and P < 0.001 for CD41+ cells, r = ?0.806 and P < 0.001 for CD42+ cells, r = ?0.336 and P > 0.05 for CD34+ cells). There was an inverse correlation between the number of infused CD41+ and CD42+ cells and duration of platelet engraftment. Therefore, as the number of CD41+ and CD42+ cells increased, duration of platelet engraftment (time to reach platelet count of ≥ 20 × 10⁹/L) shortened significantly. Based on this data we may conclude that flow cytometric measurement of CD41+ and CD42+ progenitor cells may provide an accurate indication of platelet reconstitutive capacity of the allogeneic PBSC transplant. J. Clin. Apheresis. 16:67–73, 2001. © 2001 Wiley‐Liss, Inc.     

Identification of megakaryocyte precursors in peripheral blood stem cell collections from normal donors

Platelet engraftment, the time course and magnitude of platelet recovery (PR) post-transplant, is imprecisely defined but is most often reported as the time to transfusion (tx) independence and/or a platelet count ⩾20,000/μl. While correlations between engraftment time for granulocytes (PMN) and the dose of CD34-positive cells per kilogram are established, such associations have not been established for platelet engraftment. The objective of this study was to quantify subpopulations of CD34-positive cells in peripheral blood stem cell (PBSC) collections of normal, colony-stimulating factor-granulocyte) (G-CSF) primed donors that might represent megakaryocyte (MK) precursors, and to determine whether there is a statistical association between the dose transfused and the time course of the recovery. Based on previously published data of the sequential expression of CD34, HLA-DR, and CD61, among others, during MK maturation, a combination of corresponding antibodies for the detection of various antigen coexpressions by flow cytometry fluorescence-activated cell sorting [FACS] was chosen. CD34-positive cells were further subdivided into CD34++ (bright) and + (dim). Ploidy of density-gradient separated cells was examined in subsequent donor samples by FACS. For the entire group of patients, there was no strong correlation between any of the studied subpopulations and time to PR. Only in a selected groups of patients whose platelet counts showed a sustained increase during the first 6 days after engraftment, there was a weak correlation between the time to PR and the quantity of CD34+/+CD61+ (r = −0.57) and CD34++HLA-DR-CD61+ (r = −0.62) cells infused. The magnitude of platelet production in these pt., a product of the peripheral blood platelet count and the patient's blood volume, was correlated with the time to PR (r = −0.73). We conclude from this study that subpopulations within CD34+ cells are making some contribution to PR in allogeneic peripheral blood stem cell transplantation, but the correlations are not sufficiently strong because there are probably too many unpredictable and unknown variables in the allogeneic setting that influence the pattern of engraftment. J. Clin. Apheresis 13:7–15, 1998. © 1998 Wiley-Liss, Inc.     

Peripheral blood stem cell apheresis for allogeneic transplants: Ibni Sina experience

BACKGROUND: The rate of utilizing peripheral blood stem cells (PBSC) as a source for allogeneic stem cells is growing rapidly. We aimed to demonstrate our 4 years experience as the largest apheresis center in Turkey and analyzed the content of the apheresis material. PATIENTS AND METHODS: From 1998 to the end of April 2002, 151 leukopheresis procedures were performed on 116 healthy donors (M/F:66/50) with a median age of 30 years (14-53). The HLA identical sibling donors received rhG-CSF 10 microg/kg/day sc. for 4 days and at the 5th day leukopheresis was started until collecting >4 x 10e6/kg CD34+ cells. Two times the donors' total blood volume was processed in 195 min (178-245) on continuous flow cell separators using peripheral venous access. RESULTS: Preapheresis WBC was 51.5 x 10e9/L (range, 13.11-91.3). Mono nuclear cell, CD34 and CD3 quantity of the harvest material were 5.35 x 10e8/kg (range, 0.45-23.46), 6.4 x 10e6/kg (range, 2.49-33.27) and 2.79 x 10e8/kg (range, 0.46-30.95), respectively. We were able to reach the target CD34 count after 1st cycle in 39% and 2nd cycle 61% of the procedures. In all donors with a peripheral blood CD34 count >80/mcl we succeeded to collect enough stem cells with only one leukopheresis. CONCLUSION: Collection of peripheral blood stem cells with continuous flow cell separators is well tolerated, with no mobilization failures or poor mobilizers. We collected high values of CD34+ cells (med. 6.4 x 10e6/kg) at the expense of high CD3+lymphocytes (med. 2.79 x 10e8/kg), which may increase the risk of acute and chronic GVHD after allogeneic hemapoietic cell transplantation.     

Critical issues on high-dose chemotherapy with autologous hematopoietic progenitor cell transplantation in breast cancer patients

Introduction: High-dose chemotherapy (HDC) with autologous hematopoietic progenitor cell transplantation (AHPCT) for high-risk (HR) or metastatic breast cancer (MBC) is no longer an option.

Areas covered: An expert panel including medical oncologists and hematologists produce an opinion paper on the use of HDC and AHPCT in BC patients and they explain why they believe that; despite inconclusive results thus far, this treatment should have an ongoing role in breast cancer management under clinical trials.

Expert opinion: HDC with AHPCT has become a safe treatment modality and an advantage in disease-free survival has been observed in most of the studies with HDC, with the caveat that today, even a limited relapse-free survival and progression-free survival benefit is sufficient for the approval of new antineoplastic agents. Moreover, in HRBC, an overall survival benefit by HDC could be achieved in the HER2-ve and triple-negative populations and, in this setting, HDC with AHPCT represents a therapeutic option that can be proposed to well-informed patients. In MBC, the HDC approach should be investigated further in selected patients with HER2-ve, chemosensitive disease. This paper is not intended to give any conclusion, but rather to open a debate on the value of HDC in HR and MBC.     

A simple automatized audit system for following and managing practices of platelet and plasma transfusions in a neonatal intensive care unit

During neonatal intensive care, blood components are often used in clinical situations where both their efficacy and safety lack solid justification. A practical system to continuously analyse actual transfusion practices is a prerequisite for improvements of quality in transfusion therapy. We hypothesized that such a system would reveal inappropriate variations in clinical decision making and offer a means for staff education and quality improvement and assurance. The study consisted of three 120-152-day periods (P I, P II and P III) between January 2000 and October 2001 and involved 543 new patient admissions (141 patients with birth weight < 1501 g) and 6227 days of patient care at a single tertiary level NICU. P I was a control with no intervention, P II was after technically introducing the computer system and, the last period, P III was after presenting and discussing the results of P I and P II at a staff meeting. Upon an order of platelet or fresh frozen plasma (FFP) unit from the blood bank, a computer-based audit system compared the last platelet count or prothrombin time [expressed as percentage of normal clotting activity, prothrombin time (PT-%)] to predefined criteria. In the case of exceeding the preset thresholds, the system required additional information and recorded the pretransfusion laboratory values for later analysis. Thirty-two per cent of platelet transfusions were given with pretransfusion platelet count >49 x 10(9) L(-1), and 60% of these transfusions (19% of all platelet transfusions) could not be clinically justified in retrospective chart review. There was no significant change in this practice from P II to P III. FFP transfusions were given with significantly different pretransfusion PT-% values during P II and P III. The proportions of FFP transfusions with pretransfusion PT-% > 49% were 7.8% and 0.9% during P II and P III, respectively (P < 0.0001). In chart review, none of the FFP transfusions with pretransfusion PT-% > 49% could be justified by clinical grounds. Inappropriate transfusions of both platelets and plasma remain a significant challenge for quality assurance of neonatal intensive care. Automated recording of pretransfusion platelet count and prothrombin time reliably identified the poorly justified transfusions and thus offered a practical resource-saving tool for quality assurance of transfusion in the NICU. A significant shift towards more appropriate use of plasma was demonstrated after implementation of the audit system.     

Peripheral blood hematopoietic stem cell mobilization and collection efficacy is not an independent prognostic factor for autologous stem cell transplantation

BACKGROUND: The successful mobilization and collection of hematopoietic stem cells are dependent on a number of clinical factors such as previous chemotherapy and disease stage. The aim of this retrospective study was to determine whether the effectiveness of mobilization and collection is an independent prognostic factor for autologous stem cell transplantation outcome. STUDY DESIGN AND METHODS: A total of 358 patients who received transplants from January 2003 to December 2004 (201 male and 157 female patients, ages from 2.7 to 77.3 years with median of 53 years of age) underwent autologous hematopoietic stem cell collection after mobilization with granulocyte-colony-stimulating factor (G-CSF) or G-CSF plus chemotherapy priming. This retrospective study included patients with diagnoses of acute myelogenous leukemia, non-Hodgkin's lymphoma, Hodgkin's disease, multiple myeloma, and solid tumors. All patients underwent stem cell collection until a target or a minimum CD34+ cell dose was reached. Correlations were performed between stem cell mobilization and/or collection efficacy and transplantation outcomes. RESULTS: In general, both larger reinfused CD34+ cell dose and shorter number of days for the stem cell count to reach the minimum of 2 x 10(6) per kg CD34+ cells do not foster quicker engraftment. Reinfused CD34+ cell dose of less than 12 x 10(6) and number of days stem cell collection to reach this minimum CD34+ cell dose did not independently affect the overall survival (OS) or disease-free survival (DFS). CONCLUSION: The effectiveness of hematopoietic stem cell mobilization and collection as defined as number of days to reach a CD34+ cell dose of 2 x 10(6) per kg should not be used independently to forecast posttransplantation prognosis, engraftment, DFS, and OS.     

单采血小板前后献血者血清甲状旁腺素及电解质的变化

目的观察单采血小板前后献血者血清甲状旁腺素及电解质浓度的变化。方法选择单采血小板献血者45名,分为补钙组(n=11)和未补钙组(n=34),分别检测血小板采集前后血清甲状旁腺素(PTH)和钙、磷、钾、钠、镁离子浓度;献全血组(n=24)。结果单采后补钙组PTH浓度有统计学意义(t=2.472,P<0.05),未补钙组单采后磷浓度升高(t=3.191,P<0.05);单采血小板献血者采前血清磷、钙、钠的浓度低于对照组(t值分别为2.477,2.349和2.064,P<0.05),但仍在正常范围内。结论单采血小板会引起献血者血钙浓度短暂降低,但机体可自身迅速调节,不必常规补钙;单采血小板献血者采集前血清磷、钙、钠的浓度低于全血献血者。     

Platelet storage lesion in interim platelet unit concentrates: A comparison with buffy-coat and apheresis concentrates

Platelet storage lesion is characterized by morphological changes and impaired platelet function. The collection method and storage medium may influence the magnitude of the storage lesion. The aim of this study was to compare the newly introduced interim platelet unit (IPU) platelet concentrates (PCs) (additive solution SSP+, 40% residual plasma content) with the more established buffy-coat PCs (SSP, 20% residual plasma content) and apheresis PCs (autologous plasma) in terms of platelet storage lesions. Thirty PCs (n = 10 for each type) were assessed by measuring metabolic parameters (lactate, glucose, and pH), platelet activation markers, and in vitro platelet aggregability on days 1, 4, and 7 after donation. The expression of platelet activation markers CD62p (P-selectin), CD63 (LAMP-3), and phosphatidylserine was measured using flow cytometry and in vitro aggregability was measured with multiple electrode aggregometry. Higher platelet activation and lower in vitro aggregability was observed in IPU than in buffy-coat PCs on day 1 after donation. In contrast, metabolic parameters, expression of platelet activation markers, and in vitro aggregability were better maintained in IPU than in buffy-coat PCs at the end of the storage period. Compared to apheresis PCs, IPU PCs had higher expression of activation markers and lower in vitro aggregability throughout storage. In conclusion, the results indicate that there are significant differences in platelet storage lesions between IPU, buffy-coat, and apheresis PCs. The quality of IPU PCs appears to be at least comparable to buffy-coat preparations. Further studies are required to distinguish the effect of the preparation methods from storage conditions.     

Peripheral blood stem cell collection for allogeneic hematopoietic stem cell transplantation: Practical implications after 200 consequent transplants

Background

Proper stem cell mobilization is one of the most important steps in hematopoietic stem cell transplantation (HSCT). The aim of this paper is to share our 6 years’ experience and provide practical clinical approaches particularly for stem cell mobilization and collection within the series of more than 200 successive allogeneic HSCT at our transplant center.

ABO血型不合的异基因造血干细胞采集及移植效果研究

本研究评价COBE Spectra血细胞分离机按干细胞采集程序采集HLA配型相合、ABO血型不合供者外周血造血干细胞的效能,观察未去除红细胞和(或)血浆进行异基因外周血干细胞移植的效果。应用COBE Spectra血细胞分离机的自动干细胞采集程序采集28例异基因供者外周血干细胞,并选用同期ABO血型相合15例作对照。检测采集物有核细胞(NC)数、单个核细胞(MNC)比例及CD34+细胞计数,观察造血功能重建情况和转变为供者血型所需要的时间。结果表明,ABO血型不合和相合组采集物中的NC、CD34+细胞数、MNC比例无统计学差异(p>0.05)。ABO血型不合组和相合组中性粒细胞和血小板恢复的时间无统计学差异(p>0.05)。14例ABO血型主要不合患者,红系造血明显延迟,ABO血型不合组28名患者于移植后35-193天血型成功转变为供者型,和ABO血型相合组相比均有统计学差异(p<0.01)。结论:ABO血型不合不是异基因造血干细胞移植的障碍,主要不合可能是红系造血明显延迟的主要原因。     

Peripheral blood stem cell collection: the interaction of technology, procedure, and biological factors

Centrifugal technology, continuous flow and discontinuous flow, has served as the technology platform for extracting cell concentrates of interest from peripheral blood (PB) for patient therapy for the past 35-40 yr. Models for procedure outcome exist for collection of normal donor (ND) platelet and granulocyte concentrates that integrate: (1) biological variables (pre-procedure PB cell concentration, the total circulating quantity of cells, donor/patient blood volume (BV)), (2) device efficiency, and (3) procedure parameters such as total blood processed (TBP), and in the case of cytoreductions - the volume collected. (cf. Hester J, Kellogg R, Mulzet A, et al., Blood (54) (1979) 254; Hester J, Ventura G, J Clin Apheresis (4) (1988) 188.) To date, no predictive CD34+ yield algorithm integrating these three variables has been formulated that could be applied prospectively for individual ND or patients (PT). There are economic, toxicity and statistical comparison benefits to be derived from generating such an algorithm.A small pilot study is presented with a brief review of current publications that suggest the circulating quantity of CD34+ cells available to be collected and the quantity mobilized during leukapheresis are the major contributing factors to CD34+ yield, somewhat obscuring the role of the total blood processed (TBP). Intraprocedure CD34+ cell mobilization, incompletely characterized to date, appears to be a dynamic nonlinear process, as the harvested yield does not rise proportionally as the fraction of BV processed increases. And, like the pre-procedure PB CD34+ concentration and total circulating quantity, CD34+ mobilization during leukapheresis probably relates to prior treatment and the priming regimen. Studies that provide: (1) separate analyses of PT populations divided according to chemotherapy toxicity factors; (2) design and implementation of optimal priming regimens with respect to dose 'intensity' of both growth factors and chemotherapy; and (3) standardization of laboratory assays of CD34+ enumeration seem essential to generating a predictive algorithm.     

Peripheral blood stem cell collection and transplantation using the Haemonetics Multi Component System

AIM: To assess clinical usefulness of an intermittent-flow blood cell separator in peripheral blood stem cell (PBSC) collection and transplantation. RESULTS: The Haemonetics Multi Component System (Multi) was used to collect PBSC (52 aphereses in 17 patients). The mean processing blood volume and the mean PBSC yield were 7407 ml and 2.16 x 10(6) CD34+ cells/kg, respectively. When CD34+ cells exceeded 0.3% of the peripheral WBC, more than 2.0 x 10(6) CD34+ cells/kg could be collected by a single apheresis. Eight patients underwent PBSC transplantation after high-dose chemotherapy. Hematopoietic recovery was achieved in a median period of 10 days. CONCLUSIONS: (1) A single-arm, light-weight machine has sufficient capability to collect PBSC. (2) The percentage of CD34+ cells in the peripheral WBC is a good predictor of the CD34+ cell yield of the collection.     

Peripheral blood cell telomere length measurements indicate that hematopoietic stem cell turnover is not significantly increased in whole blood and apheresis PLT donors

BACKGROUND: The telomere length (TEL) of peripheral blood leukocytes (PBLs) can be used to estimate hematopoietic stem cell turnover. The current study investigated whether the repetitive stimulation of the hematopoietic system caused by regular whole blood (WB) and PLT donations would affect PBL TEL. STUDY DESIGN AND METHODS: PBLs were obtained from healthy donors (n=94) with a history of at least 3 years of WB donation (median, 7.7 years; range, 3.0-43.0 years) plus additional apheresis PLT donations. The median (range) numbers of WB and PLT donations were 22.0 (6.0-194.0) and 42.0 (7.0-336.0), respectively. Additionally, samples were obtained from healthy nondonors (n=47). PBL TEL was measured with fluorescence in situ hybridization and flow cytometry (flow-FISH). Flow-FISH results were expressed in molecular equivalents of soluble fluorochrome units (MESF; 1000 MESF=1 kMESF) either as absolute (TEL) or as age-adjusted TEL (DeltaTEL). RESULTS: Donor granulocyte and lymphocyte TELs were 12.6 +/- 0.3 (mean +/- SEM) and 13.2 +/- 0.3 kMESF, respectively. No differences were observed when compared with corresponding nondonor data (granulocytes, 12.5 +/- 0.4 kMESF; lymphocytes, 13.6 +/- 0.5 kMESF). Furthermore, DeltaTEL values did not differ between the two groups and were not different from previously established reference values. In addition, neither donor data for age-adjusted TEL for granulocytes nor DeltaTEL for lymphocytes were correlated with either total years or total numbers of WB and/or PLT donations. CONCLUSION: Long-term WB and PLT donation does not affect PBW TEL as measured by flow-FISH, arguing against a significantly increased stem cell turnover.     

外周血干细胞移植治疗神经系统疾病:可能,可行与可信

背景:外周血干细胞可转分化成各种神经细胞,产生多种神经营养因子,而且已经在一些神经系统疾病的试验治疗中取得了可喜效果,如何优化其培养条件,使其扩增并定向分化成为研究热点.目的:就近年来外周血干细胞在脑损伤、遗传缺陷性或退行性疾病的研究和应用进行综述.方法:应用计算机以peripheral blood stem cell,neural,repair为检索词,检索Pubmed数据库(1999-01/2009-09);应用计算机以外周血干细胞、神经、修复为检索词,检索中国期刊网全文数据库(1999-01/2009-09). 结果与结论:共收集221篇关于外周血干细胞方面的文献,中文41篇,英文180篇,排除发表时间较早、重复及类似研究,纳入27篇符合标准的文献.外周血干细胞能在体外扩增,转分化成各种神经细胞,可以到达中枢神经系统的神经受损处,分化成类神经元,并改善受损区域的相关功能.关于外周血干细胞的分化机制目前了解不是很充分,但是大量研究表明外周血干细胞具有的表面标记抗原与其生物学特征密切相关.虽然关于外周血干细胞表面标记物的研究有许多,但是研究人员一直无法确定一个可靠的可以直接标记外周血干细胞的标志.由于CD34功能尚未明确,一直被公认为参与早期造血CD34是造血干细胞的标志物的理论近年受到挑战.如何提高外周血干细胞在体内的成活率,以及提高其向神经元样细胞定向分化等问题还需进一步分析.     

ABO血型不合供者外周血造血干细胞的采集及移植效果研究

目的探讨应用CS-3000 Plus血细胞分离机采集ABO血型不合供者外周血造血干细胞的效率及不去除红细胞和/或血浆进行异基因外周血造血干细胞移植(PBSCT)的安全性。方法经G-CSF 5μg/(kg.d)动员的异基因外周血干细胞供者33名,应用CS-3000 Plus血细胞分离机的干细胞采集程序于动员后d 5采集,其中ABO血型主要不合12名,次要不合8名以及ABO血型相合13名。根据供者外周血的红细胞压积(Hct)和单个核细胞(MNC)计数,对分离机参数作相应调整。输注前从产品袋中留取干细胞,检测有核细胞数、MNC比例、CD34+细胞数、红细胞、血浆含量。单次处理循环血量(9 986±2 489)ml,抗凝剂用量(971±162)ml。供者采集前注射10%葡萄糖酸钙,以预防低钙反应。观察PBSC输注后受者的生命体征、尿液颜色及是否有溶血相关不良反应等。结果ABO血型主要不合组、次要不合组与ABO血型相合组采集物中的有核细胞数、CD34+细胞数、MNC比例无统计学差异(P>0.05),3组供者每次采集的PBSC产品终体积近60 ml,ABO主要不合组采集物中混入红细胞为(3.67—10.25)×1010/袋,ABO次要不合组采集物中血浆量为22—38 ml,不去除红细胞及血浆,直接回输给受者,均未出现溶血反应,所有患者造血功能均获得重建。结论应用CS-3000 Plus血细胞分离机采集ABO血型不合供者的外周血干细胞,通过调整分离机参数,减少ABO血型不合红细胞的混入,可以获得足够的干细胞数量并安全用于移植。     

Background, rationale, and design of a clinical trial to assess the effects of platelet dose on bleeding risk in thrombocytopenic patients

Outlined is the background and rationale for the initiation of a randomized prospective platelet transfusion trial to evaluate the effects of platelet dose on hemostasis and platelet utilization rates. This clinical trial is being performed by the newly established Transfusion Medicine/Hemostasis Clinical Trial Network supported by the National Heart, Lung, and Blood Institute of the National Institutes of Health. The trial will randomize 1,350 patients into three platelet transfusion arms based on body surface area (BSA). The lower dose will be 1.1 x 10(11) platelets/m(2), the medium dose will be 2.2 x 10(11) platelets/m(2), and the higher dose will be 4.4 x 10(11) platelets/m(2). The primary outcome measure will be the incidence of Grade 2 bleeding; i.e., gross hemorrhage without the need for red cell transfusion. Major secondary outcome measures will be the total number of platelets transfused, the total number of platelet transfusion events, the highest grade of bleeding, and bleeding severity. It is expected that this clinical trial will change platelet transfusion practice by identifying whether low-dose platelet transfusion therapy provides adequate hemostasis and what is the most cost-effective strategy for providing platelet transfusions.     

Impact of apheresis automation on procedure quality and predictability of CD34+ cell yield

Success of peripheral blood stem cell (PBSC) collections depends on patient biological parameters and stable apheresis device performance. We investigated product quality and factors influencing main apheresis procedure outcomes including CD34⁺ collection efficiency (CE), product volume or platelet CE. We also assessed different CD34⁺ cell yield prediction algorithms. Autologous PBSC collections by Spectra Optia from myeloma and lymphoma patients were analyzed. Complete blood count (CBC) from patient preprocedure and from collected products were assessed. (1) Product yield was calculated, (2) Product CBC was correlated with patient preprocedure variables, and (3) Predictions of CD34⁺ yields based on (a) product CD34⁺ cell concentration in samples after two or four chamber flushes or (b) traditional CE2 benchmark, were compared. 62 procedures in 41 patients were analyzed. 84% of all procedures were run without operator intervention. Median CD34⁺ CE2 was 56.9% (48.8%‐65.2%) and quite stable irrespective of patient conditions, with minor influence from patient white blood cell (WBC) precounts (r_s = –.47; P < .001). Platelet loss correlated with WBC precount (r_s = .46; P < .001), product volume (r_s = .71; P < .0001) and number of chambers collected (r_s = .72; P < .0001). CD34⁺ cell yield was better predicted based on (a) product CD34⁺ cell concentration from samples after 2 and 4 chamber flushes, respectively (r_s = .969; P < .0001 and r_s = .9648; P < .0001) than based on (b) CE2 formula (r_s = .8262, P < .0001). Spectra Optia provides good quality PBSC products with stable and predictable yield regardless of starting conditions. CD34⁺ sampling of product after few chamber flushes could be used to predict CD34⁺ yield.