G-CSF-induced mobilization of peripheral blood stem cells from healthy adults for allogeneic transplantation

Effect of Periodic Granulocyte Colony-Stimulating Factor Administration on Endothelial Progenitor Cells and Different Monocyte Subsets in Pediatric Patients with Muscular Dystrophies

Muscular dystrophies (MD) are heterogeneous group of diseases characterized by progressive muscle dysfunction. There is a large body of evidence indicating that angiogenesis is impaired in muscles of MD patients. Therefore, induction of dystrophic muscle revascularization should become a novel approach aimed at diminishing the extent of myocyte damage. Recently, we and others demonstrated that administration of granulocyte colony-stimulating factor (G-CSF) resulted in clinical improvement of patients with neuromuscular disorders. To date, however, the exact mechanisms underlying these beneficial effects of G-CSF have not been fully understood. Here we used flow cytometry to quantitate numbers of CD34+ cells, endothelial progenitor cells, and different monocyte subsets in peripheral blood of pediatric MD patients treated with repetitive courses of G-CSF administration. We showed that repetitive cycles of G-CSF administration induced efficient mobilization of above-mentioned cells including cells with proangiogenic potential. These findings contribute to better understanding the beneficial clinical effects of G-CSF in pediatric MD patients.

Endothelial Progenitor Cells and Their Potential Clinical Applications in Peripheral Arterial Disease

Endothelial progenitor cells (EPCs) were originally thought to be present only during embryonic development. New evidence suggests that they can persist into adult life, circulate in the peripheral blood and may play an important part in endothelial repair and replacement of dysfunctional endothelium. They may also play a role in the formation of new blood vessels (angiogenesis, vasculogenesis, and arteriogenesis) in ischemic tissues. In addition, EPCs have the potential to endothelialize small-diameter prosthetic vascular bypass grafts and generate a nonthrombogenic surface, thereby increasing the patency rate of these grafts. EPCs may also be used in the clinical assessment of risk of vascular disease. In this review, the authors discuss the potential use of EPCs in the management of peripheral arterial disease (PAD).

Collection of mobilized peripheral blood stem cells from a donor with severe iron deficient anemia

We report a 45-year-old woman with iron deficient anemia (IDA) who underwent a collection of allogeneic peripheral blood stem cells (PBSCs) induced by granulocyte-colony stimulating factor (G-CSF) after a rapid improvement of IDA by iron replacement. Her peripheral red blood cells (RBCs) after iron therapy were composed of two different-sized subpopulations; one consisted of microcytes, which were iron deficient RBCs, and another of normocytes, which were produced after iron replacement. On the first day of PBSC collection, the interface setting was maintained aiming at 2% hematocrit as usual; however, PBSCs could not be collected adequately. Sedimentation of iron deficient, lighter RBCs under centrifugation within a blood cell separator could be similar to that of mononuclear cells, and the lighter RBCs could contaminate the mononuclear cell layer, resulting in the collection of the lighter layers of mononuclear cells than desired. On the second day, we succeeded in obtaining enough PBSCs by collecting heavier layers than those collected on the first day by using a 4% hematocrit and monitoring white blood cell counts of the collection line serially. It should be noted that the lighter RBCs from a donor with a history of IDA could complicate collection of PBSCs.

Transient respiratory disturbance by granulocyte?colony-stimulating factor administration in healthy donors of allogeneic peripheral blood progenitor cell transplantation

BACKGROUND

Allogeneic peripheral blood progenitor cell (PBPC) transplantation requires granulocyte-colony-stimulating factor (G-CSF) administration to mobilize PBPCs in healthy donors. The effects of G-CSF on pulmonary functions, however, have not been clearly elucidated in PBPC donors.

STUDY DESIGN AND METHODS

Respiratory status by measurements of arterial blood gas was prospectively evaluated serially in 25 healthy donors (9 men, 16 women; age, 18-61 years) administered a dose of 10 microg per kg for 5 days.

RESULTS

White blood cell (WBC) counts increased in all the subjects after G-CSF administration; means on Days 0, 3, and 5 were 6 x 10(9), 33.4 x 10(9), and 33.6 x 10(9) per L, respectively. The mean PaO(2) values on the respective days were 93.1, 85.8, and 81.8 mmHg, and these changes were significant (p < 0.0001), remaining significant after adjustment for the WBC count. Levels of both PaCO(2) and AaDO(2) were significantly higher after G-CSF administration than those before G-CSF administration (p < 0.0001 and p = 0.0004, respectively). SaO(2) was significantly decreased after G-CSF administration (p = 0.0002). Age was identified as a significant predictive factor for the increase of AaDO(2) and PaO(2) decline. These observations clearly indicate that the gas exchange was significantly affected during G-CSF administration in healthy PBPC donors.

CONCLUSION

Considering an increasing use of PBPC mobilization by G-CSF, careful monitoring of the respiratory status is important to ensure safety of PBPC donors, especially elderly donors.

Granulocyte Colony-Stimulating Factor A Noninvasive Regeneration Therapy for Treating Atherosclerotic Peripheral Artery Disease

BACKGROUND

The purpose of this study was to determine whether treatment with granulocyte colony-stimulating factor (G-CSF), which mobilizes endothelial progenitor cells from bone marrow, can safely improve the clinical outcomes of patients with atherosclerotic peripheral artery disease (PAD).

METHODS AND RESULTS

Thirty-nine patients with intractable PAD were randomly assigned to 3 groups: a negative control group (n=12) treated with conventional drug therapy; a positive control group (n=13) treated with conventional drug therapy plus bone marrow transplantation (BMT); and a G-CSF group (n=14) treated with conventional therapy plus subcutaneous injection of 2-5 microg/kg of recombinant human G-CSF once daily for 10 days. One month after treatment, subjective symptoms improved significantly in the G-CSF and BMT groups. Ankle-brachial pressure index and transcutaneous oxygen pressure increased significantly in the BMT and G-CSF groups, but no such improvements were seen in the group receiving conventional therapy alone.

CONCLUSIONS

G-CSF improves the clinical signs and symptoms of patients with intractable PAD to the same degree as BMT does. This noninvasive treatment may thus represent a useful new approach to managing the disease.

Allogeneic peripheral blood stem cell transplantation from two- or three-loci-mismatched related donors in adult Japanese patients with high-risk hematologic malignancies

With the increasing frequency of haploidentical transplantation, it is becoming more important to establish the degree of HLA mismatch that can be accepted. We retrospectively analyzed clinical data of 50 adult Japanese patients with high-risk hematologic malignancies who underwent allogeneic peripheral blood stem cell transplantation (PBSCT) from two- or three-loci-mismatched related donors with HLA class I and II gene disparities in the graft-versus-host direction. They were treated at 20 transplant centers between 1996 and 2002. In all, 18 patients received unmanipulated PBSC, while 32 received purified CD34+ blood cells. Conventional (n=31) or reduced-intensity (n=19) conditioning regimens were used. Of the 39 patients (78%) who survived for > or =28 days after transplant, 37 (95%) achieved neutrophil engraftment, while graft failure and rejection occurred in two of 39 (5%) and three of 37 (8%) patients, respectively. Stepwise Cox regression analysis revealed a significantly lower incidence of grades II-IV acute GVHD in patients receiving purified CD34+ cells (hazard ratio 0.32; 95% CI 0.12-0.84; P=0.022). By 1 year post transplant, 28 patients (56%) had died of transplant-related problems, including infectious complications (30%). Although the number of patients is small, our data suggest that transplant-related problems, particularly infectious complications, are major obstacles to the success of this therapy.

Influence of transplanted dose of CD56+ cells on development of graft-versus-host disease in patients receiving G-CSF-mobilized peripheral blood progenitor cells from HLA-identical sibling donors

We investigated effects of variations in the cellular composition of G-CSF-mobilized peripheral blood progenitor cell (G-PBPC) allografts on clinical outcomes of allogeneic PBPC transplantation. We retrospectively analyzed transplanted doses of various immunocompetent cells from 27 HLA-identical sibling donors in relation to engraftment, incidence of graft-versus-host disease (GVHD), and survival. Significant variability was documented in both absolute numbers and relative proportions of CD34+, CD2+, CD3+, CD4(high)+, CD4+25+, CD8(high)+, CD19+, CD56+, and CD56+16+ cells contained in these allografts. Stepwise Cox regression analysis revealed that the CD56+ cell dose was significantly inversely correlated with the incidence of GVHD. Thus, there was a significantly higher incidence of grade II acute GVHD in patients receiving a lower CD56+16+ cell dose (hazard ratio (HR) 0.0090; 95% confidence interval (CI), <0.00001-3.38; P=0.031), a higher incidence of chronic GVHD in those receiving allografts with a lower CD56+16+ to CD34+ ratio (HR <0.00001; 95% CI <0.00001-0.0007; P=0.0035), and a higher incidence of extensive chronic GVHD in those receiving allografts with a lower CD56+ to CD34+ ratio (HR <0.00001; 95% CI <0.00001-0.053; P=0.0083). These results suggest that CD56+ cells in G-PBPC allografts from HLA-identical sibling donors may play an important role in preventing the development of GVHD.

New approaches to hematopoietic cell transplantation in oncology

The use of high-dose chemotherapy followed by autologous HCT and the use of allogeneic HCT in children and adolescents with high-risk ALL, AML, and NBL has successfully improved outcomes. For other diseases, however, the role of HCT in treatment remains a subject of further research. The availability of HCT was significantly expanded by developing alternative graft sources that currently include BM, peripheral blood, and UCB from autologous and allogeneic related or unrelated donors. Progress in autologous HCT has been achieved by the identification of more effective and less toxic preparative regimens and by ex vivo purging of stem cell products. In allogeneic HCT, graft-versus-leukemia or graft-versus-tumor effects are being exploited increasingly to lower relapse rates. In addition, immunomodulation to promote tolerance, as well as allogeneic antitumor reactions have been achieved by antibody therapy, cytokine therapy, or cell-based immunotherapy. Future improvements are likely, as evidenced by promising preliminary results in the development of stem cell collection techniques, in vitro stem cell expansion, and purging techniques of stem cell grafts. The development of less intensive or nonmyeloablative preparative regimens may further reduce regimen-related morbidity and mortality Specific immunotherapy may facilitate tolerance induction in mismatched allogeneic HCT and support allogeneic HCT in the setting of donor-host HLA disparity. Ultimately, advances in cytokine therapy, tumor-specific vaccines, and gene therapy may decrease or even eradicate recurrence of the malignant disease after HCT.

Successful treatment of progressive NK cell lymphoma with allogeneic peripheral stem cell transplantation followed by early cyclosporine tapering and donor leukocyte infusions

We describe a patient with progressive natural killer (NK) cell lymphoma who was treated successfully with allogeneic peripheral blood stem cell transplantation (allo-PBSCT) followed by early cyclosporine (CsA) tapering and donor leukocyte infusion (DLI). Because the disease showed early resistance to conventional chemoradiotherapy, we performed high-dose chemotherapy followed by allo-PBSCT. After achieving hematologic engraftment, the patient underwent early tapering of CsA and DLI in an attempt to induce a graft-versus-lymphoma effect. Although the disease was in a progressive state at the time of transplantation, complete remission was obtained after allo-PBSCT. As of this report, the patient has been well for more than 2 years.

Mobilization of allogeneic peripheral blood progenitor cells

It is possible to reliably obtain sufficient PBSC from most normal donors to perform allogeneic transplantation. The mobilization regimen, usually administration of a single daily dose of G-CSF at 7.5 to 10 micrograms/kg subcutaneously for 4 to 6 days, is tolerable with acceptable side effects. However, there is wide variability among individuals with respect to the extent of mobilization achieved by the regimen and the optimal timing of apheresis. Studies suggest that the likelihood of obtaining an adequate harvest of CD34+ cells, as defined locally may be enhanced by employing higher doses or different schedules of G-CSF, monitoring the mobilization and/or collection of PBPC, and using apheresis procedures processing 2 or more times blood volume. However, an optimal regimen for mobilization and harvesting for all donors has not yet been identified and a small percentage of donors may not mobilize adequately with G-CSF. Alternative regimens employing combinations of G-CSF and GM-CSF are available that may prove useful in such cases and novel cytokines that are even more effective than G-CSF in mobilizing stem cells are eagerly awaited. Based on currently available experience with normal donors, the short-term safety of G-CSF appears to be acceptable, however there exist several scenarios in which marrow harvesting may be preferable to G-CSF mobilization and apheresis collection of PBPC.

Hepatic graft-versus-host disease presenting as an acute hepatitis after allogeneic peripheral blood stem cell transplantation

Hepatic graft-versus-host disease (GVHD) generally presents as cholestatic jaundice, and increased serum alkaline phosphatase (ALP) is followed by hyperbilirubinemia and clinical jaundice. Currently accepted standards for evaluating the clinical severity of GVHD are based not on serum aminotransferase levels but on the serum bilirubin level. We describe a 17-year-old Japanese female who had increased aminotransferases without cholestasis on day 23 after allogeneic peripheral blood stem cell transplantation (allo-PBSCT). Liver biopsy revealed lymphocytic infiltration of the portal tracts and pericentral necrosis of the lobuli. The limiting plates were not clearly defined due to cellular infiltrates. There was periductal lymphocytic infiltration and vacuolization of the biliary epithelial cells with exocytosis, compatible with GVHD of cholangiohepatitic type. These findings indicate that acute hepatic GVHD may present as acute hepatitis and this should be included in the differential diagnosis for patients with increased aminotransferases after allogeneic stem cell transplantation.

Pharmacokinetics and adverse events following 5-day repeated administration of lenograstim, a recombinant human granulocyte colony-stimulating factor, in healthy subjects

Recombinant human granulocyte colony-stimulating factor (rhG-CSF) (lenograstim) was administered to healthy subjects at doses of 2, 5 and 10 micrograms/kg/day for 5 days (twice a day subcutaneously) to examine the optimal dose and schedule of lenograstim in mobilizing peripheral blood progenitor cells (PBSC) for allogeneic transplantation. Lenograstim administration significantly increased CD34+ cells in a dose-related manner. A significant correlation was observed between the maximal post-dosing counts and the pre-dosing baseline counts of CD34+ cells. Peripheral neutrophils increased markedly by seven to 13 times from the baseline to a peak of approximately 40,000/microliter on day 5 for the 5 and 10 micrograms/kg/day doses. After peak serum concentration (Cmax) was attained 4 h following administration, serum G-CSF declined with time in a log-linear fashion. The Cmax and 12 h area-under-the-curve increased dose dependently, but minimum drug level increased up to day 2 and then decreased until day 5. Clearance decreased with increasing dosage at the first dose, and increased significantly at the last dose. We found a highly significant correlation between absolute neutrophil counts and clearance for each dose. Adverse events most frequently occurred on day 6, with increases of alkaline phosphatase and lactate dehydrogenase and onset of bone pain. Increases of aspartate aminotransferase and alanine aminotransferase occurred as delayed events. Platelet count gradually decreased after the end of drug administration to 57% of the pre-dosing count on day 10, but was still within the normal range. These preliminary results suggest that repeated doses of lenograstim induce mobilization of PBSC in a dose-dependent manner and the pre-dosing baseline count of PBSC may predict the post-dosing maximal mobilization. The drug treatment may cause delayed-onset moderate thrombocytopenia and increased transaminase, and the drug clearance changes in a complex manner during repeated dosing.

Allogeneic peripheral blood stem cell transplantation for the treatment of chronic active Epstein-Barr virus infection

The prognosis of chronic active Epstein-Barr virus infection (CAEBV) is very poor. We describe a 24-year-old male with severe CAEBV who was treated with allogeneic peripheral blood stem cell transplantation (allo-PBSCT). On admission, EBER-1 in lymphocytes infiltrating the liver, EBV-DNA in peripheral blood mononuclear cells (PBMC) and monoclonal NK cell proliferation were confirmed. After unsuccessful chemotherapy, he received an allo-PBSCT from his HLA-identical sister. Although he died of pulmonary hemorrhage on day +19, EBV-DNA was undetectable by PCR in PBMC, and the post-mortem liver showed no EBER-1-positive lymphocytes. This experience suggests that EBV-positive lymphocytes in CAEBV may be eradicated by allo-PBSCT, thereby raising the possibility of a new treatment modality. Bone Marrow Transplantation (2000) 26, 805-808.

Unusual adverse events following peripheral blood stem cell (PBSC) mobilisation using granulocyte colony stimulating factor (G-CSF) in healthy donors

Here, we describe two cases of severe pyogenic infection in healthy donors diagnosed immediately following stem cell mobilisation with G-CSF. In the first donor a painful perianal abscess and in the second one an apical abscess required surgical incision. The reported serious adverse events in the literature are reviewed and the potential pathophysiological role of G-CSF or GM-CSF in augmenting inflammatory processes is discussed. In the light of a rapidly increasing number of related and unrelated peripheral blood stem cell donations the need for more comprehensive donor work-up and follow-up for peripheral blood stem cell donors has to be considered. Bone Marrow Transplantation (2000) 26, 811-813.

Granulocyte colony-stimulating factor versus granulocyte-macrophage colony-stimulating factor for collection of peripheral blood progenitor cells from healthy donors

The harvesting of peripheral blood progenitor cells (PBPCs) after granulocyte colony-stimulating factor or granulocyte-macrophage colony-stimulating factor stimulation instead of bone marrow in healthy donors has become increasingly popular. Donors, given the choice between bone marrow and PBPC donation, often prefer cytapheresis because of the easier access, no necessity for general anesthesia, and no multiple bone marrow punctures. In addition, accelerated engraftment and immunomodulation by granulocyte colony-stimulating factor-mobilized PBPCs are advantageous for the recipient. However, because of donor inconvenience and poor mobilization, there is a need to develop improved procedures. Aspects such as durability of hematopoietic engraftment, characterization of the earliest stem cell, and composition of PBPCs are not yet well defined, and international donor registration and follow-up must be considered when evaluating long-term safety profiles in healthy donors. This review concentrates on the most significant developments on mobilization of PBPCs published during the past year.

Production of Soluble Granulocyte Colony-Stimulating Factor Receptors from Myelomonocytic Cells

It has been speculated that a soluble form of G-CSFR might be physiologically present in humans, since G-CSFR mRNA that lacks a transmembrane domain has been identified from a human myelomonocytic cell line. Here, we demonstrate human soluble G-CSFR (sG-CSFR) of two different molecular sizes (80 and 85 kDa) on an immunoblot analysis using Abs generated against the amino-terminal, extracellular domain of the full-length G-CSFR. Both isoforms of sG-CSFR were able to bind recombinant human G-CSF (rhG-CSF). RT-PCR analysis with primers targeted outside of the transmenbrane region revealed that membrane-anchored G-CSFR is expressed at all maturation stages of purified myeloid cells, including CD34+CD13+ cells (blasts), CD11b−CD15+ cells (promyelocytes or myelocytes), CD11b+CD15+ cells (metamyelocytes and mature neutrophils), and CD14+ cells (monocytes). On the other hand, sG-CSFR mRNA was detectable in CD11b−CD15+, CD11b+CD15+, and CD14+ cells, but not in the CD34+CD13+ blast population. The serum concentration of both isoforms of sG-CSFR appeared to be correlated with the numbers of neutrophils/monocytes before and after rhG-CSF treatment in normal individuals. Thus, two isoforms of sG-CSFR are physiologically secreted from relatively mature myeloid cells and might play an important role in myelopoiesis through their binding to serum G-CSF.

High-versus standard-dose filgrastim (rhG-CSF) for mobilization of peripheral-blood progenitor cells from allogeneic donors and CD34(+) immunoselection

PURPOSE

The efficacy of a high- versus a standard-dose filgrastim (recombinant human granulocyte colony-stimulating factor, or rhG-CSF) regimen to mobilize peripheral-blood progenitor cells (PBPCs) for allogeneic transplantation was investigated in 75 healthy donors.

PATIENTS AND METHODS

From December 1994 to December 1997, 75 consecutive donors (median age, 38 years; range, 17 to 67 years) were assigned to two different schedules of rhG-CSF for PBPC mobilization. Fifty donors received 24 microg rhG-CSF/kg body weight (BW) divided into two daily subcutaneous injections (two doses of 12 microg, group A), whereas 25 were treated with 10 microg rhG-CSF once daily (group B). Apheresis was started on day 4 in group A and on day 5 in group B. Target CD34(+) cell numbers in apheresis products were >/= 4 x 10(6)/kg recipient BW.

RESULTS

Cytokine priming and collection of PBPCs were equally well tolerated in both groups. Significantly higher CD34(+) cell numbers in group A with 3. 7 x 10(6)/kg recipient BW/apheresis (0.47 x 10(6)/L apheresis) compared with 2 x 10(6)/kg recipient BW/apheresis (0.25 x 10(6)/L apharesis) in group B were obtained (P <.05). Using standard aphereses (median, 9 L), two doses of 12 microg rhG-CSF/kg allowed collection of >/= 4 x 10(6)/kg CD34(+) cells with two aphereses (range, one to three) in group A versus three aphereses (range, one to six) in group B (P <.015). Donor age, sex, and BW influenced the collection of CD34(+) cell numbers: in particular, significantly higher apheresis results were obtained in donors younger than 40 years compared with donors older than 40 years of age (P <.05). In 65 CD34(+) selection procedures using avidin-biotin immunoabsorption columns (Ceprate SC System, CellPro, Bothell, WA), a median CD34(+) purity of 53%, CD34(+) recovery of 40%, and the collection of 2 x 10(6)/kg CD34(+) cells/selection were achieved. In group A with higher CD34(+) cells/kg/apheresis, CD34(+) purity, recovery, and cell yields were 60%, 45%, and 2.3 x 10(6)/kg/selection, respectively, as compared with 48%, 31%, and 0.7 x 10(6)/kg in group B (P <.05).

CONCLUSION

Our results demonstrate that twice daily rhG-CSF (two doses of 12 microg/kg BM) compared with once daily rhG-CSF (10 microg/kg BW), in addition to being well tolerated, significantly improves PBPC mobilization, allows the collection of higher numbers of CD34(+) cells with one or two standard aphereses, and facilitates subsequent selection procedures in healthy allogeneic donors.

Mobilization of blood-derived stem and progenitor cells in normal subjects by granulocyte-macrophage- and granulocyte-colony-stimulating factors

BACKGROUND

It was previously reported that the combination of granulocyte-macrophage-colony-stimulating factor (GM-CSF) and granulocyte-CSF (G-CSF) for 4 days mobilized more primitive CD34+ subsets than did either G-CSF or GM-CSF alone.

STUDY DESIGN AND METHODS

The studies determine the optimal number of days of growth factor dosing for mobilization and collection of peripheral blood progenitor cells, by increasing the days of administration of GM-CSF and/or G-CSF or employing the sequential administration of GM-CSF followed by G-CSF. Sixty normal subjects were given injections of G-CSF or GM-CSF alone; GM-CSF and G-CSF concurrently for 4, 5, or 6 days; or a sequential regimen of GM-CSF for 3 or 4 days followed by G-CSF for 2 or 3 days. A 10-L apheresis was performed 24 hours after the last dose.

RESULTS

The three most efficacious mobilization regimens consisted of sequential GM-CSF for 3 days followed by G-CSF for either 2 or 3 days and G-CSF alone for 5 days. Each of these regimens resulted in the collection of significantly greater numbers of CD34+ cells by apheresis than any of the 4-day dosing regimens with G-CSF and/or GM-CSF (sequential GM-CSF/G-CSF: 3 days/2 days = 3.58 +/- 0.53 x 106 CD34+ cells/kg; GM-CSF/G-CSF: 3 days/3 days = 4.45 +/- 1.08 x 10(6) CD34+ cells/kg; G-CSF: 5 days = 3.58 +/- 0.97 x 10(6) CD34+ cells/kg; all p<0.05 vs. G-CSF and/or GM-CSF for 4 days). Clonogenic assays generally paralleled the level of CD34+ cells. Regimens containing GM-CSF resulted in a higher percentage of the cells from primitive CD34+/CD38-/HLA-DR+ subset than G-CSF alone.

CONCLUSION

Compared with 4-day dosing regimens with G-CSF and/or GM-CSF, mobilization of CD34+ cells in normal subjects using sequential GM-CSF for 3 days followed by G-CSF for 2 or 3 days or using G-CSF alone for 5 days increased the number CD34+ cells that can be collected by a single 10-L apheresis 24 hours after the last dose of cytokine.

Factors influencing yields of progenitor cells for allogeneic transplantation: optimization of G-CSF dose, day of collection, and duration of leukapheresis

Mobilization of hematopoietic progenitor cells by G-CSF was attempted on 89 occasions in 85 healthy donors. Three dose ranges of G-CSF were chosen for analysis: low (4-7.4 micrograms/kg), intermediate (7.5-10 micrograms/kg) and high (> 10 micrograms/kg). A target blood level for apheresis of 20 x 10(6)/L CD34+ cells was reached by day 3 in 75 patients (84%) and by day 4 in all but 1 (99%). Target yields above 2.5 x 10(6)/kg for 75 unmanipulated transplants were exceeded in a single collection in 73 donors (97%). Correlation of CD34+ cell yields to blood CD34+ cell level before leukapheresis was moderate only (r2 = 0.32). There was close linear correlation between processed volume and cumulative CD34+ cell yield, with a median r2 value of 0.98 (range 0.74-1.00). Yields of CD34+ cells achieved on day 3 were significantly lower after the high dose than after the intermediate G-CSF dose (21 +/- 3 versus 29 +/- 6 x 10(6)/L blood processed, p = 0.03). After the low dose of G-CSF, yields on day 4 were higher than on day 3 (48 +/- 10 versus 22 +/- 4 x 10(6)/L blood processed, p = 0.01). There was no difference between day 3 and day 4 yields with the intermediate G-CSF dose. In 73 of 93 (78%) leukaphereses, the CD34+ cell yield was more than 100% of the estimated intravascular CD34+ cells at the beginning of collection and ranged up to 342%. These data indicate that a daily dose of 7.5-10 micrograms/kg G-CSF, given as a multiple of 300 and 480 micrograms ampoules, is a convenient regimen giving adequate yields from a single collection on day 3 or 4 in most donors. Measuring blood CD34+ cell levels is of limited value in predicting yields, but monitoring CD34+ cell yields during leukapheresis may help to minimize unnecessary or inefficient collection.

Allogeneic peripheral blood progenitor cells: current status and future directions

Increasing use is being made of mobilized peripheral blood as a source of hematopoietic stem and progenitor cells for transplantation. Initially, these efforts were focused on autologous applications. However, many centers are now using cells derived from normal donors mobilized with recombinant hematopoietic growth factors for allogeneic transplantation. This article reviews the key issues associated with the use of these cells for hematologic reconstitution and summarizes important recent developments in the field.