G-CSF alone mobilizes sufficient peripheral blood CD34+ cells for positive selection in newly diagnosed patients with myeloma and lymphoma

We have evaluated CD34⁺ cell positive selection from granulocyte-colony stimulating factor (G-CSF)-mobilized peripheral blood progenitor cells (PBPC) in 26 patients with either multiple myeloma (MM, n  = 18) or follicular non-Hodgkin's lymphoma (NHL, n  = 8). 26 PBPC were collected with two leukaphereses: 16 contained sufficient numbers of CD34⁺ cells and were selected. The absolute number of CD34⁺ cells in the leukapheresis products was found to be significantly related to the duration of underlying disease and exposure to prior treatment. CD34⁺ cell positive selection allowed recovery of a median of 35% of CD34⁺ cells, the selected fraction containing a median number of 1.43 × 10⁶/kg CD34⁺ cells/kg (range 0.48–41.5). 10 patients were transplanted and received a median dose of 1.51 × 10⁶ CD34⁺ cells (range 0.48–4.2). The median time to granulocyte (>0.5 × 10⁹/l) and platelet (>20 × 10⁹/l) engraftment was 12 and 13 d respectively (ranges 10–13 and 0–95). Lymphoma cells were found by a sensitive polymerase chain reaction technique in four out of five CD34⁺ cell fractions tested.     

Transplantation of HLA-mismatched CD34+ selected cells in patients with advanced malignancies: severe immunodeficiency and related complications

This trial was designed to test the use of CD34⁺ selected haemopoietic stem cells (HSC) in HLA-mismatched donor–recipient pairs, following intensive conditioning with thiotepa, antilymphocyte globulin (ALG), cyclophosphamide and single-dose total-body irradiation (sTBI). 10 patients aged 16–50 with advanced malignancies and a two- or three-antigen mismatched family donor entered this study. Donor marrow and G-CSF primed peripheral blood cells were processed separately on CD34 columns (Ceprate). The median number of infused CD34⁺ cells were 5.66 × 10⁶/kg, with 0.55 × 10⁶/kg CD3⁺ cells. Nine patients received cyclosporin for graft-versus-host disease (GvHD) prophylaxis. Median neutrophil counts on day 21 were 2 × 10⁹/l with a median platelet count of 60 × 10⁹/l, but CD4 counts remained extremely depressed throughout the study. Acute GvHD was scored as grade 0–I in two patients, as grade II in seven, and grade III in one. Eight patients died at a median interval of 72 d from HSCT (range 20–144) due to cytomegalovirus (CMV) associated interstitial pneumonitis (IP) ( n  = 5), renal failure ( n  = 1), GvHD ( n  = 1) and Aspergillus meningitis ( n  = 1). Two patients are alive 365–495 d post transplant, one in remission and one in relapse.
This study suggests that large numbers of positively selected mismatched HSC can rapidly engraft after intensive conditioning regimen: however, profound post-transplant immunodeficiency leads to a high risk of lethal infectious complications.     

Immunomagnetic selection of CD34+peripheral blood stem cells for autografting in patients with breast cancer

Contamination of transplants with tumour cells may contribute to relapse after peripheral blood stem cell transplantation (PBSCT). We studied the feasibility of CD34⁺ cell selection from blood-derived autografts obtained following G-CSF-supported cytotoxic chemotherapy in a group of 25 patients with breast cancer (10 with high-risk stage II/III and 15 with stage IV without bone or bone marrow involvement).
Using immunomagnetic beads (Isolex 300 SA, Baxter) CD34⁺ cells were enriched and released by chymopapain resulting in a median purity of 95% (range 82–99%) and a median recovery of 80% (range 27–132%). The enrichment procedure did not change the proportion of CD34⁺ subsets coexpressing HLA-DR, CD38 and Thy-1, while L-selectin was removed from the cell surface following selection. Using a sensitive immunocytological technique with a cocktail of epithelial-specific antibodies (anti-cytokeratin 8, 18 and 19; HEA125; BM7 and BM8), five leukaphereses products contained epithelial cells, whereas the selected CD34⁺ cell fraction was free of tumour cells. A neutrophil count of 0.5×10⁹/l and a platelet count of 20×10⁹/l was reached after a median time of 14 and 10 d following 40 high-dose chemotherapy (HDC) cycles. Our results indicate that immunomagnetic selection of CD34⁺ cells yields highly purified autografts devoid of tumour cells whereas the engraftment ability of the progenitor and stem cells is fully retained.     

Progenitor cell subsets and engraftment kinetics in children undergoing autologous peripheral blood stem cell transplantation

The main objective of the present study was to determine the role of CD34⁺ cell subsets in the haemopoietic recovery of children undergoing peripheral blood stem cell transplantation. For this purpose, 38 leukaphereses from 33 children with malignancies mobilized with G-CSF were analysed. Using dual-colour flow cytometry, different subpopulations of CD34⁺ cells were quantified and the number of each reinfused subsets correlated with haemopoietic resurgence. Multivariate analysis showed that the number of CD34⁺CD38⁻ cells and CD34⁺CD38⁺ cells correlated better with time to neutrophil and platelet recovery, respectively, than the total number of CD34⁺ cells. Threshold values for rapid haemopoietic recovery, determined by the receiver operating characteristic analysis, were found to be 0.5 × 10⁶ CD34⁺CD38⁻ cells for neutrophil engraftment, and 2.0 × 10⁶ CD34⁺CD38⁺ cells for platelet recovery. It is suggested that the analysis of CD34⁺ cell subsets could increase understanding of the repopulation capacity of a given leukapheresis product in peripheral blood stem cell transplantation procedures in children. In particular, this procedure could be extremely useful when low numbers of CD34⁺ cells are collected.     

IVE (ifosfamide, epirubicin and etoposide) is a more effective stem cell mobilisation regimen than ICE (ifosphamide, carboplatin and etoposide) in the context of salvage therapy for lymphoma

Two commonly used chemotherapy regimens for lymphoma salvage therapy were compared: ICE (ifosphamide, carboplatin and etoposide) ± rituximab and IVE (ifosfamide, epirubicin and etoposide) ± rituximab, for their efficacy in mobilising peripheral blood stem cells for autologous transplantation. Significant differences were observed between the cohorts in terms of number of patients mobilising the stipulated minimum >2 × 10⁶ CD34⁺/kg (99·2% in IVE group versus 83% in ICE group: P  =   0·0002) and also in terms of the number of patients achieving the predetermined target of >5 × 10⁶ CD34⁺/kg, both in total and during the first apheresis procedure (72% in IVE versus 51% in ICE group and 49% in IVE versus 7% in ICE group: P  =   0·02 and P  <   0·0001 respectively). This analysis of two similar groups of patients treated within a single-centre appears to demonstrate that the IVE regimen is a more effective stem cell mobilisation regimen than ICE in the context of salvage therapy for Hodgkin and non-Hodgkin lymphoma, allowing more patients to achieve the target CD34⁺ cell collection and proceed to high-dose therapy and autologous stem cell transplantation.     

Combined negative and positive selection of mobilized CD34+ blood cells

We tested four negative and two positive selection methods for separation of CD34⁺ cells from mobilized blood cells, and analysed fold-enrichment, purity and recovery of CD34⁺ cells after selection procedures. The elimination of mature CD34⁻ cells was achieved by adhesion to nylon-wool fibre (5.9 ± 1.0 mean fold-enrichment and 65.2 ± 2.3 mean recovery of CD34⁺ cells). Standard or modified Ficoll-Hypaque and Percoll density gradients, as well as phagocytosis with magnetic beads, were less effective in eliminating CD34⁻ cells, both purity and fold-enrichment of CD34⁺ cells being lower than those obtained with separation by nylon-wool. Both positive selection methods tested, Ceprate and MiniMacs System, generated highly purified CD34⁺ cell populations ranging from 80% to 90%. The recovery of CD34⁺ cells was optimal with MiniMacs (77.9±3.6) and low with Ceprate (28.8±2.8). Based on these results, in two large-scale experiments we combined nylon-wool fibre and MiniMacs System in a two-step separation procedure obtaining a 36.9±2.6 mean fold-enrichment and a 50.5±0.3 mean recovery of CD34⁺ cells. In this way we achieved optimal enrichment and recovery of CD34⁺ cells, with a substantial saving of cost compared to either selection method alone.     

Serum oncostatin M in multiple myeloma: association with prognostic factors

We report on five children with haematological malignancies who underwent allogeneic peripheral blood progenitor cell (PBPC) transplantation. PBPC were harvested from HLA-identical sibling donors after G-CSF (10 μg/kg/d s.c.) mobilization. Aphereses were carried out on day 5 after G-CSF using a Cobe Spectra blood cell separator. All PBPC allografts were cryopreserved before transplantation. The median of CD34⁺ cells and CD3⁺ cells infused were 14.1×10⁶/kg recipient body weight (range 4.92–22.3) and 2.40×10⁸/kg recipient body weight (range 0.54–4.82), respectively. Engraftment occurred in all cases. The median time to a neutrophil count >0.5×10⁹/l and a platelet count >20×10⁹/l were 15 and 14 d, respectively. The incidence of severe acute graft-versus-host disease was 20%. These data suggest that allogeneic PBPC transplantation might be an alternative to bone marrow transplantation in children.     

Collection of peripheral blood stem cells from normal donors 60 years of age or older

We report 14 normal peripheral blood stem cell (PBSC) donors ≥ 60 years of age who had cytokine mobilization followed by PBSC apheresis for allogeneic transplantation. Mobilization was achieved with filgrastim (6 μg/kg twice daily). Their median age was 63.5 years (range 60–77), and 43% had a positive medical history, mainly hypertension and/or cardiac problems. Their median pre-apheresis leucocyte count (×10⁹/l) was 38.6 (range 29.6–63.4). The median apheresis yield (×10⁶ CD34⁺ cells/litre blood processed, first apheresis) was 27.9 (range 1.6–54.8). The target cell dose (≥4& times; 10⁶ CD34⁺ cells/kg recipient) was reached with one procedure in eight (57%) donors. Filgrastim-related adverse events were acceptable and apheresis was well tolerated. When compared to younger donors (<60 years of age), a trend to a lower CD34⁺ apheresis yield and a requirement for more than one apheresis to achieve the collection target (≥4 ×10⁶ CD34⁺ cells/kg) was evident. Although older (≥60 years) donors seem to mobilize less effectively, these data suggest that PBSC collection from them is feasible and has an acceptable short-term safety profile.     

Granulocyte colony-stimulating factor given in addition to interferon-α to mobilize peripheral blood stem cells for autologous transplantation in chronic myeloid leukaemia

In order to potentially mobilize and harvest the Ph⁻ cells observed in most patients with chronic myeloid leukaemia (CML) during interferon-α (IF-α) therapy, G-CSF (filgrastim), 5 μg/kg/d, was administered subcutaneously together with IF-α to 30 CML patients in haematological remission but with various degrees of cytogenetic remission, after IF-α therapy. Peripheral blood stem cells (PBSC ) were harvested using standard aphereses from day 5 of G-CSF. Patients underwent one to four (median three) aphereses. Median total yields/kg were 7.6 (range 3.8–25) × 10⁸ MNC, 3.4 (0–140) × 10⁶ CD34⁺ cells, and 17 (1.1–107) × 10⁴ CFU-GM. No patient had a significant increase in the percentage of Ph⁺ cells in the bone marrow under G-CSF therapy. The percentage of Ph⁺ cells in apheresis products tended to decrease between the first and the last apheresis ( P  = 0.05). 14 patients who were not responsive to IF-α were transplanted after conditioning with busulphan 16 mg/kg and melphalan 140 mg/m². Median time to neutrophils > 0.5 × 10⁹/l was 20 d (16–114 d) and to platelets > 50 × 10⁹/l 18 d (12–149 d). Nine patients had a major cytogenetic response post graft, which correlated with the amount of Ph⁺ cells reinfused with the graft ( P  = 0.02). We conclude that this procedure is feasible, allowing the harvest of enough PBSC, some of them Ph⁻ in patients who responded to IF-α, to allow autologous transplantation.     

Flow cytometric detection of cytomegalovirus antigen in peripheral blood cells after bone marrow transplantation

We report 13 normal peripheral blood stem cell (PBSC) donors who had a second PBSC collection for allogeneic transplantation performed after the first. The median interval between the first and second collection was 5 months. Mobilization was achieved with filgrastim (12 μg/kg/d). No significant difference was found in the median pre-apheresis leucocyte count (×10⁹/l) between the two donations (40.2 v 38.5; P  = 0.91). The median apheresis yield (×10⁶ CD34⁺ cells/litre blood processed, first apheresis) was also similar (28 v 27.3; P  = 0.91). Filgrastim-related adverse events were comparable. These data suggest that second PBSC collections are feasible, similarly tolerated and provide comparable apheresis yields.     

STEM CELL MOBILIzATION IN NORMAL DONORS FOR ALLOGENEIC TRANSPLANTATION: ANALYSIS OF SAFETY AND FACTORS AFFECTING EFFICACY

The use of peripheral blood stem cells instead of bone marrow as the source of haemopoietic cells for allogeneic transplantation is being increasingly explored. We have analysed data from 17 normal donors who underwent stem cell mobilization for allogeneic transplantation with an identical protocol using G-CSF at a dose of 10 μg/kg/d, with the first leukapheresis (LP) on the day following the fourth dose of G-CSF. Both G-CSF administration and leukapheresis were well tolerated. Donors underwent a median of two leukaphereses (range one to three) and a median of 6.80 × 10⁶ CD34⁺ cells/kg recipient weight (range 2.4–15.6 × 10⁶) were collected. The median number of CD34⁺ cells per kg donor weight was 6.05 × 10⁶, when corrected for a 12 litre leukapheresis, this gave a median total of 3.89 × 10⁶ CD34⁺ cells/kg donor weight. When analysed with respect to factors which might influence the efficacy of mobilization, male donors were associated with a superior yield. The median number of CD34⁺ cells/kg/LP harvested was 4.96 × 10⁶ in males and 2.79 × 10⁶ in females ( P <0.05). The results suggested that, given a recipient of 75 kg, in a male donor a single 12 litre leukapheresis should yield sufficient CD34⁺ cells (4 × 10⁶/kg), whereas a female donor would be likely to need two leukaphereses. Age was not found to affect donor yield. In summary, these data confirm that leukapheresis is a safe procedure in normal donors and suggest that males may be more efficient mobilizers of stem cells than females.     

Interferon increases serum thrombopoietin in patients with chronic hepatitis C

We measured serum thrombopoietin (TPO) in chronic hepatitis C treated with interferon (IFN). The platelet count before the therapy was 161.9 ×10⁹ ± 64.1 × 10⁹/l, which decreased to 116.3 × 10⁹ ±  48.4 × 10⁹/l 1 week after IFN therapy ( P  <0.01). On the other hand, serum TPO increased from 1.96 ± 0.60 fmol/ml to 2.68 ± 0.69 fmol/ml ( P  < 0.02). Contrary to a recent report that serum TPO was not altered in liver cirrhosis, these data indicate that serum TPO was increased in chronic hepatitis C in response to thrombocytopenia by IFN therapy.     

All-trans-retinoic acid up-regulates CD38 but not c-Kit antigens on human marrow CD34+ cells without recruitment into cell cycle

Retinoids, especially all- trans -retinoic acid (ATRA), are well known for their differentiating activity on HL-60 cells. Moreover ATRA induces CD38 antigen overexpression on these cells. In this study we examined the effects of ATRA on purified normal CD34⁺ cells from adult human marrows incubated with ATRA (1 μ M ) or stem cell factor (SCF) after 7 d liquid cultures in serum-deprived medium. Before and after the incubation, CD34⁺ cells were studied by flow cytometry to evaluate the cell-surface expression of CD38 and c-Kit antigens and the cycle status of these cells using high-resolution analysis (DNA content v Ki-67 antigen expression) to clarify the functional meaning of antigenic variations. When compared with control cultures, ATRA-treated cells displayed changes in their immunophenotypic profile. Particularly relevant was the up-regulation of CD38 antigen with a mean (±SEM) fold increase of 2.1 ± 0.1 ( P  = 0.028) for geometric mean fluorescence intensity (GMFI), without modulation of c-Kit expression. SCF only down-regulated expression of c-Kit with a fold decrease of 4.6 ± 0.9 for GMFI ( P  = 0.043). Unlike SCF, ATRA did not induce CD34⁺ cells to entry into cell cycle despite increased levels of surface CD38 antigen. Moreover morphological and functional assays did not argue for an ATRA-induced maturation process. Contrary to steady-state cells, CD34⁺ cells treated with pharmacological doses of ATRA alone displayed CD38 over-expression without change in c-Kit levels and cycle status, suggesting an absence of maturation pressure.     

Separation of G-CSF-mobilized PBSC transplants by counterflow centrifugal elutriation: modest enrichment of CD34+ cells but no loss of primitive haemopoietic progenitors

The suitability of counterflow centrifugal elutriation (CCE) for reduction of the number of non-stem cells in autologous G-CSF-mobilized peripheral blood stem cell (PBSC) transplants was investigated. By cell size-monitored CCE, small cells could be rapidly separated from the haemopoietic progenitor cells present in leukapheresis product (LP) samples. The large cell fraction contained an average 86 ± 25% of the CD34⁺ cells and 76 ± 20% of the granulocyte-macrophage progenitors (CFU-GM) loaded into the separation chamber, and was depleted of 75 ± 18% of the lymphocytes, 89 ± 7% of the erythrocytes and 98 ± 2% of the platelets ( n  = 21). Due to the presence of high numbers of large immature myeloid cells, which co-elutriated with progenitor cells, enrichment of CD34⁺ cells in the large cell fraction was only modest (average 1.8 times). No indication of preferential co-elutriation of primitive stem cells with the small cells was obtained. There was no difference in expression of CD38 or Thy-1 on CD34⁺ cells between the two elutriation fractions. Frequencies of cobblestone-area-forming cells (CAFC) week 6, which are considered to represent cells with long-term repopulating ability, were reduced in the small cell fractions as compared to those in the unseparated samples and the large cell fractions. On average, 100% of CAFC week 6 were recovered in the large cell fractions ( n  = 5). In conclusion erythrocytes, platelets and 40–50% of leucocytes can be depleted from G-CSF-mobilized PBSC samples by CCE with an almost complete recovery of both clonogenic and primitive stem cells.     

Splenic lymphoma with villous lymphocytes: clinical presentation, biology and prognostic factors in a series of 100 patients

The diagnosis of splenic lymphoma with villous lymphocytes (SLVL) was assessed by a panel of cytologists in a series of 100 patients. Clinical and biological characteristics were analysed in relation to prognosis.
SLVL is a chronic B-cell lymphoproliferative disorder characterized by splenomegaly and the presence, in peripheral blood, of lymphocytes with 'villous' projections. The cytological diagnosis can be difficult in patients without an absolute lymphocytosis which was observed in 24% of cases. B-cells expressed CD19⁺, CD20⁺, CD22⁺, CD24⁺ and DBA44⁺, whereas the expression of CD5, CD10 and CD25 was usually negative.
SLVL is a disease of the elderly with a relatively benign clinical course. In the present series the 5-year overall survival was 78%. Deaths in 15 patients were related to disease progression or treatment (nine cases). Patients with a leucocyte count >30 × 10⁹/l or lymphocyte count <4 × 10⁹/l or initially treated with chemotherapy had significantly ( P  < 0.001) lower overall survival than other patients. From these findings, treatment abstention should be considered in patients with favourable prognostic factors; on the other hand, the efficacy of conventional chemotherapy remains to be evaluated in patients with unfavourable prognostic factors.     

COLLECTION AND TRANSPLANTATION OF PERIPHERAL BLOOD PROGENITOR CELLS MOBILIzED BY G-CSF ALONE IN CHILDREN WITH MALIGNANCIES

Results of collection and transplantation of peripheral blood progenitor cells (PBPC) mobilized by G-CSF in 31 children with different malignancies were analysed. A total of 43 aphereses were performed, following administration of granulocyte colony-stimulating factor (G-CSF), using a continuous flow blood cell separator (Cobe Spectra) through a central venous catheter. For patients weighing ≤25 kg the extracorporeal line was primed with red blood cells. The mean blood flow rate was 33.2ml/min (range 12–56ml/min). The mean number of mononuclear cells (MNC), granulocyte-macrophage colony-forming units (CFU-GM) and CD34⁺ cells collected were 7.22×10⁸/kg body weight (b.w.), 15.9×10⁴/kg and 5.44×10⁶/kg respectively.
The morbidity related to PBPC collection was low and the mean apheresis time was 302.7min (range 115–492). The volume of processed blood for apheresis (per kilogram body weight) ranged from 117 to 539.6 (mean 309.13ml/kg). 20 patients required only one apheresis to collect the minimum requirement of 5–7×10⁸/kg of MNC.
All patients subsequently underwent autografting with PBPC after myeloablative therapy. Days to achieve an absolute count of neutrophils (ANC) <0.5×10⁹/l and a platelet count of 20×10⁹2/l without platelet support were 9.5 and 18, respectively. The number of CD34⁺ cells infused correlated highly with engraftment kinetics. The extramedullary toxicity was low and manageable.     

Cytokine and chemokine production by CD34+ haemopoietic progenitor cells: detection in single cells

In vitro expansion of haemopoietic progenitor cells (HPC), lineage-specific differentiation, and gene transfer are all based on in vitro culture systems using haemopoietic growth factors (HGF). A close control of the actual culture conditions, however, is difficult due to secondary mediators secreted by the heterogenous population of mature and immature cells in culture. Although monocytes and granulocytes have already been identified as active producers, this study specifically addressed the role of CD34⁺ progenitor cells in this respect. Using an immunostaining method that enables simultaneous detection of cytokines and phenotype, 56±6% CD34⁺ peripheral blood progenitor cells (PBPC) were found to contain cytoplasmic IL-8 after stimulation with phorbol myristate acetate+ionomycin for 90 min, 19±4% stained positive after TNF-α induction (20 h), and 7±1% expressed IL-8 in the presence of culture medium alone. Intra-cytoplasmic TNF-α and IL-1β were detected at lower frequency, and <1% of CD34⁺ cells expressed IL-1ra or IL-6, whereas IL-1α, IL-10 and G-CSF were not detected. Thus, CD34⁺ HPC are able to synthesize chemo- and cytokines that may operate in an auto- or paracrine manner to modulate in vivo as well as in vitro growth and differentation of haemopoietic cells.     

Oxidative DNA damage in CD34+ myelodysplastic cells is associated with intracellular redox changes and elevated plasma tumour necrosis factor-α concentration

Ineffective haemopoiesis in the myelodysplastic syndromes (MDS) is mediated, at least in part, by apoptosis, though the mechanisms of apoptotic induction are unclear. Tumour necrosis factor-α (TNF-α) promotes apoptosis via intracellular oxygen free radical production, oxidation of DNA and proteins, and is increasingly implicated in the pathogenesis of MDS. Using single-cell gel electrophoresis, we have identified oxidized pyrimidine nucleotides in the progenitor-enriched bone marrow CD34⁺ compartment from MDS patients ( P  = 0.039), which are absent in both CD34⁻ MDS cells ( P  = 0.53) and also CD34⁺ cells from normal subjects ( P  = 0.55). MDS CD34⁺ blood cells also showed oxidized pyrimidine nucleotides compared with CD34⁻ cells ( P  = 0.029). Within normal subjects no differences were seen between CD34⁺ and CD34⁻ bone marrow cell compartments. CD34⁺ bone marrow cell oxidized pyrimidines were strongly associated with elevated plasma TNF-α and low bone marrow mononuclear cell glutathione concentrations (5/6 patients) and the inverse relationship was also found (3/4 patients). This data implies a role for intracellular oxygen free radical production, perhaps mediated by TNF-α, in the pathogenesis of ineffective haemopoiesis in MDS and provides a rationale for the bone marrow stimulatory effects of antioxidants such as Amifostine in MDS.     

Factors associated with successful mobilization of peripheral blood progenitor cells in 200 patients with lymphoid malignancies

Peripheral blood progenitor cells (PBPC) were mobilized and harvested in 200 patients treated for non-Hodgkin's lymphoma ( n  = 148), Hodgkin's disease ( n  = 22) and multiple myeloma ( n  = 30). The variables predicting the collection of a minimal (>2.5 × 10⁶/kg) or a high (>10 × 10⁶/kg) CD34⁺ cell count were analysed. Patients were mobilized with haemopoietic growth factors following either standard chemotherapy ( n  = 49) or high-dose cyclophosphamide, given alone ( n  = 55) or combined with high-dose VP16 ( n  = 86). 10 patients received haemopoietic growth factors only. The first mobilization resulted in a PBPC harvest with enough CD34⁺ cells in 179/200 patients (90%). High-dose cyclophosphamide, with or without VP16, did not mobilize a higher progenitor cell yield than standard chemotherapy. When performing multiple regression analysis in the 190 patients who received chemotherapy-containing mobilization, only the number of previous chemotherapy regimens and the exposure to fludarabine predicted for a failure to collect a minimal PBPC count ( P  = 0.06 and 0.0008 respectively). The target to collect a high CD34⁺ cell count was negatively associated with the number of previous chemotherapy regimens ( P  = 0.002). When only non-Hodgkin's lymphoma patients were considered for multivariate analysis, low-grade histology with fludarabine appeared to be associated with poor PBPC cell yield ( P  = 0.08 and 0.005 respectively). This data confirms that PBPC harvest should be planned early in the disease course in transplant candidates, and can be obtained after a standard course of chemotherapy.     

Sustained decrease of peripheral lymphocytes after allogeneic blood stem cell aphereses

48 healthy donors underwent peripheral blood stem cell (PBSC) apheresis for allogeneic transplantation beginning on day 4 of G-CSF (2 × 5 μg/kg) mobilization. In one to four (median two) large-volume mononuclear cell aphereses, a median of 55.9 × 10⁹ of lymphocytes (range 21.0–109.2 × 10⁹) were collected, an amount comparable to lymphocyte numbers removed by therapeutic lymphaphereses in autoimmune diseases. Mean peripheral lymphocyte counts decreased from premobilization values of 2.31 × 10⁹/l to 1.31 × 10⁹/l at a median of 34 d (1 month) and 1.53 × 10⁹/l at a median of 327 d (11 months). The decrease in peripheral lymphocyte counts was significantly correlated with the number of lymphocytes removed and the number of aphereses. Neutrophil and platelet counts returned to normal values after 1 month whereas monocyte counts and haemoglobin concentrations were significantly decreased at 1 month but not at 11 months.