Evaluation of erythropoiesis after bone marrow transplantation: quantitative reticulocyte counting

Erythroid regeneration is an important and separate element in the engraftment process in allogeneic and autologous bone marrow transplantation (alloBMT, autoBMT). Qualitative visual reticulocyte counting has proved inadequate in the evaluation of erythropoiesis after BMT but automated flow cytometry now allows the reliable quantitation of reticulocytes even to very low levels. Reticulocyte counts and highly fluorescent reticulocyte (HFR) counts (very early reticulocytes) were estimated daily in recipients of 22 autoBMT and 14 alloBMT using a Sysmex R-1000 automated reticulocyte counter. Marrow ablation caused an immediate and rapid fall in both the reticulocyte count and the HFR. Measurable numbers of reticulocytes persisted throughout the hypoplastic period, but HFR fell to zero in the majority of both the autoBMT and alloBMT. HFR rose significantly after a median time of 14 d post-autoBMT, and 12 d post-alloBMT. Attainment of 15 x 10(9)/l reticulocytes and 0.5 x 10(9)/l HFR at day 21 post-transplant was associated with ultimate engraftment in 100% cases. Inadequate engraftment was seen in the majority of patients whose responses fell below these levels. Graft-versus-host disease was associated with a transient slight reduction in reticulocyte count. Neither episodes of infection nor blood transfusions had any significant impact on trends of reticulocytes or HFR. Automated flow cytometric reticulocyte counting has been shown to provide an accessible measure of erythroid activity which may be of predictive value in the management of patients following bone marrow transplantation.     

Flow cytometric reticulocyte quantification in the evaluation of hematologic recover

Abstract: The role of flow cytometric reticulocyte (RET) counting and the immature RET fractions (IRF) in the evaluation of hematopoietic recovery following chemoradiotherapy-induced aplasia was studied. RET counts and IRF were studied using an automated flow cytometric reticulocyte counter (Sysmex R-2000) in three groups of patients: 58 patients undergoing an autologous bone marrow transplantation (ABMT group), 28 of whom received granulocyte colony-stimulating factor (G-CSF); 28 patients undergoing an allogeneic bone marrow transplantation (BMT group); and 28 patients receiving remission-induction chemotherapy for acute leukemia (CHEMO group). To evaluate the IRF the percentages of RET fractions with middle and high fluorescence reticulocyte (MFR and HFR, respectively) were used. A rising IRF (expressed as the percentage of MFR ± HFR) was the first sign of hematopoietic recovery (ABMT group, IRF 9 days versus 18 days for the absolute neutrophil count (ANC); BMT group, 15 versus 18 days; CHEMO group, 9 versus 11 days). When recovery of the ANC (>0.5 times 109/1) was compared with that of the IRF (MFR ± HFR > 5%), statistically significant differences were found in all three groups. Additionally, 93.1% of the ABMT, 92% of the BMT and 91.2% of the CHEMO recovered the IRF before the ANC. In conclusion, an elevation in the percentage of IRF is the first sign of hematologic recovery in the majority of patients receiving remission-induction chemotherapy and the first sign of engraftment in those submitted to ABMT or BMT. Serial automated flow cytometric quantitative reticulocyte counting provides a useful and early measure of erythropoiesis indicative of hematopoietic reconstitution or successful bone marrow engraftment following marrow transplantation.     

Automated analyzer evaluation of reticulocytes in bone marrow and peripheral blood of hematologic disorders

The R-3000 reticulocyte analyzer uses flow cytometry with an argon laser as its light source. This analyzer stains residual RNA with auramine O to provide a reticulocyte maturation differential. Using the R-3000, we analyzed 119 samples of bone marrow (BM) and peripheral blood (PB) from 111 patients with hematologic disorders. Parameters were reticulocytes, immature reticulocyte fraction (IRF) percentage in BM and PB, BM/PB reticulocyte ratio, and BM/PB IRF ratio. Reticulocytes and IRF percentage in BM were significantly higher than in PB (p < 0.01). There was also a good correlation between reticulocyte percentages in BM and in PB (r = 0.81). Patients were classified into a normal group (without anemia) and an anemia group. Furthermore, the anemia group was classified into three groups: group 1: cases with hematopoietic dysfunction; group 2: cases in bone marrow recovery phase after chemotherapy and hematopoietic stem cell transplantation, and hematologic disorders with bone marrow accelerative phase, and group 3: cases with ineffective hematopoiesis (myelodysplastic syndrome). The mean reticulocyte percentage of the normal group was 2.3 +/- 1.1%, which was close to the normal value in BM. The BM/PB reticulocyte ratio of group 3 was statistically higher than that of groups 1 and 2. This indicates that group 3 had ineffective erythropoiesis and that the BM/PB ratio is a useful indicator for the diagnosis of myelodysplastic syndrome.     

The appearance of reticulocytes with medium or high RNA content is a sensitive indicator of beginning granulocyte recovery after aplasiogenic cytostatic drug therapy in patients with AML

Summary Flow-cytometric reticulocyte counts including their maturation status were performed during follow-up of induction (n=5) and consolidation (n=7) polychemotherapy in nine patients with acute myeloid leukemia (AML) using a Sysmex R-3000 automated counter. The reticulocytes fell to an extreme nadir (<0.01/pl) — as did leukocytes and platelets — and consisted of cells with low fluorescence ratio (LFR) only. After a median interval of 16 days, the fraction with medium fluoresence ratio (MFR) began to rise, preceding the reticulocytes with high fluorescence ratio (HFR) for a median of 1 day in all cases with partial (n=1) or complete (n=8) remission. At a median of 7 days after MFR and 5 days after HFR the granulocytes reached the critical limit of 0.5/nl. The reticulocytes rose to the normal range after 9 and 7 days, respectively. Automated flow-cytometric reticulocyte counting including the maturation status has been shown to provide an accessible measure of erythroid activity, which may be of predictive value for granulocyte recovery after aplasiogenic polychemotherapy in AML patients.Abbreviations HAM High-dose ara-C (cytarabine) plus mitoxantrone - DA daunorubicin plus ara-C - DAE DA plus etoposide - MAMAC amsacrine plus ara-C - TAD thioguanine plus ara-C plus daunorubicin Presented at the annual meeting of the German Society for Hematology and Oncology, 4–7 October 1992, BerlinFor the European Reticulocyte Count Working Group     

Assessment of hematologic progenitor engraftment by complete reticulocyte maturation parameters after autologous and allogeneic hematopoietic stem cell transplantation

BACKGROUND AND OBJECTIVES: Hematopoietic restoration after marrow ablation is initiated by the erythroid compartment. However, the absolute microscope counts or corrected percentage of reticulocytes have proven to be poor markers of hematopoietic engraftment. Some reports have highlighted the usefulness of automatic flow cytometry methods to determine highly fluorescent reticulocytes, or mean fluorescence index. In this series of 60 hematopoietic stem cell transplants, we sought the normal kinetics throughout the post-transplant period of the following reticulocyte maturing parameters: highly fluorescent reticulocytes (RETH), immature reticulocyte fraction (IRF), mean fluorescence index (MFI) and also mean reticulocyte volume (MRV). DESIGN AND METHODS: Sixty consecutive patients undergoing allogeneic bone marrow (30 cases) and autologous mobilized stem cell transplantation (30 cases) were studied. Parameters of reticulocyte maturation were measured every other day from the beginning of the conditioning regimen until myeloid engraftment. RESULTS: Nadir values for the analyzed reticulocyte parameters were found between days +4 and +7 and thereafter, increases in these reticulocyte parameters appeared earlier than the rise in neutrophils. We considered erythroid engraftment to have occurred on the day when RETH reached 3%, IRF 10%, MFI 10 and MRV 110 fL. These cut-offs were assigned considering the 25% quartile for each parameter on the day that the myeloid engraftment occurred. The median engraftment days for RETH were +9 and +16, for IRF +9 and +13, for MFI +9 and +13 and for MRV +11 and +13 in autologous and allogeneic procedures, respectively. When compared to standard neutrophil engraftment, IRF and MFI engraftment occurred significantly earlier in all patients. Remarkably, we found a statistical correlation between the day a reticulocyte parameter reached its cut-off and the subsequent day of absolute neutrophil count (ANC) recovery for MFI after allogeneic transplants and for MRV after autologous procedures (p < 0.001 and p= 0.02, respectively). Of all the clinical parameters tested, only the number of infused CD34 cells showed a statistical influence on erythroid engraftment in autologous transplant. INTERPRETATION AND CONCLUSIONS: Early reticulocytes appear sooner than neutrophils after both autologous and allogeneic transplants, and any determined reticulocyte parameter can reliably measure this fraction. Nevertheless, our results show that MRV and MFI cut-offs are useful for determining subsequent myeloid engraftment. These findings could be relevant to decision-making in those patients with primary graft failure heralded by an absence of increasing values of MFI and MRV, indicating very low production of reticulocytes from the graft, who could, therefore, benefit from earlier rescue therapy.     

Reticulocyte maturity pattern analysis as a predictive marker of erythropoiesis in paediatrics. Part II: pilot study for clinical application

Summary. Reticulocyte quantification in peripheral blood samples is a commonly used diagnostic indicator of erythropoietic activity. A methodology based on flow cytometry additionally separates reticulocytes into 3 groups by fluorescence staining of the residual RNA. This identifies cells as‘high (HFR), medium (MFR) and low (LFR) fluorescence intensity’reticulocytes. In Part II of the study we looked for the clinical applicability in paediatrics. Selected groups of patients with ineffective erythropoiesis, i.e. suffering from renal failure, oncologic patients with suppressed bone marrow activity caused by chemotherapy and anaemic new-born infants have been observed longitudinally for their reticulocyte maturity profiles. Data were compared to the commonly used parameters RBC, Hb and Hct. In all cases in which effective erythropoiesis returned documented by a normalization of standard blood parameters, HFR cells reacted significantly earlier than the traditional markers. These preliminary observations suggest the reticulocyte maturity pattern analysis can be used as an additional aid in diagnosis and as a helpful parameter for the monitoring of any anaemic situation.     

Increase of high fluorescence reticulocytes indicates mobilization of peripheral stem cells in children recovering from aplasia after chemotherapy or bone marrow transplantation

Enumeration of CD34 + cells is the standard assay procedure for optimization of peripheral blood stem cell harvesting. High fluorescence reticulocytes (HFR) have been shown to signal a rebound in haematopoiesis after chemotherapy. The aim of this study was to evaluate HFR determination, as compared to CD34 + cell counts and CFU-GM, as a potential predictor of PBSC counts after recovery from chemotherapy and/or bone marrow transplantation. Twenty-five paediatric patients undergoing intensive courses of chemotherapy and 9 undergoing bone marrow auto or allografts were investigated. In most of our cases, HFR recovered at the same time or earlier than CD34 + cells. Similarly, the rise in HFR preceeded the CFU-GM peak in most of these cases. In no case did we observe a CFU-GM peak without a rise in HFR%. In our experience, the daily relative HFR increase may be used to predict the optimal time for mobilization of stem cells and was therefore of value clinically to confirm the timing of apheresis.     

Highly fluorescent reticulocyte count predicts haemopoietic recovery after immunosuppression for severe aplastic anaemia

Highly fluorescent reticulocyte (HFR) counts are the most reliable and sensitive index of haemopoietic recovery after bone marrow or peripheral blood stem cell transplantation. We report the behaviour of HFRs during haemopoietic recovery in two patients who were affected by severe aplastic anaemia (SAA) and treated with horse antithymocyte globulin (ATG), cyclosporin A (CsA) and granulocyte colony-stimulating factor (G-CSF). A HFR value > 5% of the total reticulocyte count, a reticulocyte count > 30 x 10(9)/l, and a polymorphonuclear (PMN) count > 0.5 x 10(9)/l were found after 9 and 8, 20 and 46, and 16 and 22 days, respectively, after the end of ATG. HFR recovery to > 5% anticipated the rise of PMN > 0.5 x 10(9)/l by at least 7 and 14 days, respectively. Thus, HFR evaluation could be used as a reliable and early marker of response to immunosuppression in severe aplastic anaemia.     

Reticulocyte counts in the aged

Reticulocytes were measured on an automated reticulocyte counter in five groups; healthy adults, non-elderly patient with low hematopoiesis, adults with anemia, healthy elderly persons and elderly patients with anemia. The reticulocyte percent, absolute reticulocyte count, and reticulocyte composition as classified by fluorescence intensity (highly, moderately, and slightly fluorescent cells) were calculated. The healthy adults had a reticulocyte count of 0.70 +/- 0.55%, an absolute reticulocyte count of 4.36 +/- 1.90 X 10(4)/microliters, 2.33 +/- 1.95% highly fluorescent cells, 18.73 +/- 5.07% of moderately fluorescent cells, and 78.82 +/- 6.55% of slightly fluorescent cells. Patients with low hematopoiesis had lower counts except for the percentage of slightly fluorescent cell. Aged persons without anemia showed no differences in reticulocytes from healthy adults. However, elderly patients with anemia had a low reticulocyte count; there was no tendency towards an increase in the percentage of highly fluorescent cells or a decrease in the percentage of slightly fluorescent cells. Their reticulocyte percent was not significantly higher than healthy controls, suggesting that anemia observed in the aged arises from low hematopoietic activity in the bone marrow.     

The Maturation Rate of Reticulocytes

An in vitro culture technic for the study of reticulocyte maturation wasdescribed. The method gave reproducible results and proved to be of valuein the comparative study of reticulocyte maturation in blood disorders. By thismethod it was shown that variations in the reticulocyte maturation in vitroparalleled similar variations present in vivo.

The maturation of reticulocytes from patients with different types ofanemia was investigated. In some anemias the in vitro maturation of reticulocytes was prolonged, not only because younger reticulocytes were present inthe blood, but also because the rate at which the reticulum substance disappeared was delayed. This was particularly evident in the anemia of chronicuremia, in Cooley’s anemia and in pernicious anemia in relapse. In only occasional cases of hereditary spherocytosis and of autoimmune hemolyticanemia was the rate of reticulocyte maturation found to be moderatelydelayed. In patients with iron deficiency anemia or bleeding anemia it wasalways normal.

From the above findings the following conclusions were derived:

1. The reticulocyte number in the circulating blood is the resultant of threevariables: (a) the rate of output of new reticulocytes from the bone marrow;(b) the stage of maturation at which reticulocytes are delivered into theperipheral circulation; (c) the rate of disappearance of the reticulum substance.

2. The number of reticulocytes in the circulating blood cannot be indiscriminately used as a precise index of red cell production in erythrokinetics.

3. There is good reason to believe that a defect in the rate at which thereticulocytes mature in the circulating blood is an index of a similar defectin the process of erythroblastic differentiation in the bone marrow.

     

骨髓间充质干细胞联合肝细胞生长因子对心肌梗死治疗作用的实验研究

目的研究经非梗死相关动脉注入骨髓间充质干细胞(BMMSCS)联合肝细胞生长因子移植对心肌梗死的治疗作用。方法苏中幼猪18头,分为三组:单纯治疗组,联合治疗组及对照组,三组均经开胸结扎冠状动脉前降支制作心肌梗死模型,两组治疗组结扎后2周抽取骨髓分离培养骨髓间充质干细胞,并在结扎后4周经非梗死相关动脉注入梗死心肌(剂量5×106/ML),联合组同时注入肝细胞生长因子(HGF,4×109PFU),对照组则注入同样量的细胞培养液(IMDM);两组均在结扎后4周和8周行冠状动脉造影与门控心肌显像评价侧支循环和心功能,并在8周处死动物,取心脏标本,行免疫组化检查。结果(1)免疫组化结果显示:在两组治疗组与对照组梗死周边区均可见新生血管,但两组治疗组的新生血管密度高于对照组(P<0.05)。(2)门控心肌显像:治疗前两组治疗组与对照组LVEF无明显区别,无统计学意义(P>0.05);治疗后两组治疗组LVEF明显优于对照组,有统计学意义(P<0.05);两治疗组治疗前后LVEF明显好转(P<0.05),对照组前后LVEF无明显变化(P=0.035)。(3)冠状动脉造影显示:三组治疗前后侧支循环级别无统计学意义。结论经非梗死相关动脉BMMSCS联合肝细胞生长因子移植能够促进梗死心脏心功能改善和促进血管再生,但不能促进侧支血管的生成;同时联合治疗效果并不优于单纯干细胞治疗。     

In vitro maturation of nascent reticulocytes to erythrocytes

Most studies of mammalian reticulocyte maturation have used blood reticulocytes.Nascent reticulocytes, as found in bone marrow, have not been available in developmentally synchronized populations. Nascent murine reticulocytes formed in vitro by enucleation of Friend virus-infected erythroblasts were purified and recultured for 110 hours. At 0 hours, all recultured cells were lobulated and contained dense, centralized reticulin. By 110 hours, about 20% to 25% of the cells became biconcave erythrocytes. Most ribosomes and cellular RNAs were degraded within 20 hours, and during that period, heme synthesis declined from a rate equal to that of late erythroblasts to less than 10% of that rate. Many mitochondria appeared normal until they showed outer membrane swelling, degradation, and apparent fusion with intracellular vacuoles at 40 hours of culture. During the period of mitochondrial loss, Bcl-X(L), an antiapoptotic protein that accumulates during erythroblast differentiation and maintains mitochondrial membrane integrity, demonstrated progressive decreases and changes consistent with deamidation. Nevertheless, the reticulocytes did not undergo apoptosis, because their apoptotic machinery was degraded. This experimental system that provides a developmentally synchronized population of nascent murine reticulocytes that mature into biconcave erythrocytes in vitro should be useful in further investigations of the cellular events involved in reticulocyte maturation.     

Utility of flow cytometric reticulocyte quantification as a predictor of engraftment in autologous bone marrow transplantation

Flow cytometric reticulocyte quantification with thiazole orange (TO) was used to study erythropoiesis in 20 patients following autologous bone marrow transplantation for the treatment of acute myelogenous leukemia. Flow cytometric reticulocyte analysis provided not only the reticulocyte percentage and absolute reticulocyte count but a quantitative reticulocyte maturity index (RMI) proportional to the amount of RNA in the reticulocytes. The RMI values, but not the reticulocyte percentage or absolute counts, correlated temporally with the rise in the absolute neutrophil counts in the posttransplantation period. In the majority of patients (12/20), the RMI value was the earliest indicator of bone marrow engraftment. The findings of this study demonstrate an important clinical utility of TO reticulocyte analysis by flow cytometry and indicate the diagnostic importance of the RMI measurement in the evaluation of erythropoietic activity in bone marrow transplant patients.     

Autologous stem cell transplantation: evaluation of erythropoietic reconstitution by highly fluorescent reticulocyte counts, erythropoietin, soluble transferrin receptors, ferritin, TIBC and iron dosages

The plasma concentrations of erythropoietin (Ep), soluble transferrin receptors (sTfRs), iron, total iron binding capacity (TIBC) and ferritin were monitored in five leukaemia patients undergoing autologous bone marrow stem cell transplantation (BMSCT) and in 10 lymphoma and 21 ovarian cancer patients undergoing autologous peripheral blood SCT (PBSCT); 9/21 ovarian cancer patients received recombinant human G-CSF and Ep and six recombinant human GM-CSF and Ep following SCT. All parameters were evaluated in relation to the kinetics of erythroid reconstitution as evaluated by haemoglobin (Hb) and reticulocyte levels [including the fraction of immature reticulocytes, also called highly fluorescent reticulocytes (HFR)].
Leukaemia patients undergoing BMSCT showed only a delayed (occurring at days 35–50 after SCT) and partial RBC, neutrophil and platelet recovery, whereas all patients undergoing PBSCT exhibited a rapid (occurring at days 10–15 after SCT) and sustained haemopoietic recovery. The various levels of erythroid rescue observed among these patients markedly influenced the kinetics of the different parameters investigated: (i) in leukaemia BMSCT patients sTfRs declined following SCT and remained at low levels thereafter, whereas Ep, iron, TIBC and ferritin showed a progressive and significant increase; (ii) in the different groups of patients undergoing PBSCT: (a) sTfR levels first declined following SCT and then returned to pre-therapy values at days 12–16, this response preceded erythropoietic recovery; (b) Ep, total iron, TIBC and ferritin showed an initial increase in the first days following SCT and then returned to pre-therapy values.
Altogether, these observations indicate that: (i) both sTfR levels and reticulocyte counts are predictive parameters of erythropoietic recovery; (ii) coordinated changes of biochemical parameters underlying iron metabolism (iron, TIBC and ferritin) accompany erythroid rescue following SCT.     

Simultaneous measurement of reticulocyte and red blood cell indices in healthy subjects and patients with microcytic and macrocytic anemia

Using the new Bayer H*3 hematology analyzer (Leverkusen, Germany), we have determined red blood cell and reticulocyte indices in 64 healthy subjects, in patients with microcytosis due to iron deficiency (58 patients) and heterozygous beta-thalassemia (40 patients), and in patients with macrocytosis (28 patients). We found in all cases that reticulocytes were larger than mature red cells by 24% to 35%, with a hemoglobin concentration 16% to 25% lower and a similar hemoglobin content. The correlation between red cell and reticulocyte indices was strikingly tight (r = .928 for volume, r = .929 for hemoglobin concentration, r = .972 for hemoglobin content) in all four groups, regardless of red blood cell size. The ratio of reticulocyte to red blood cell mean corpuscolar volume (MCV ratio) was constantly above 1. Inversion of the MCV ratio was observed only in four patients. It was always abrupt and transitory and was associated with erythropoietic changes leading to the production of red blood cells of a different volume (treatment of megaloblastic anemia, functional iron deficiency, bone marrow transplantation). In two cases of marrow transplantation, reticulocyte volume fell during the aplastic phase after conditioning chemotherapy and then rapidly increased up to values higher than before; this production of macroreticulocytes was the earliest sign of engraftment.     

Bone marrow transplantation for acute nonlymphocytic leukemia in first remission: analysis of prognostic factors

Prognostic factors were reviewed retrospectively for 39 children and adults aged 1 to 40 years (median 14 years) with acute nonlymphocytic leukemia (ANLL) who attained a first remission and underwent bone marrow transplantation from November 1976 to July 1983. The preparation regimen for transplantation was cyclophosphamide (60 mg/kg/d for two days) followed by total body irradiation (either 750 cGy single dose at 26 cGy/min, n = 37, or 1,320 cGy fractionated at 10 cGy/min, n = 2). Twenty-three patients are surviving disease free with a median followup of three years. The three-year estimated disease-free survival is 55% +/- 17% (+/- 2 SE). Five patients have relapsed from 92 to 756 days after transplantation for an estimated relapse rate of 21% +/- 18%. Two factors, the white blood cell (WBC) count and the French-American-British (FAB) classification at leukemia diagnosis were found to be of prognostic importance. Patients with a WBC of less than 20,000/microL at diagnosis had a three-year estimated disease-free survival of 74% +/- 18% v 26% +/- 24% for those with a WBC of greater than or equal to 20,000 (P = .008). The estimated relapse rate was 6% +/- 12% for patients with a WBC at diagnosis less than 20,000 v 53% +/- 38% for patients with a WBC at diagnosis of greater than or equal to 20,000 (P = .01). Patients with myeloid morphology at diagnosis (FAB M1,2,3) had an estimated relapse rate of 9% +/- 12% v patients with monocytoid morphology (FAB M4,5a) whose estimated relapse rate was 58% +/- 44% (P = .05). Our data suggest that a high WBC count at poor prognostic factors for patients with ANLL who undergo bone marrow transplantation in first remission after conditioning with cyclophosphamide plus total body irradiation.     

Effect of altering administration order of busulphan and cyclophosphamide on the myeloablative and immunosuppressive properties of the conditioning regimen in mice

OBJECTIVE: The present study was designed to investigate the influence of the administration sequence of busulphan (Bu) and cyclophosphamide (Cy) during conditioning regimen on myeloablative and immunosuppressive effects and on engraftment. METHODS: Female Balb/C mice were treated with either Bu-Cy or Cy-Bu (assigned order of administration). Bu was administered as 8.75 mg/kg/day x 4 and Cy as 100 mg/kg/day x 2. The control consisted of untreated animals. Bone marrow and spleen were harvested during the conditioning regimen and for up to 19 days after treatment. Colony-forming unit granulocyte macrophage assay was performed on marrow cells. Immunological analyses were performed using spleen cells. Liver status was determined using aspartate amino transferase (AST), alanine amino transferase (ALT), and bilirubin. Animals assigned for engraftment study were conditioned as above and transplanted using sca-1 cells from male Balb/C donors. Engraftment was followed using fluorescence in situ hybridization up to 30 days posttransplantation. RESULTS: No significant difference in myeloablative effect was observed between treatments. Immunosuppressive activity expressed as CD3+/CD19+ and CD4+/CD8+ was also similar. Levels of cytokines interleukin 2, tumor necrosis factor alpha, and interferon gamma at the end of the conditioning regimen were lower in the Cy-Bu group, while liver enzymes were higher after the Bu-Cy regimen. Engraftment in bone marrow was reached faster within the first 20 days after conditioning with Cy-Bu compared to Bu-Cy. However, no difference in chimerism was observed at 30 days. CONCLUSION: Cy-Bu treatment resulted in lower levels of cytokines, faster bone marrow engraftment, and lower values of liver enzymes compared to Bu-Cy regimen, which may benefit stem cell transplantation outcomes.     

Evaluation of the Abbott Cell Dyn 4000 automated fluorescent reticulocyte measurements: comparison with manual,FACScan and Sysmex R1000 methods

The Abbott Cell Dyn 4000 (CD4000) is the first haematology analyser in which fully-automated reticulocyte measurements can be routinely determined by fluorescence as part of the full blood count. This communication reports the first evaluation of this method which was undertaken by three independent reference laboratories in Belgium, Germany and Italy. A total of 695 different samples was entered into the study which was designed to compare CD4000 reticulocyte information (enumeration and qualitative maturational data) with results determined in parallel with the existing manual (supravital staining) reference procedure, and two semi-automated fluorescent assays (Becton Dickinson FACScan and Sysmex R1000 instruments). These studies revealed good agreement between the CD4000 and the manual procedure, with no inter-method bias. Comparison of CD4000 and FACScan reticulocyte measurements, however, indicated a distinct tendency for the FACScan to give higher reticulocyte estimates than the CD4000. Finally, the comparison of the CD4000 with the Sysmex R1000 showed excellent agreement in the range 0–6% reticulocytes, although there was some inter-method bias in the higher range (>15%). Analysis of agreement levels between the methods using specific ‘clinical decision points’ confirmed the tendency for overestimation by the FACScan, in that 58% of the samples with a reticulocytopenia of <0.5% as defined by the CD4000 gave FACScan results within the normal range (0.5–1.8%). In contrast, there was absolute agreement between the CD4000 and the SysmexR1000 for all reticulocytopenias. Comparison (195 samples) of instrument fluorescentreticulocyte maturation profiles demonstrated an exponential relationship (r = 0.78) between CD4000 IRF and R1000 HFR (highly fluorescent reticulocyte fraction) values. The suggestion that the CD4000 IRF values includes some of the MFR as well the HFR reticulocyte fraction was confirmed as the correlation between the CD4000 IRF and the Sysmex R1000 MFR plus HFR percentages was linear (r = 0.82). This study confirms a high performance level for the CD4000 automated fluorescent reticulocyte method.     

Optimal timing of repeated rh-erythropoietin administration improves its effectiveness in stimulating erythropoiesis in healthy volunteers

We studied the effect of recombinant human erythropoietin (rhEPO) on erythropoiesis when given at different time intervals to healthy adults. 15 volunteers were randomly selected to receive rhEPO (2×300 U/kg) and parenteral iron (2×200mg) either within a 24 h or 72 h interval. Controls received parenteral iron only. Maximum EPO levels were found 24 h after the first intravenous injection (day 1) with a mean value of 364 and 390 U/l for the rhEPO-treated groups. When second rhEPO administration was after 72 h (group III), volunteers showed significantly higher absolute reticulocyte counts and a higher percentage of young RNA-rich reticulocytes (HFR ratio) over several days compared to those who received rhEPO within a 24 h interval (group II). Both rhEPO-treated groups showed an increase in the mean reticulocyte cell volume. Reticulocyte haemoglobin concentration was inversely correlated with the increasing cell size with a nadir on day 8. Reticulocyte haemoglobin content showed a significant decrease in group II after day 5. Serum ferritin levels showed an inverse pattern to the rate of erythropoiesis. After an initial rise, the serum ferritin decrease was most pronounced in group III. Contrary to previous reports with oral iron supplementation, functional iron deficiency was not seen during rhEPO stimulation, due to parenteral iron administration. Our data suggest that the time interval between repeated administrations of rhEPO has an important influence on its pharmacodynamics. rhEPO given within an interval of 72 h was more effective in stimulating erythropoiesis than administration within a 24 h interval for the same total dose.     

Acute lymphoblastic leukemia in childhood treated with non-T-cell depleted bone marrow transplantation from an HLA 2 loci (HLA-A and-DRB1)-mismatched mother after early graft failure of cord blood transplantation

An 11-year-old boy with acute lymphoblastic leukemia received unrelated cord blood transplantation at the second remission. Because of early graft failure, he was given a second non-T-cell depleted bone marrow transplant from his HLA 2 loci (HLA-A and -DRB1)-mismatched mother 36 days after the first transplantation. Feto-maternal microchimerism was verified before transplantation. The second transplantation was performed with fludarabine/melphalan as a conditioning regimen, and tacrolimus/short-course methotrexate as graft-versus-host disease (GVHD) prophylaxis. Engraftment was prompt with a recovery of neutrophils (> 0.5 x 10(9)/1) by day +10, reticulocytes (> 1%) by day +17 and platelets (> 50 x 10(9)/l) by day +18. Mild regimen-related toxicities (grade I gastrointestinal, grade II hepatic) were observed and acute GVHD was grade I (skin: stage 2). No severe complication was noted. At 6 months post-transplantation, he had no chronic GVHD or leukemia relapse. This experience indicates the future feasibility of a back-up non-T-cell depleted transplantation from HLA 2 loci-mismatched and feto-maternal microchimerism-positive mothers in cases with primary graft failure.