Functional differences between dendritic cells derived from CD34+ bone marrow and peripheral blood stem cells

BACKGROUND AND OBJECTIVE: It has been previously demonstrated that dendritic cells (DCs) are characterized by an immature stage with high antigen internalization capacity, followed by a mature stage with predominantly immunostimulatory ability. The shift from the immature to the mature state can be induced in vitro by the addition of tumor necrosis factor-a (TNFa). The aim of our study was to investigate the maturation steps of DCs obtained from CD34(+) cells from peripheral blood stem cells (PBSC) and bone marrow (BM). DESIGN AND METHODS: DCs were generated in vitro from PBSC and BM CD34(+) selected cells. The endocytic activity of the cells was measured by means of dextran-FITC uptake and alloreactivity evaluated with mixed leukocyte reactions. Immunophenotypic analysis was performed by flow cytometry. RESULTS: We observed that DCs from PBSC, in contrast to the BM derived DCs, were never able to take up soluble antigens. Mixed leukocyte reactions (MLR) performed both on PBSC and BM CD34(+) derived DCs showed an allo-stimulatory activity comparable to normal controls at day 10, but significantly higher at day 14 after the addition of TNFa. Immunophenotypic analysis showed typical dendritic markers in all the samples and, after treatment with TNFa, enhanced expression of co-stimulatory molecules. INTERPRETATION AND CONCLUSIONS: Our data seem to indicate that, in our culture conditions, BM-derived DCs could be efficiently used for pulsing with specific peptides, while PBSC-derived DCs, being functionally mature, should be more suitable for gene therapy.     

A functional comparison of CD34 + CD38- cells in cord blood and bone marrow

We present cell cycling and functional evidence that the CD34+CD38- immunophenotype can be used to define a rare and primitive subpopulation of progenitor cells in umbilical cord blood. CD34+CD38- cells comprise 0.05% +/- 0.08% of the mononuclear cells present in cord blood. Cell cycle analysis with the fluorescent DNA stain 7- aminoactinomycin D showed that the percentage of CD34+ cells in cycle directly correlated with increasing CD38 expression. CD34+CD38- cord blood cells were enriched for long-term culture-initiating cells (LTCIC; cells able to generate colony-forming unit-cells [CFU-C] after 35 to 60 days of coculture with bone marrow stroma) relative to CD34+CD38- cells. In an extended LTCIC assay, CD34+CD38- cells were able to generate CFU-C between days 60 and 100, clearly distinguishing them from CD34+CD38+ cells that did not generate CFU-C beyond day 40. When plated as single cells, onset of clonal proliferation was markedly delayed in a subpopulation of CD34+CD38- cells; clones (defined as > 100 cells) appeared after 60 days of culture in 2.9% of CD34+CD38- cells. In contrast, 100% of CD34+CD38+ cells formed clones by day 21. Although the CD34+CD38- immunophenotype defines highly primitive populations in both bone marrow and cord blood, important functional differences exist between the two sources. CD34+CD38- cord blood cells have a higher cloning efficiency, proliferate more rapidly in response to cytokine stimulation, and generate approximately sevenfold more progeny than do their counterparts in bone marrow.     

Identification of human T-lymphoid progenitor cells in CD34+ CD38low and CD34+ CD38+ subsets of human cord blood and bone marrow cells using NOD-SCID fetal thymus organ cultures

In contrast to myeloid and B-lymphoid differentiation, which take place in the marrow environment, development of T cells requires the presence of thymic stromal cells. We demonstrate in this study that human CD34+, CD34+ CD38+ and CD34+ CD38(low) cells from both cord blood and adult bone marrow reproducibly develop into CD4+ CD8+ T cells when introduced into NOD-SCID embryonic thymuses and further cultured in organotypic cultures. Such human/mouse FTOC fetal thymic organ culture) thus represents a reproducible and sensitive system to assess the T-cell potential of human primitive progenitor cells. The frequency of T-cell progenitors among cord-blood-derived CD34+ cells was estimated to be 1/500. Furthermore, the differentiation steps classically observed in human thymus were reproduced in NOD-SCID FTOC initiated with cord blood and human marrow CD34+ cells: immature human CD41(low) CD8- sCD3- TCR alphabeta- CD5+ CD1a+ T cells were mixed with CD4+ CD8+ cells and more mature CD4+ CD8- TCR alphabeta+ cells. However, in FTOC initiated with bone marrow T progenitors, <10% double-positive cells were observed, whereas this proportion increased to 50% when cord blood CD34+ cells were used, and most CD4+ cells were immature T cells. These differences may be explained by a lower frequency of T-cell progenitors in adult samples, but may also suggest differences in the thymic signals required by bone marrow versus cord blood T progenitors. Finally, since cytokine-stimulated CD34+ CD38(low) cells retained their ability to generate T cells, these FTOC assays will be of value to monitor, when combined with other biological assays, the influence of different expansion protocols on the potential of human stem cells.     

Cell cycle and functional differences between CD34+/CD38hi and CD34+/38lo human marrow cells after in vitro cytokine exposure

The proliferation kinetics and clonogenic activity of CD34+/38hi (CD38hi) and CD34+/38lo (CD38lo) human marrow cells were measured before and after culturing the cells in vitro over a 6-day period in serum-deprived medium containing recombinant growth factors (interleukin-1 [IL-1], IL-3, IL-6, granulocyte colony-stimulating factor [G-CSF], granulocyte-macrophage [GM]-CSF, kit ligand, and erythropoietin). Before in vitro culture, 3% +/- 3% of the CD38lo and 13% +/- 2% of the CD38hi cells were in the S-phase of the cell cycle. The clonogenic activity of CD38hi cells was twofold greater than that of the CD38lo cells, as measured by colony-forming units (CFU) in short- term assays. However, CD38hi cells contained fewer pre-CFU than did the CD38lo cells, generating only 3 +/- 2 colonies per 1,000 cells after 4 weeks of culture on competent stromal layers, compared with 107 +/- 46 colonies per 1,000 cells from the CD38lo population. CD38hi and CD38lo cells exhibited distinctly different responses when cultured in serum- deprived medium supplemented with recombinant growth factors. After culturing cells for 24 hours, CD38lo cells essentially remained a noncycling population with only 5.1% +/- 3.0% of the cells cycling, whereas 44.2% +/- 6.9% of the CD38hi cells were in DNA synthesis. Gradually CD38lo cells were recruited into cycle, such that by 72 hours, approximately 28% of the CD38lo cells were in S-phase. However, during 6 days of culture, the percentage of cycling CD38lo cells never exceeded the proliferative response observed for CD38hi cells. Phenotype analysis conducted at day 6 indicated that 86% of the CD38hi population were no longer phenotypically CD34+/38hi, while 60% of CD38lo cells maintained a CD34+/38lo phenotype. Long-term cultures initiated with 6-day in vitro-expanded CD38lo cells showed approximately a twofold decrease in clonogenic activity attributable to a loss of erythroid precursors and a decrease in GM colonies. Thus, a proportion of CD38lo cells capable of generating CFU was maintained even after exposure to growth factors.     

Apoptotic bone marrow CD34+ cells in cirrhotic patients

AIM: To access the frequency and level of apoptotic CD34+ cells isolated from the marrow fluid of patients with post-hepatitis cirrhosis. METHODS: The frequency of bone marrow CD34+ cells and apoptotic bone marrow CD34+ cells in 31 inpatients with post-hepatitis cirrhosis (cirrhosis group), and 15 out-patients without liver or blood disorders (control group) was calculated by flow cytometry. Parameters were collected to evaluate liver functions of patients in cirrhosis group. RESULTS: The percentage of norm...     

Correlation of c-kit expression and cell cycle regulation by transforming growth factor-beta in CD34+ CD38- human bone marrow cells

To investigate the relationship between c-kit expression and cell cycle regulation by endogenous transforming growth factor-beta (TGF-beta) in human bone marrow hematopoietic progenitor cells, CD34+ CD38- c-kit(low/-) and CD34+ CD38- c-kit(high) populations were cultured in stem cell factor, thrombopoietin, interleukin-3 (IL-3), IL-6, granulocyte colony-stimulating factor, granulocyte/macrophage colony-stimulating factor and anti-TGF-beta, and analyzed for cell cycle status. Arrest in G0/G1 was most prominent in the precultured CD34+ CD38- c-kit(low/-) subset (95.62 +/- 4.15%). While postcultured CD34+ CD38- c-kit(high) cells initiated from CD34+ CD38- c-kit(high) cells entered cell cycle within 36 hr, postcultured CD34+ CD38- c-kit(low/-) cells initiated from CD34+ CD38- c-kit(low/-) cells remained dormant until 36 hr and entered cell cycle within 90 hr. Anti-TGF-beta increased the percentage of S/G2M phase postcultured CD34+ CD38- c-kit(high) cells (from 19.08 +/- 11.95 to 47.04 +/- 2.93%), but no significant change was observed in postcultured CD34+ CD38- c-kit(low/-) cells. These results suggest that endogenous TGF-beta plays an important role in the cell cycle arrest of c-kit(high) but not c-kit(low/-) cells in CD34+ CD38- cells, which proliferate without undergoing differentiation. The different regulatory mechanism of cell cycle entry of the CD34+ CD38- c-kit(high) and CD34+ CD38- c-kit(low/-) subsets might be the result of differences in their sensitivity to endogenous TGF-beta.     

骨髓CD34^＋干细胞向内皮细胞转化的诱导方法

目的探讨骨髓CD34^＋细胞向血管内皮细胞转分化的诱导方法。方法采集犬骨髓,经免疫磁珠分离出内皮祖细胞,内皮细胞生长因子（VEGF）诱导分化为内皮细胞并扩增,倒置相差显微镜、免疫细胞化学和摄取DilAc—LDL试验鉴定。将所得细胞种植于人工血管,扫描电镜观察细胞形态,并与MNCs作对比。结果经流式细胞仪测定,分离后的细胞中CD34^＋细胞占78．46％±6．37％;CD34^＋细胞培养2周后细胞基本铺满培养瓶底面,细胞呈“鹅卵石”状排列,CD34^＋和Ⅷ因子免疫细胞化学染色均为阳性。扫描电镜下观察可见内皮细胞平铺于人工血管表面,有伪足伸出并长入血管内表面微孔内。结论通过免疫磁珠方法可分离得到高纯度的骨髓CD34^＋细胞,经体外培养VEGF诱导后可定向分化为内皮细胞。     

Fas ligand promotes cell survival of immature human bone marrow CD34+CD38- hematopoietic progenitor cells by suppressing apoptosis.

Fas (CD95, APO-1) is a member of the TNF receptor family, and engagement of Fas by its ligand, Fas ligand (FasL), can induce apoptotic death of Fas expressing cells. Signaling through Fas has previously been shown to induce apoptosis of CD34+ human hematopoietic progenitor cells after exposure to IFN-gamma or TFN-alpha. In contrast, we found that FasL promoted a significantly increased viability of primitive CD34+CD38- cells. Thus, incubation with FasL for 48 hours reduced cell death from 46 to 29% compared to cells cultured in medium alone as measured by propidium iodide (PI) incorporation (n = 8, p < 0.02). Inhibition of apoptosis was confirmed by morphological analysis and by the Nicoletti technique. Furthermore, by using a delayed addition assay at the single cell level we found that sFasL treatment had a direct viability-promoting effect on CD34(+)CD38(-) cells. The effect of sFasL was completely blocked by NOK-1, a neutralizing mAb against FasL. In agreement with previous reports, FasL alone slightly increased cell death of more mature CD34(-)CD38+ cells, indicating an interesting shift in the responsiveness to FasL during early hematopoiesis.     

Hematopoietic capability of CD34+ cord blood cells: a comparison with CD34+ adult bone marrow cells

The characteristics of hematopoietic progenitor and stem cell (HPC/HSC) populations in mammals vary according to their ontogenic stage. In humans, HPC/HSCs from umbilical cord blood (CB) are increasingly used as an alternative to HPC/HSCs from adult bone marrow (BM) for the treatment of various hematologic disorders. How the hematopoietic activity of progenitor and stem cells in CB differs from that in adult BM remains unclear, however. We compared CD34+ cells, a hematopoietic cell population, in CB with those in adult BM using phenotypic subpopulations analyzed by flow cytometry, the colony-forming activity in methylcellulose clonal cultures, and the repopulating ability of these cells in NOD/Shi-scid (NOD/SCID) mice. Although the proportion of CD34+ cells was higher in adult BM than in CB mononuclear cells, the more immature subpopulations, CD34+ CD33- and CD34+ CD38- cells, were present in higher proportions in CD34+ CB cells. Clonal culture assay showed that more multipotential progenitors were present in CD34+ CB cells. When transplanted into NOD/SCID mice. CD34+ adult BM cells could not reconstitute human hematopoiesis in recipient BM, but CD34+ CB cells achieved a high level of engraftment, indicating that CD34+ CB cells possess a greater repopulating ability. These results demonstrated that human hematopoiesis changes with development from fetus to adult. Furthermore, CD34+ CB cells contained a greater number of primitive hematopoietic cells, including HSCs, than did adult BM, suggesting the usefulness of CD34+ CB cells not only as a graft for therapeutic HSC transplantation but also as a target cell population for ex vivo expansion of transplantable HSCs and for gene transfer in gene therapy.     

Combined transplantation of allogeneic bone marrow and CD34+ blood cells

Allogeneic peripheral blood progenitor cells (PBPCs) were transplanted after immunoselection of CD34+ cells. Two patient groups were studied: group I patients received immunoselected blood CD34+ cells and unmanipulated marrow cells from the same donor. Group II patients were given immunoselected blood and bone marrow (BM) CD34+ cells. One to 6 weeks before bone marrow transplantation (BMT), PBPCs from HLA- identical and MLC- sibling donors were mobilized with granulocyte colony-stimulating factor (G-CSF) (5 micrograms/kg twice daily subcutaneously) for 5 days. Aphereses were performed at days 4 and 5 of G-CSF application. CD34+ cells were separated from the pooled PBPC concentrates by immunoadsorption onto avidin with the biotinylated anti- CD34 monoclonal antibody 12.8 and then stored in liquid nitrogen. BM was procured on the day of transplantation. Patients were conditioned with either busulfan (16 mg/kg) or total body irradiation (12 Gy) followed by cyclophosphamide (120 mg/kg). Cyclosporin A and short methotrexate were used for graft-versus-host disease (GVHD) prophylaxis. After transplantation, all patients received 5 micrograms G-CSF/kg/d from day 1 until greater than 500 neutrophils/microL were reached and 150 U erythropoietin/kg/d from day 7 until erythrocyte transfusion independence for 7 days. Group I consisted of patients with acute myeloid leukemia (AML) (n = 2), chronic myeloid leukemia (CML) (n = 2), and T-gamma-lymphoproliferative syndrome and BM aplasia (n = 1). The patients received a mean of 3.3 x 10(6) CD34+ and 3.7 x 10(5) CD3+ cells/kg body weight of PBPC origin and 4.5 x 10(6) CD34+ and 172 x 10(5) cells/kg body weight of BM origin. Group II consisted of five patients (two AML, two CML, one non-Hodgkin's lymphoma). They received a mean of 3.3 x 10(6) CD34+ and 3.2 x 10(5) CD3+ cells/kg from PBPC and 1.4 x 10(6) CD34+ and 0.6 x 10(5) CD3+ cells from BM. A matched historical control group (n = 12) transplanted with a mean of 5.2 x 10(6) CD34+ and 156 x 10(5) CD3+ cells/kg from BM alone was assembled for comparison. In group I, the median time to neutrophil recovery to > 100, > 500, and > 1,000/microL was 12, 15, and 17 days, respectively. Patients from group II reached these neutrophil levels at days 13, 15 and 17 post BMT. Neutrophil recovery in the control patient group occurred at days 17, 18, and 20 respectively.(ABSTRACT TRUNCATED AT 400 WORDS)     

Effect of rhG-CSF on the mobilization of CD38 and HLA-DR subfractions of CD34+ peripheral blood progenitor cells

Several studies have demonstrated that both CD34+/CD38– and CD34+/HLA-DR- human hematopoietic progenitor cells have properties associated with hematopoietic stem cells. However, the kinetics of these two cell populations in human peripheral blood (PB) after priming with granulocyte colony-stimulating factor (rhG-CSF) has not been investigated. By using flow-cytometric analysis we have shown that administration of rhG-CSF to 14 patients eligible for peripheral blood progenitor cell (PBPC) transplantation led to an increment of CD34+/CD38+ and CD34+/HLA-DR+ cells in the PB that paralleled the increase of total CD34+ cells, indicating that such subpopulations are responsible for the major release of CD34+ cells. Furthermore, rhG-CSF priming led to a significant mobilization of fractions of more immature CD34+/CD38– and CD34+/HLA-DR- cells to the PB. In the leukapheresis preparations, the average frequency of CD34+ cells lacking the CD38 or HLA-DR antigens was low (5% and 30%, respectively), with little overlap between the CD38- and HLA-DR- subpopulations. In addition, the yield of each subset of CD34+ cells (CD34+/CD38± and CD34+/HLA-DR±) in the PB correlated with the numbers in the collected material. The results of the present study indicate that administration of rhG-CSF causes a significant increase of CD34+/CD38± and CD34+/HLA-DR± cells in PB, and that such cells can be then safely harvested by leukapheresis procedures.     

The generation of human natural killer cells from CD34+/DR- primitive progenitors in long-term bone marrow culture

We have adapted the stroma-dependent long-term bone marrow culture (LTBMC) system to study the development of human natural killer cells (NK) from the CD34+/HLA-DR- (CD34+/DR-) BM mononuclear cell (BMMNC) population. The CD34+/DR- population does not express any known antigens associated with myeloid or lymphoid lineage and has been shown by us and others to contain primitive hematopoietic progenitors capable of both self-renewal and differentiation to myeloid lineage. CD34+/DR- cells obtained from normal human BM by fluorescence-activated cell sorting were plated on allogeneic, irradiated BM stromal layers. After 5 weeks of culture in the presence of media containing recombinant interleukin-2 and human serum, 147- +/- 21-fold expansion of cells with the morphologic appearance of large granular lymphocytes was observed. Cultured cells (84.8% +/- 1.5%) expressed the characteristic CD56+/CD3- phenotype of NK. A proportion of CD56+/CD3- cells expressed other markers of lymphoid lineage that have been associated with mature NK, including CD2 (7.8% +/- 1.2%), CD7 (19.5% +/- 2.8), CD8 (3.1% +/- 1.0%), and CD16 (4.5% +/- 1.3%). The cultured cells did not express other antigens associated with T-lymphocyte (CD3, CD5, T-cell receptor [TCR] alpha/beta and TCR gamma/delta), B-lymphocyte (CD19), myeloid (MY8, CD33, and CD71), or monocytoid (CD14 and CD15) lineage and did not express the CD34 antigen associated with hematopoietic progenitors present on the starting population. This NK population was cytotoxic against both K562 (E:T 20:1; 79% +/- 1.9%) and Raji (E:T 20:1; 38% +/- 5.7%) target cell lines. The NK progenitor frequency in the CD34+/DR- cell population determined by limiting dilution of CD34+DR- on stromal layers followed by a functional chromium release assay against K562 targets was 1:169 +/- 50 CD34+/DR- cells. The data suggest that human LTBMC developed to study myeloid differentiation can be modified to study the origin and development of the NK and possibly other lymphoid lineages. Modified cultures show that cells with morphologic, phenotypic, and functional characteristics of NK can be derived from a population of BMMNC with the phenotype of primitive hematopoietic progenitors and without phenotypic evidence of lymphoid- or myeloid- lineage commitment. Further studies will address the cell of origin and the ontogeny of human NK and other lymphoid lineages.     

Replicative stress after allogeneic bone marrow transplantation: changes in cycling of CD34+CD90+ and CD34+CD90- hematopoietic progenitors

To further characterize hematopoietic "replicative stress" induced by bone marrow transplantation (BMT), the cell-cycle status of CD90+/- subsets of marrow CD34+ cells obtained 2 to 6 months after transplantation from 11 fully chimeric recipients was examined. Cycling profiles, derived by flow cytometry after staining with Hoechst 33342 and pyronin Y, were compared with those of 14 healthy marrow donors. Primitive CD34+CD90+ cells represented a smaller proportion of CD34+ cells in recipients (10% +/- 4% versus 19.6% +/- 5.3% in donors; P <.0001) and were more mitotically active, with the proportion of cells in S/G2/M nearly 4-fold higher than in donors (15.6% +/- 3% and 4.4% +/- 1.6%, respectively; P <.0001). By comparison, there was a modest increase in the proportion of CD34+CD90- progenitors in S/G2/M after BMT (10.9% +/- 1% vs 9.6% +/- 2% in donors; P =.04). Replicative stress after BMT is borne predominantly by cells in a diminished CD34+CD90+ population.     

Proliferation and differentiation of myelodysplastic CD34+ cells: phenotypic subpopulations of marrow CD34+ cells

In a search for a mechanism to explain the impaired growth of progenitor cells in patients with myelodysplastic syndromes (MDS), marrow CD34+ cells were purified up to 94.9% +/- 4.2% for normal individuals and 88.1% +/- 17.6% for MDS patients, using monoclonal antibodies and immunomagnetic microspheres (MDS CD34+ cells). Phenotypic subpopulations of these CD34+ cells were analyzed for CD38, HLA-DR, CD33, CD13, CD14, CD41 and CD3 plus CD19, in association with proliferative and differentiative capacities. The 15 studies performed included 12 MDS patients. Coexpression rate of CD13 significantly increased in the MDS CD34+ cell population with a value of 91.4% +/- 11.6% and ranging from 60.3% to 100%, and exceeded 99% in four studies, whereas that of normal CD34+ cells was 49.9% +/- 15.8%, ranging from 28.2% to 70.1% (P < .001). Coexpression rate of CD38, HLA-DR, CD33, CD14, and CD3 plus CD19 in MDS CD34+ cells did not significantly differ from that of normal CD34+ cells. The total number of colonies and clusters grown from 100 normal marrow CD34+ cells was 40.4 +/- 8.6, the range being from 27.2 to 50.3; this varied in MDS marrow CD34+ cells with a value of 34.0 +/- 28.7, the range being 0 to 95.9. The lineage of colonies and clusters promoted by MDS marrow CD34+ cells was predominantly committed to nonerythroid with impaired differentiation in 13 of 15 studies (87%). CD13 is first expressed during hematopoiesis by colony-forming unit granulocyte-macrophage and is absent in erythroid progenitors. Therefore, this study provides direct evidence for the lineage commitment of MDS CD34+ cells to nonerythroid with impaired differentiation and explains the mechanism of nil or low colony expression of MDS progenitor cells to erythroid lineage.     

Detection of cytomegalovirus DNA in CD34+ cells from blood and bone marrow

Infection of hematopoietic progenitor cells with the human cytomegalovirus (HCMV) has been proposed as an explanation for the cytopenias associated with HCMV-related disease. To test this hypothesis, CD34+ cells, which include the hematopoietic progenitors, as well as mature leukocyte populations were purified on a fluorescence- activated cell sorter and analyzed for HCMV DNA by polymerase chain reaction (PCR). A total of 33 samples from 31 immunosuppressed as well as immunocompetent HCMV-seropositive individuals were studied. CD34+ cells were PCR-positive in four of seven bone marrow aspirates from allogeneic bone marrow transplant recipients, in three of eight aspirates from patients with acquired immunodeficiency syndrome, and in the first of two bone marrow samples from an immunocompetent patient with primary HCMV disease. CD34+ cells purified from peripheral blood for autologous and allogeneic transplantation were also analyzed, and 4 of 13 samples were HCMV DNA-positive. Interestingly, two of the four HCMV-positive samples were from healthy allogeneic donors. Among the mature leukocyte populations, the monocytes were most frequently found to be HCMV DNA-positive. No HCMV DNA was detected in the total bone marrow leukocytes of 13 healthy seropositive bone marrow donors or in the CD34+ cell fraction of three further seropositive donors. In conclusion, the data provide strong evidence that CD34+ hematopoietic progenitor cells can be infected with HCMV in immunosuppressed patients, while this cell population was not identified as a major viral reservoir in healthy HCMV-seropositive individuals.     

Effect of bone marrow mesenchymal stem cells on the proliferation of bone marrow CD34~+ cells in vitro

Objective To investigate the effect on the marrow CD34+ cells by bone marrow mesenchymal stem cells(BMMSC),VarioMACS was used to sort bone marrow CD34+ cells,and then the purity of CD34+ cell was tested by FCM. Marrow mononuclear cells from abortion fetal bone marrow were isolated,and BMMSC were     

Apoptosis and proliferation differences between CD34+ and CD34- leukemic subpopulations in childhood acute leukemia

In view of the clinical and biological significance of leukemic heterogeneity we studied the efficacy of spontaneous apoptosis and cell cycle distribution in CD34+ and CD34 - leukemic subpopulations. Acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) leukemic samples with CD34 heterogeneous expression were separated into CD34+ and CD34 - fractions using fluorescence activated cell sorting. Cell cycle distribution, and apoptosis of the sorted subpopulations were estimated. CD34+ leukemic subpopulations had lower ability to apoptosis than that of CD34 - fractions in 6 out of 8 ALL samples and in 4 out of 5 AML samples. CD34+ fractions showed a higher percentage of proliferating cells compared to CD34 - cells in T-lineage ALL. These differences may lead to a more resistant phenotype of one of the subpopulations and reappearance this population in relapse.     

AA和MDS患者骨髓CD+34细胞及G-CSFR的表达及意义

目的检测再生障碍性贫血(AA)和骨髓增生异常综合征(MDS)患者骨髓CD+34细胞占单个核细胞(MNC)的比率及其表面粒细胞集落刺激因子受体(G-CSFR)的表达率,以探讨二者可能的发病机制.方法用流式细胞术(FCM)检测13例AA、22例MDS及12例非血液病患者骨髓CD+34细胞占MNC的比率及其表面G-CSFR的表达率.结果 AA组与对照组、AA组与MDS组、MDS-难治性贫血(RA)组与MDS-难治性贫血伴原始细胞增多(RAEB)组的骨髓MNC中CD+34细胞比率比较有显著性差异(P＜0.05),但G-CSFR的表达率比较无显著性差异(P＞0.05).大多数重型AA(SAA)患者(3/4)及很少慢性AA(CAA)患者(1/9)的骨髓MNC中CD+34细胞比率小于0.1%.大多数G-CSFR表达率低(＜14%)的MDS患者(7/9)外周血中性粒细胞减少;中性粒细胞减少在G-CSFR表达率正常(14%～28.9%)的患者(1/6)很少见;G-CSFR表达率高(＞28.9%)的患者(3/7)也存在中性粒细胞减少.结论骨髓CD+34细胞检测有助于判断AA患者病情及MDS患者的预后,亦可用于鉴别AA和MDS.