Generation of antigen-presenting cells for soluble protein antigens ex vivo from peripheral blood CD34+ hematopoietic progenitor cells in cancer patients

Peripheral blood CD34⁺ hematopoietic progenitor cells (PBPC) mediate hematopoietic reconstitution in cancer patients after autologous transplantation and can be expanded ex vivo in the presence of colony-stimulating factors. This study shows that functionally active antigen-presenting cells (APC) for soluble proteins are generated and expanded in these PBPC cultures. CD34⁺ cells were cultured ex vivo in medium containing stem cell factor, interleukin-1β (IL-1β), IL-3, IL-6, and erythropoietin (EPO). The cells from these cultures developed into very potent APC of tetanus toxid and purified derivative of tuberculin for autologous T cells in vitro. The antigen-presenting capacity of these cells was maintained for at least 38 days of culture. These APC resembled immature cells of the myelomonocytic cell lineage by surface marker, immunocytochemistry and ultrastructural analysis. Such APC might be able to present antigens from certain tumors to the immune system.     

Rhodamine 123 efflux in human subpopulations of hematopoietic stem cells: comparison between bone marrow, umbilical cord blood and mobilized peripheral blood CD34+ cells

Hematopoietic stem cells (HSC) can be identified by the expression of the CD34 molecule. CD34+ cells are found in bone marrow (BM), umbilical cord blood (UCB) and in mobilized peripheral blood (PB). CD34+ cells express P-glycoprotein (Pgp), a product of the multidrug resistance (MDR) gene. Pgp activity can be measured by the efflux of the dye Rhodamine 123 (Rho 123) and can be blocked by verapamil. Transport activity in HSC suggests that Pgp could have a functional role in stem cell differentiation. This study compared the number of CD34+ cells with Pgp activity measured by efflux of Rho 123 in the hematopoietic population obtained from different sources. Samples were analysed for their content of CD34+ cells, and BM had a significantly higher amount of CD34+ cells compared to UCB, mobilized PB and normal PB. When the frequency of Rholow cells was studied among the CD34+ population, an enrichment of cells with Pgp activity was observed. The frequency in BM was significantly lower than that in UCB and mobilized PB. The low retention of Rho 123 could be modified by verapamil, indicating that the measurements reflected dye efflux due to Pgp activity. Although UCB and mobilized PB had a lower number of CD34+ cells compared to BM, the total number of CD34+ cells with Pgp activity was similar in the three tissues. The different profiles may indicate the existence of subpopulations of stem cells or different stages of cellular differentiation detected by the extrusion of the dye Rho 123.     

Suppression of natural killer cells in the presence of CD34+ blood progenitor cells and peripheral blood lymphocytes.

Abstract Mobilization of CD34 + peripheral blood progenitor cells (PBPCs) with granulocyte-colony stimulating factor (G-CSF) may induce functional alterations in peripheral blood lymphocyte (PBL) subsets. We and others have shown that natural killer (NK) cells from PBPC collections are less expandable in vitro than those obtained during steady-state hematopoiesis. We show here that the extent of this proliferation deficit is related to the number of circulating CD34 + cells in vivo at the time of PBPC apheresis. Likewise, addition of autologous CD34 + cells to unseparated PBL reduced the expansion of the NK-cell subset by 22.2% +/- 6.0% (n = 10; P <.005). In contrast, when using purified NK cells, their proliferation remained unimpaired by autologous CD34 + cells. Supernatants from CD34 + cells cultured with autologous PBLs had an inhibitory effect on proliferation of purified NK cells (n = 16; P =.03), indicating that an interaction between CD34 + cells and lymphocytes is essential for the suppressive effect on NK cells. To investigate the role of T cells in this interaction, intracellular cytokines were determined in T cells cultured for 7 days with or without autologous CD34 + cells. When cultured with CD34 + cells, the frequency of IL-2-producing CD4 + and CD8 + T cells was reduced by 19% and 24%, respectively, compared with T cells cultured alone (n = 7; P =.016). Interferon-gamma-producing T cells were slightly reduced ( P = not statistically significant [ns]). Finally, the influence of T cells and NK cells on the recovery of myeloid colony-forming cells (CFU-GMs) from purified CD34 + cells was examined. In the presence of T cells, 16% +/- 6% of the input CFU-GM recovered after 7 days, compared with 5% +/- 4% in the presence of NK cells (n = 5; P = ns). Our findings point to an inhibition of NK-cell proliferation mediated by an interaction of CD34 + cells and T cells occurring during PBPC mobilization with G-CSF.     

Plasma levels of SDF-1 and expression of SDF-1 receptor on CD34+ cells in mobilized peripheral blood of non-Hodgkin's lymphoma patients

CXCR4 is the receptor for the chemokine stromal derived factor-1 (SDF-1), is expressed on CD34+ cells, and has been implicated in the process of CD34+ cell migration and homing. We studied the mobilization of CD34/CXCR4 cells and the plasma levels of SDF-1 and flt3-ligand (flt3-L) in 36 non-Hodgkin's lymphoma patients receiving cyclophosphamide (Cy) plus G-CSF (arm A), Cy plus GM-CSF (arm B), or Cy plus GM-CSF followed by G-CSF (arm C) for peripheral blood stem cell (PBSC) mobilization and autotransplantation. We observed lower plasma levels of SDF-1 in PBSCs compared to premobilization bone marrow samples. The mean plasma SDF-1 levels were similar in PBSC collections in the three arms of the study. In contrast, SDF-1 levels in the apheresis collections of the "good mobilizers" (patients who collected a minimum of 2 x 10(6) CD34+ cells/kg in one to four PBSC collections) were significantly lower than the apheresis collections of the "poor mobilizers" (> or = 0.4 x 10(6) CD34+ cells/kg in the first two PBSC collections; 288 +/- 82 pg/ml versus 583 +/- 217 pg/ml; p = 0.0009). The mean percentage of CD34+ cells expressing CXCR4 in the apheresis collections was decreased in the PBSC collections compared with premobilization values from 28% to 19.4%. Furthermore, the percentage of CD34+ cells expressing CXCR4 in the good mobilizers was significantly lower compared with the poor mobilizers (14.7 +/- 2.1% versus 33.6 +/- 2.1%; p = 0.002). The good mobilizers had also significantly lower levels of flt3-L compared with the poor mobilizers (34 +/- 4 pg/ml versus 106 +/- 11 pg/ml; p = 0.006), Finally, the levels of flt3-L strongly correlated with SDF-1 levels (r = 0.8; p < 0.0001). We conclude: A) low plasma levels of SDF-1 and low expression of CXCR4 characterize patients with good mobilization outcome, and B) the levels of SDF-1 correlate with flt3-L, suggesting an association of these cytokines in mobilization of CD34+ cells.     

Comparison of CD34 and monocyte-derived dendritic cells from mobilized peripheral blood from cancer patients

Dendritic cells (DCs) are potent antigen-presenting cells that are integral to the initiation of T-cell immunity. Two cell types can be used as a source for generating DCs: monocytes and CD34(+) stem cells. Despite many investigations characterizing DCs, none have performed a direct paired comparison of monocyte and stem cell-derived DCs. Therefore, it is unclear whether one cell source has particular advantages over the other, or whether inherent differences exist between the two populations. We undertook the following study to determine if there were any differences in DCs generated from monocytes or CD34(+) cells from mobilized peripheral blood. DCs were generated by culturing the adherent cells (monocytes) in interleukin-4 and GM-CSF for 7 days, or by culturing nonadherent cells (CD34(+)) in the presence of GM-CSF and tumor necrosis factor alpha for 14 days. The resulting DCs were compared morphologically, phenotypically, functionally, and by yield. We could generate morphologically and phenotypically similar DCs. Differences were encountered when expression levels of some cell surface markers were examined (CD86, HLA-DR). There was no difference in how the DCs performed in a mixed lymphocyte reaction (p = .3). Further, no statistical difference was discovered when we examined cellular (DC) yield (p = .1); however, there was a significant difference when yield was normalized to the starting number of monocytes or CD34(+) cells (p = .016). Together, these data demonstrate that differences do exist between monocyte-derived DCs and CD34-derived DCs from the same cellular product (apheresis) from the same individual.     

脐血CD34+造血干/祖细胞基因表达图谱的研究

目的：通过脐血CD34^＋造血干／祖细胞的基因表达分析，理解造血干／祖细胞生物学特性。方法：利用MiniMACS免疫磁珠法从脐血细胞中分离CD34^＋造血干／祖细胞，提取总RNA，用SMART-PCR技术从微量RNA中扩增产生足够量的cDNA用于高密度点阵膜分析检测CD34^＋造血干／祖细胞表达的基因。结果：在所检测的588个基因中，发现63个基因具有显著的表达水平，其中18个基因强表达。这些基因主要涉及造血干细胞增殖、分化、应激响应、凋亡、转录调节以及细胞周期等。结论：对理解脐血干／祖细胞生物学性质以及指导造血干细胞体外培养提供了分子生物学基础。     

PGE_2促进人脐血CD34~+造血祖细胞向淋巴样树突状细胞分化

为了探讨前列腺素E2(protaglandin E2,PGE2)对人外周血CD14+单核细胞和脐血CD34+造血祖细胞(hematopoieticprogenitor cells,HPC)体外诱导pDC分化的影响。分别采用IL-4+GM-CSF+TNF-α和SCF+Flt-3L+GM-CSF+TNF-α诱导人外周血CD14+单核细胞和CD34+HPC向pDC分化,采用流式细胞仪分析细胞表型,并观察PGE2加入培养体系后对pDC分化的影响。结果:以CD34+HPC为来源,比CD14+单核细胞能诱导出更多数量且具有功能的pDC。培养体系中加入PGE2显著增强了CD34+HPC向pDC的分化,而对CD14+单核细胞的分化却无明显促进作用。PGE2可有效促进脐血CD34+HPC在多种细胞因子的作用下向pDC的成熟分化。     

Expansion of cytotoxic CD3+ CD56+ cells from peripheral blood progenitor cells of patients undergoing autologous hematopoietic cell transplantation.

Immunotherapy may potentially improve the outcome of autologous hematopoietic cell transplantation (HCT). Poor effector cell proliferation and marginal antitumor activity limit attempts to use immunotherapy. We have characterized the ex vivo expansion, up to 1000-fold, of CD3+ CD56+ lymphocytes from the peripheral blood lymphocytes (PBL) of healthy donors. Expanded cells termed cytokine-induced killer (CIK) cells induce non-major histocompatibility complex-restricted lysis of tumor cells and demonstrate cytolytic activity superior to lymphokine-activated killer cells without the requirement of interleukin (IL)-2 treatment in vivo. To determine whether cytolytic cells could be expanded from patient material, we evaluated samples of peripheral blood progenitor cells (PBPCs) from 25 patients undergoing autologous HCT. The PBPCs were expanded by priming with interferon-gamma followed by anti-CD3 monoclonal antibody and IL-2 the next day. Fluorescence-activated cell sorting analysis was performed on days 0, 15, 21, and 28 of cell culture. The median T-cell content rose from 15.3% (range, 1.1% to 89.7%) on day 0 to 97.2% (range, 83.6% to 99.5%) by day 15. By day 21, T cells expanded 21.8-fold (range, 1.7- to 420.0-fold) and CD3+ CD56+ cells expanded 44.8-fold (range, 5.1- to 747.0-fold). CIK cells were used as effector cells against B-cell lymphoma targets (OCI-Ly8) with a median of 24% (range, 3% to 67%) and 42% (range, 6% to 96%) specific lysis of target cells on days 21 and 28, respectively. CIK cells derived from PBL of 2 additional patients with acute myelogenous leukemia demonstrated 39% and 78% specific lysis of OCI-Ly8 and 26% and 58% specific lysis of autologous leukemic blasts at an effector:target ratio of 40:1. CIK cells may be expanded from granulocyte colony-stimulating factor-mobilized PBPCs of patients undergoing autologous HCT. CIK cells may provide a potent tool for use in posttransplantation adoptive immunotherapy.     

Engraftment of primates with G-CSF mobilized peripheral blood CD34+ progenitor cells expanded in G-CSF, SCF and MGDF decreases the duration and severity of neutropenia.

We used a primate model of autologous peripheral blood progenitor cell (PBPC) transplantation to study the effect of in vitro expansion on committed progenitor cell engraftment and marrow recovery after transplantation. Four groups of baboons were transplanted with enriched autologous CD34+ PBPC collected by apheresis after five days of G-CSF administration (100 microg/kg/day). Groups I and III were transplanted with cryopreserved CD34+ PBPC and Groups II and IV were transplanted with CD34+ PBPC that had been cultured for 10 days in Amgen-defined (serum free) medium and stimulated with G-CSF, megakaryocyte growth and development factor (MGDF), and stem cell factor each at 100 etag/ml. Group III and IV animals were administered G-CSF (100 microg/kg/day) and MGDF (25 microg/kg/day) after transplant, while animals in Groups I and II were not. For the cultured CD34+ PBPC from groups II and IV, the total cell numbers expanded 14.4 +/- 8.3 and 4.0 +/- 0.7-fold, respectively, and CFU-GM expanded 7.2 +/- 0.3 and 8.0 +/- 0.4-fold, respectively. All animals engrafted. If no growth factor support was given after transplant (Groups II and I), the recovery of WBC and platelet production after transplant was prolonged if cells had been cultured prior to transplant (Group II). Administration of post-transplant G-CSF and MGDF shortened the period of neutropenia (ANC < 500/microL) from 13 +/- 4 (Group I) to 10 +/- 4 (Group III) days for animals transplanted with non-expanded CD34+ PBPC. For animals transplanted with ex vivo-expanded CD34+ PBPC, post-transplant administration of G-CSF and MGDF shortened the duration of neutropenia from 14 +/- 2 (Group II) to 3 +/- 4 (Group IV) days. Recovery of platelet production was slower in all animals transplanted with expanded CD34+ PBPC regardless of post-transplant growth factor administration. Progenitor cells generated in vitro can contribute to early engraftment and mitigate neutropenia when growth factor support is administered post-transplant. Thrombocytopenia was not decreased despite evidence of expansion of megakaryocytes in cultured CD34+ populations.     

脐血CD34+CD19-造血干/祖细胞体外B细胞分化条件研究

目的:研究体外脐血造血干/祖细胞向B细胞分化的条件.方法:体外免疫磁珠分离纯化脐血CD34+CD19-造血干/祖细胞;在小鼠S-17基质细胞支持下,脐血CD34+CD19-造血干/祖细胞、T3、各种细胞因子共培养建立体外B细胞分化发育培养体系,诱导脐血CD34+CD19-造血干/祖细胞向B细胞分化;用流式细胞仪检测培养的B细胞.结果:T3、IL-7与小鼠S-17基质细胞共培养诱导CD34+CD19-造血干/祖细胞28天时,分化形成的B细胞数可达初始培养细胞的198倍,诱导细胞大部分表达CD10、CD19.结论:在选用的实验条件下,T3、IL-7与小鼠S-17基质细胞体外能诱导脐血造血干/祖细胞的B细胞分化.     

Clinical applications of CD34(+) peripheral blood progenitor cells (PBPC)

Recently, a number of devices have been developed for the positive selection of CD34(+) peripheral blood progenitor cells (PBPC) for clinical use in autologous or allogeneic transplantation. The rationale for CD34(+) selection is based on clinical studies showing a two- to five-log reduction of contaminating tumor cells in patients with breast cancer, multiple myeloma and low-grade lymphoma. In addition, a three- to five-log reduction of T cells can be obtained by CD34(+) selection in both autologous grafts for patients with autoimmune disease resistant to conventional therapy and allogeneic grafts to reduce the incidence and severity of acute graft-versus-host disease. Transplantation of positively selected autologous CD34(+) PBPC results in a rapid and stable neutrophil and platelet engraftment in patients who received an infused dose of at least 2.0 x 10(6) CD34(+) cells/kg. Results from randomized trials suggest that time to engraftment is not different compared to unmanipulated PBPC autografts. However, close monitoring for infectious complications (e.g., cytomegalovirus disease) is required. Allogeneic CD34(+) PBPC have also been successfully transplanted and, using novel technologies, megadoses of purified CD34(+) PBPC can be obtained and used to overcome histocompatibility differences betweeen allogeneic donor and patient resulting in stable engraftment, even in a haploidentical setting. Additional randomized phase III trials are required to determine whether tumor cell purging or lymphocyte depletion by CD34(+) cell selection will have a significant impact on progression-free and overall survival in both autologous and allogeneic transplantation.     

Intracellular localization and constitutive endocytosis of CXCR4 in human CD34+ hematopoietic progenitor cells

CXCR4, the stromal cell-derived factor-1 receptor, plays an important role in the migration of hematopoietic progenitor/stem cells. The surface and cytoplasmic expression of CXCR4 on human hematopoietic CD34(+) cells was investigated. We show that its surface expression is low, whereas a large part of CXCR4 protein is sequestered intracellularly. Using confocal microscopy, we demonstrated that CXCR4 is colocalized with EEA-1, Rab5, Rab4, and Rab11, which are localized in early and recycling endosomes. No significant colocalization of CXCR4 with lysosomal markers CD63 and Lamp-1 was detected. Using antibody feeding experiments, we report a role for CXCR4 constitutive endocytosis in subcellular localization in stably transduced UT7-CXCR4-GFP and CD34(+) cells. Agonist-independent endocytosis of CXCR4 occurs through clathrin-coated vesicles. These data implicate a constitutive endocytosis in the regulation of CXCR4 membrane expression and suggest that constitutive endocytosis may be involved in the regulation of trafficking the human hematopoietic progenitor/stem cells to and in the bone marrow microenvironment.