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Although the efficacy of plerixafor in peripheral blood stem cell (PBSC) mobilization has been explored in several studies, factors associated with successful plerixafor mobilization after administration of granulocyte-colony-stimulating factor (G-CSF), with or without chemotherapy, have not been investigated. We analyzed data on PBSC mobilization from a large Italian database of lymphoma and myeloma plerixafor-treated patients.Two endpoints were established to define successful mobilization: patients with at least 2 × 10(6) CD34+ cells/kg collected by three leukapheresis procedures and patients achieving a peak count of at least 20 × 10(6) CD34+ cells/L during mobilization.Plerixafor achieved successful mobilization in both predicted (n = 64) and proven poor mobilizers (PMs; n = 143), classified according to the Gruppo Italiano Trapianto di Midollo Osseo (GITMO) criteria. Successful mobilization was independent of type of mobilization (steady state or chemotherapy); age; sex; disease; number or type of chemotherapy regimens preceding plerixafor; radiation therapy; prior treatment with melphalan, carmustine, lenalidomide, and radioimmune conjugates; and laboratory variables. Multivariate analysis identified previous fludarabine treatment and premobilization platelet count as predictors of successful mobilization.This large, prospective, nationwide study confirmed plerixafor efficacy for mobilizing PBSCs when added to G-CSF with or without chemotherapy. Plerixafor can overcome negative effects of most predictors of poor mobilization to achieve satisfactory harvest both in predicted and proven PM.

Cell therapy can be considered as a strategy aimed at replacing, repairing, or enhancing the biological function of a damaged tissue or system by means of autologous or allogeneic cells. There have been major advances in this field in the last few years. This has prompted the Working Group on Hematopoietic Cells to examine the current utilization of this therapy in clinical hematology.The method employed for preparing this review was that of informal consensus development. Members of the Working Group met three times, and the participants at these meetings examined a list of problems previously prepared by the chairman. They discussed the single points in order to reach an agreement on different opinions and eventually approved the final manuscript. Some of the authors of the present review have been working in the field of cell therapy and have contributed original papers in peer-reviewed journals. In addition, the material examined in the present review includes articles and abstracts published in journals covered by the Science Citation Index and Medline.Lymphokine-activated killer (LAK) and tumor-infiltrating lymphocytes (TIL) have been used since the '70s mainly in end-stage patients with solid tumors, but the clinical benefits of these treatments has not been clearly documented. TIL are more specific and potent cytotoxic effectors than LAK, but only in few patients (mainly in those with solid tumors such as melanoma and glioblastoma) can their clinical use be considered potentially useful. Adoptive immunotherapy with donor lymphocyte infusions has proved to be effective, particularly in patients with chronic myeloid leukemia, in restoring a state of hematologic remission after leukemia relapse occurring following an allograft. The infusion of donor T-cells can also have a role in the treatment of patients with Epstein-Barr virus (EBV)-induced post-transplant lymphoproliferative disorders. However, in this regard, generation and infusion of donor-derived, virus specific T-cell lines or clones represents a more sophisticated and safer approach for treatment of viral complications occurring in immunocompromised patients. Whereas too few clinical trials have been performed so far to draw any firm conclusion, based on animal studies dendritic cell-based immunotherapy holds promises of exerting an effective anti-tumor activity. Despite leukemic cells not being immunogenic, induction on their surface of co-stimulatory molecules or generation of leukemic dendritic cells may induce antileukemic cytotoxic T-cell responses. Tumor cells express a variety of antigens and can be genetically manipulated to become immunogenic. The main in vitro and in vivo functional characteristics of marrow mesenchymal stem cells (MSCs) with particular emphasis on their hematopoietic regulatory role are reviewed. In addition, prerequisites for clinical applications using culture-expanded mesenchymal cells are discussedThe opportuneness of using LAK cells or activated natural killer (NK) cells in hematologic patients with low tumor burden (e.g. after stem cell transplantation) should be further explored. Moreover the role of new cytokines in enhancing the antineoplastic activity of NK cells and the infusion of selected NK in alternative to CTL for graft versus leukemia (GVL) disease (avoiding graft versus host disease (GvHD) seems very promising. Separation of GVL from GvHD through generation and infusion of leukemia-specific T-cell clones or lines is one of the most intriguing and promising fields of investigations for the future. Likewise, strategies devised to improve immune-reconstitution and restore specific anti-infectious functions through either induction of unresponsiveness to recipient alloantigens or removal of alloreactive donor T-cells might increase the applicability and success of hematopoietic stem cell transplantation. (ABSTRACT TRUNCATED)

Idiopathic thrombocytopenic purpura (ITP) induces thrombocytopenia by means of an autoimmune mechanism. Despite the available therapies a subset of patients develop chronic refractory severe thrombocytopenia (i.e. a platelet count consistently lower than 20 to 30x10(9)/L), and life-threatening bleeding can occasionally occur. It has been suggested that the risk of major bleeding is higher in elderly patients and in patients with bleeding at diagnosis. However, since clear data on the influence of clinical and/or laboratory parameters on outcome are lacking, some patients may be receiving unnecessary treatment.We made a retrospective analysis of a series of 310 patients with chronic ITP (108 males and 202 females), with a median age at diagnosis of 40 years (range 8-87 years). The median follow-up time was 121 months, (range 7-434 months). Therapy was most often started in the presence of hemorrhagic complications and/or a platelet count30x10(9)/L either at diagnosis or during follow-up.Our findings confirmed that patients who were symptomatic at diagnosis were more likely to have bleeding during their follow-up. Moreover, all the patients who suffered major bleeding during their follow-up had median platelet counts of 10x10(9)/L (range 1-20) at that time. Only one patient, aged 43 years, died of hemorrhage following prolonged severe thrombocytopenia. Age60 years was not associated with any significant differences in incidence of bleeding at diagnosis or during follow-up.We conclude that prospective studies are required to evaluate whether it may be reasonable to treat only symptomatic patients, independently of age.

We review here the functional and kinetic characteristics of highly purified hematopoietic CD34+ mobilized into peripheral blood (PB) by granulocyte colony-stimulating factor (G-CSF) with or without chemotherapy for autologous or allogeneic transplantation. Circulating CD34+ cells were evaluated for their colony-forming capacity and trilineage proliferative response to selected recombinant human (rh) CSF in vitro, and the content of very primitive long-term culture initiating cells (LTC-IC). In addition, the cycling status of PB CD34+ cells, including committed clonogenic progenitor cells and the more immature LTC-IC, was determined by the cytosine arabinoside (Ara-C) suicide test and the acridine orange (AO) flow cytometric technique. By comparison, bone marrow (BM) CD34+ cells from the same individuals were studied under steady-state conditions and during G-CSF administration. Clonogenic assays in methylcellulose showed the same frequency of colony-forming unit cells (CFU-C) when PB primed-CD34+ cells and BM cells were stimulated with phytohemagglutinin-lymphocyte-conditioned medium (PHA-LCM). However, mobilized CD34+ cells were significantly more responsive than their steady-state BM counterparts to interleukin-3 (IL-3) and stem cell factor (SCF) combined with G-CSF or IL-3 in the presence of erythropoietin (Epo). Conversely, circulating and BM megakaryocyte precursors (CFU-MK) showed the same clonogenic efficiency in response to IL-3, GM-CSF and IL-3, IL-6 and Epo. Interestingly, very few CD34+ cells expressed the Mpl receptor and this finding resulted in the lower proliferative response of mobilized CFU-MK to the Mpl-ligand (megakaryocyte growth and development factor; MGDF), as compared to BM cells. After 5 weeks of liquid culture supported by the engineered murine stromal cell line M2-10B4 to produce G-CSF and IL-3, we reported a similar frequency of LTC-IC in PB and steady-state BM. Kinetic studies on PB and BM CD34+ cells, including LTC-IC, showed the low number of circulating progenitor cells in S and G2M phase whereas simultaneous DNA/RNA analysis and the Ara-C suicide assay demonstrated that the majority of PB CD34+ cells and LTC-IC are not quiescent (ie in G0 phase) being in G1 phase. Moreover, G-CSF administration prevented apoptosis in a small but significant proportion of mobilized CD34+ cells. Thus, our results indicate that mobilized and BM CD34+ cells can be considered equivalent for the frequency of both committed and more immature hematopoietic progenitor cells, although they show different kinetic and functional profiles. A further set of experiments indicated that G-CSF treatment did not alter the alloantigen presenting function of CD34+ cells which was mainly mediated by the upregulation of costimulatory molecules upon coincubation with allogeneic T cells. Taken together, these findings should allow a better understanding of PBSC transplantation.

Hematopoietic stem cells are being increasingly used for treatment of malignant and nonmalignant disorders. Various attempts have been made in recent years to expand and manipulate these cells in order to increase their therapeutic potential. A Working Group on Hematopoietic Cells has analyzed the most recent advances in this field.The method used for preparing this review was an informal consensus development. Members of the Working Group met three times, and the participants at these meetings examined a list of problems previously prepared by the chairman. They discussed the single points in order to achieve an agreement on different judgments, and eventually approved the final manuscript. Some authors of the present review have been working in the field of stem cell biology, processing and transplantation, and have contributed original papers in peer-reviewed Journals. In addition, the material examined in the present review includes articles and abstracts published in Journals covered by the Science Citation Index and Medline.Over the last decade, recombinant DNA technology has allowed the large scale production of cytokines controlling the proliferation and differentiation of hemo-lymphopoietic cells. Thus, in principle, ex vivo manipulation of hemopoiesis has become feasible. The present review covers three major area of interest in experimental and clinical hematology: manipulation of hematopoietic stem/progenitor cells, cytotoxic effector cells and antigen presenting dendritic cells. Preliminary data demonstrate the possibility of using, in a clinical setting, ex vivo expanded hematopoietic cells with the aim of reducting, and perhaps abrogating, the myelosuppression after high-dose chemotherapy. Concurrently, other important potential applications for ex vivo manipulation of hematopoietic cells have recently been investigated such as the generation and expansion of cytotoxic cells for cancer immunotherapy, and the large scale production of professional antigen presenting cells capable of initiating the process of immune response.Present and future challenges in this field are represented by the expansion of true human stem cells without maturation, to extend this strategy to allogeneic stem cell transplantation as well as the manipulation of cycling of primitive progenitors for gene therapy programs. The selective outgrowth of normal progenitor cells over neoplastic cells to achieve tumor-free autografts may ameliorate the results of autologous transplantation. The selective production of cellular subsets to manipulate the graft versus-host and graft versus-tumor effects and anti-tumor vaccination strategies may be important to improve cellular adoptive immunotherapy.

Identification and characterization of hematopoietic stem cells in peripheral blood (PB) and cord blood (CB) have suggested feasible alternatives to conventional allogeneic bone marrow (BM) transplantation. The growing interest in this use of allogeneic stem cells has prompted the Working Group on CD34-positive Hematopoietic Cells to review this subject by analyzing its biological and technical aspects.The method used for preparing this review was informal consensus development. Members of the Working Group met three times, and the participants at these meetings examined a list of problems previously prepared by the chairman. They discussed the individual points in order to reach an agreement on the various concepts, and eventually approved the final manuscript. Some of the authors of the present review have been working in the field of hematopoietic stem cell biology and processing, and have contributed original papers published in peer-reviewed journals. In addition, the material examined in the present review includes articles and abstracts published in journals covered by the Science Citation Index and Medline.Several studies have now shown that hematopoietic stem cells collected from peripheral blood after the administration of G-CSF, or from cord blood upon delivery, are capable of supporting rapid and complete reconstitution of BM function in allogeneic recipients. Perhaps more importantly, reinfusion of large numbers of HLA-matched T-cells from PB collections or T-cells with various degrees of HLA disparity from CB did not result in a higher incidence or greater severity of acute graft-versus-host disease than expected with BM. Based on the data reviewed, operative guidelines for mobilization, collection and graft processing are provided.It should be remembered that despite the growing interest, these procedures must be still considered as advanced clinical research and should be included in formal clinical trials aimed at demonstrating their definitive role in stem cell transplantation. In this regard, a large European randomized study is currently comparing PB and BM allografts. However, the possibility of collecting large quantities of hematopoietic progenitor-stem cells, perhaps with reduced allo-reactivity, offers an exciting perspective for widening the number of potential stem cell donors and greater leeway for graft manipulation than is possible with BM.

We have recently reported that the hematologic recovery of patients with non-Hodgkin's lymphoma (NHL) and Hodgkin's disease (HD) undergoing autologous bone marrow transplantation (BMT) is significantly faster when recombinant human interleukin-3 (rhIL-3) is combined with recombinant human granulocyte colony-stimulating factor (rhG-CSF) in comparison with patients receiving G-CSF alone. In this paper, we studied the kinetic response and concentration of BM progenitor cells of 17 patients with lymphoid malignancies submitted to autologous BMT and treated with the G-CSF/IL-3 combination. The results were compared with those of five lymphoma patients receiving the same pretransplant conditioning regimen followed by G-CSF alone. rhG-CSF was administered as a single subcutaneous (sc) injection at the dose of 5 micrograms/kg/d from day 1 after reinfusion of autologous stem cells; rhIL-3 was added from day 6 at the dose of 10 micrograms/kg/d sc (overlapping schedule). In both groups (G-CSF- and G-CSF/IL-3-treated patients), cytokine administration was discontinued when the absolute neutrophil count (ANC) was0.5 x 10(9)/L of peripheral blood (PB) for 3 consecutive days. After treatment with the CSF combination, the percentage of marrow colony-forming units-granulocyte/macrophage (CFU-GM) and erythroid progenitors (BFU-E) in S phase of the cell cycle increased from 9.3 +/- 2% to 33.3 +/- 12% and from 14.6 +/- 3% to 35 +/- 6%, respectively (p0.05). Similarly, we observed an increased number of actively cycling megakaryocyte progenitors (CFU-MK and BFU-MK). Conversely, G-CSF augmented the proliferative rate of CFU-GM (22.6 +/- 0.6% compared to a baseline value of 11.5 +/- 3%; p0.05) but not of BFU-E, CFU-MK, or BFU-MK, and the increase of S-phase CFU-GM was significantly lower than that observed in the posttreatment samples of patients receiving IL-3 in addition to G-CSF. The frequency of hematopoietic precursors in the BM, expressed as the number of colonies formed per number of cells plated, was unchanged or slightly decreased in both groups of patients. Because of the increase in marrow cellularity, however, a significant augmentation of the absolute number of both CFU-GM (3605 +/- 712/mL BM vs. 2213 +/- 580/mL; p0.05) and BFU-E (4373 +/- 608/mL vs. 3027 +/- 516/mL; p0.05) was reported after treatment with G-CSF/IL-3 but not G-CSF alone. Similarly, administration of the cytokine combination resulted in a higher number of CD34+ cells/mL BM, and their concentration was significantly greater than that observed in the posttreatment samples of G-CSF patients. Finally, we investigated the responsiveness to CSFs, in vitro, of highly enriched CD34+ cells, collected after priming with G-CSF in vivo (i.e., after 5 days of G-CSF administration). Our results demonstrated that pretreatment with G-CSF modified the response of BM cells to subsequent stimulation with additional CSFs. The results presented in this paper indicate that in vivo administration of two cytokines increases the proliferative rate and concentration of BM progenitor cells to a greater degree than G-CSF alone. These results support the role of growth factor combinations for accelerating hematopoietic recovery after high-dose chemotherapy.

Human CD34+ hematopoietic cells were purified using the avidin-biotin immunoabsorption technique. The selected population showed 78.6 +/- 3% CD34+ cells and the overall recovery of CD34+ cells, CFU-GM and BFU-E from the starting population was 34 +/- 5%, 71 +/- 4% and 67 +/- 2%, respectively. Hematopoietic progenitor cell purification also resulted in 3 log of normal T cell depletion from the bone marrow (BM) by immunofluorescence analysis. Moreover, when unseparated BM cells were mixed with the CD34- lymphoma cell lines D430B and Raji, the removal of greater than 3 log of tumor cells from the enriched CD34+ cell fraction was demonstrated. To increase the neoplastic cell purging, several immunotoxins (IT) containing the ribosome-inactivating protein (RIP) saporin and directed toward the lymphoid-associated antigens CD30 and CD2 were prepared. Our experiments showed only a minimal toxicity of the immunoconjugates on colony-forming cells (CFC) derived from purified CD34+ cells. Conversely, all the ITs were very effective in inhibiting protein synthesis and growth of normal and neoplastic lymphoid cells. Further experiments demonstrated that the sequential combination of CD34+ cells purification and IT treatment resulted in 5 or more log of tumor cell purging with no additional loss of BM progenitor cells.

Laboratory studies have suggested that hematopoietic growth factors (GF), combined with cytosine-arabinoside (Ara-C) can enhance cytotoxic effects of this agent against acute myeloid leukemia (AML) cells. While clinical trials based on this growth factor/chemotherapy combination (GF/CT) are progressing with discordant results, further information regarding the underlying mechanisms have been reported supporting this rationale and requiring additional investigation. To assess the role of cytokinetic changes in the GF/CT strategy and to evaluate if chemotherapeutic agents regimens other than Ara-C, when combined with GF, can enhance their cytotoxic effects, we have primed AML blasts with two cytokine combinations and then exposed these cells to the S-phase specific agent Ara-C as well as to the phase non-specific drug daunorubicin (DNR) and to the alkylating agent 4-hydroperoxycyclophosphamide (4-HC). The two cytokine combinations used for priming AML blasts were: (i) interleukin-3 (IL-3) + granulocyte-macrophage colony-stimulating factor (GM-CSF) + granulocyte colony-stimulating factor (G-CSF); and (ii) GM + G-CSF. Cytokinetic analysis in ten AML samples and clonogenic growth of leukemic colonies (CFU-L) in methylcellulose were used to detect proliferative and cytotoxic effects on AML samples. We report that in AML clonogenic cell growth can be stimulated by cytokines in 50% of the samples (4/8), and that Ara-C sensitization clearly occurs in two out of these four samples. Among the different cytokine combinations tested, the one containing IL-3 was the most effective through a cytokinetic mechanism consistent with recruitment (averaged G0 decrease p = 0.04; S-phase increase p = 0.005). Furthermore we observed increased cytotoxicity also to the phase non-specific drugs DNR and 4-HC, which may be mediated by other mechanisms recently described. We conclude that GF/CT combinations may also be beneficial in regimens containing drugs other than Ara-C, used for AML treatment, including bone marrow transplantation conditioning regimens.