Red blood cell concentrates treated with the amustaline (S-303) pathogen reduction system and stored for 35 days retain post-transfusion viability: results of a two-centre study.

BACKGROUND AND OBJECTIVES: Pathogen reduction technology using amustaline (S-303) was developed to reduce the risk of transfusion-transmitted infection and adverse effects of residual leucocytes. In this study, the viability of red blood cells (RBCs) prepared with a second-generation process and stored for 35 days was evaluated in two different blood centres. MATERIALS AND METHODS: In a single-blind, randomized, controlled, two-period crossover study (n = 42 healthy subjects), amustaline-treated (Test) or Control RBCs were prepared in random sequence and stored for 35 days. On day 35, an aliquot of 51 Cr/99m Tc radiolabeled RBCs was transfused. In a subgroup of 26 evaluable subjects, 24-h RBC post-transfusion recovery, mean life span, median life span (T50 ) and life span area under the curve (AUC) were analysed. RESULTS: The mean 24-h post-transfusion recovery of Test and Control RBCs was comparable (83·2 ± 5·2 and 84·9 ± 5·9%, respectively; P = 0·06) and consistent with the US Food and Drug Administration (FDA) criteria for acceptable RBC viability. There were differences in the T50 between Test and Control RBCs (33·5 and 39·7 days, respectively; P < 0·001), however, these were within published reference ranges of 28-35 days. The AUC (per cent surviving × days) for Test and Control RBCs was similar (22·6 and 23·1 per cent surviving cells × days, respectively; P > 0·05). Following infusion of Test RBCs, there were no clinically relevant abnormal laboratory values or adverse events. CONCLUSION: RBCs prepared using amustaline pathogen reduction meet the FDA criteria for post-transfusion recovery and are metabolically and physiologically appropriate for transfusion following 35 days of storage.

Nuclear Vav3 is required for polycomb repression complex-1 activity in B-cell lymphoblastic leukemogenesis.

Acute B-cell lymphoblastic leukemia (B-ALL) results from oligo-clonal evolution of B-cell progenitors endowed with initiating and propagating leukemia properties. The activation of both the Rac guanine nucleotide exchange factor (Rac GEF) Vav3 and Rac GTPases is required for leukemogenesis mediated by the oncogenic fusion protein BCR-ABL. Vav3 expression becomes predominantly nuclear upon expression of BCR-ABL signature. In the nucleus, Vav3 interacts with BCR-ABL, Rac, and the polycomb repression complex (PRC) proteins Bmi1, Ring1b and Ezh2. The GEF activity of Vav3 is required for the proliferation, Bmi1-dependent B-cell progenitor self-renewal, nuclear Rac activation, protein interaction with Bmi1, mono-ubiquitination of H2A(K119) (H2AK119Ub) and repression of PRC-1 (PRC1) downstream target loci, of leukemic B-cell progenitors. Vav3 deficiency results in de-repression of negative regulators of cell proliferation and repression of oncogenic transcriptional factors. Mechanistically, we show that Vav3 prevents the Phlpp2-sensitive and Akt (S473)-dependent phosphorylation of Bmi1 on the regulatory residue S314 that, in turn, promotes the transcriptional factor reprogramming of leukemic B-cell progenitors. These results highlight the importance of non-canonical nuclear Rho GTPase signaling in leukemogenesis.

On how Rac controls hematopoietic stem cell activity.

Rac GTPases form part of the family of Rho small GTPases. Rac GTPases, like other Rho family GTPases, are key molecular switches controlling the transduction of external signals to cytoplasmic and nuclear effectors. The development of genetic and pharmacological tools has allowed a more precise definition of the specific roles of Rac GTPases in hematopoietic stem cells (HSCs). Our current knowledge has enabled dissection of their specific and redundant roles. Rac GTPases are now known to be crucial in the response of HSCs to the hematopoietic microenvironment cues. This review will briefly summarize the known HSC functions that are regulated by Rac GTPases, focusing on adhesion, migration, retention, proliferation, and survival, and how Rac relates to the physiological functions of HSC. The development of small molecule inhibitors with the ability to interfere with Rac GTPase activation offers new therapeutic strategies to manipulate the function of HSC in vivo and ex vivo.

Coagulation factor content of plasma produced from whole blood stored for 24 hours at ambient temperature: results from an international multicenter BEST Collaborative study.

BACKGROUND: There is increasing international interest in producing components from blood that has been stored at room temperature for 24 hours. The lack of comprehensive data on the quality of plasma produced from blood stored in this way led to this international study. STUDY DESIGN AND METHODS: A total of 128 units of whole blood were pooled in groups of four and split to produce 32 sets of four identical blood units that were processed either within 8 hours of blood collection or after 24-hour storage at 18 to 25°C. RESULTS: Storage of whole blood for 24 hours resulted in a 23% decrease in the activity of Factor (F)VIII, but not significant loss of activity of coagulation factors FV, FVII, FXI, FXII, fibrinogen, antithrombin, or von Willebrand factor. There was a small, but significant decrease in levels of FII, FIX, and FX (all <5%) as well as protein C (6%) and free protein S activity (14%). The ability of plasma to generate thrombin after 24-hour storage as whole blood was unaltered, as assessed by real-time thrombin generation tests as was the rate and strength of clot formation by rotational thombelastometry. Levels of all coagulation factors measured were above 0.50 U/mL in plasma produced from whole blood stored for 24 hours. CONCLUSION: These data show that there is minimal effect of storing whole blood at ambient temperature for 24 hours on the coagulation activity of plasma and that this is an acceptable alternative to producing plasma on the day of blood collection.

Multi-institutional randomized control study of haemolysis in stored red cell units prepared manually or by an automated system.

BACKGROUND: The haemolysis level at the end of storage is a performance parameter for RBC preparations. In the evaluation of new devices or new processes for processing blood, it is relevant to evaluate whether the haemolysis is linked to (1) specific characteristics of the blood donor, or (2) the nature of the blood-processing methodologies. MATERIALS AND METHODS: As part of the validation of a new automated whole blood processing system compared to the current manual methods, randomized, paired crossover studies were conducted evaluating measures of blood component quality, including RBC haemolysis over 42 days of storage. RESULTS: The association between haemolysis and the individual subject was evaluated by modelling haemolysis with independent predictors of treatment (control and test processing) and leucocyte reduction as fixed factors with donor and laboratory as random effects in a mixed-effects ANOVA model. It was found that the day 42 haemolysis values were strongly dependent on the donor subject, with an intraclass correlation coefficient of 0.81. CONCLUSIONS: The data reported in this study suggest a link between the specific whole blood donor and the haemolysis levels observed in red-blood-cell units stored refrigerated for 42 days. Additional research to identify possible donor characteristics associated with haemolysis during storage is warranted.

The signaling axis atypical protein kinase C λ/ι-Satb2 mediates leukemic transformation of B-cell progenitors.

Epigenetically regulated transcriptional plasticity has been proposed as a mechanism of differentiation arrest and resistance to therapy. BCR-ABL leukemias result from leukemic stem cell/progenitor transformation and represent an opportunity to identify epigenetic progress contributing to lineage leukemogenesis. Primary human and murine BCR-ABL+ leukemic progenitors have increased activation of Cdc42 and the downstream atypical protein kinase C (aPKC). While the isoform aPKCζ behaves as a leukemic suppressor, aPKCλ/ι is critically required for oncogenic progenitor proliferation, survival, and B-cell differentiation arrest, but not for normal B-cell lineage differentiation. In vitro and in vivo B-cell transformation by BCR-ABL requires the downregulation of key genes in the B-cell differentiation program through an aPKC λ/ι-Erk dependent Etv5/Satb2 chromatin repressive signaling complex. Genetic or pharmacological targeting of aPKC impairs human oncogenic addicted leukemias. Therefore, the aPKCλ/ι-SATB2 signaling cascade is required for leukemic BCR-ABL+ B-cell progenitor transformation and is amenable to non-tyrosine kinase inhibition.

Genetic and pharmacologic evidence that Rac1 GTPase is involved in regulation of platelet secretion and aggregation.

BACKGROUND: Rac1 GTPase, a member of the Ras-related Rho GTPase family, is the major Rac isoform present in platelets and has been shown to be involved in cell actin cytoskeleton reorganization and adhesion. Agonists that induce platelet secretion and aggregation also activate Rac1 GTPase, raising the possibility that Rac1 GTPase may be involved in regulation of platelet function. OBJECTIVES: To rigorously define the role of Rac1 in platelet regulation. METHODS: We have used a dual approach of gene targeting in mice and pharmacologic inhibition of Rac1 by NSC23766, a rationally designed specific small molecule inhibitor, to study the role of Rac1 in platelet function. RESULTS: Platelets from mice as well as human platelets treated with NSC23766 exhibited a significant decrease in: (i) active Rac1 species and phosphorylation of the Rac effector, p21-activated kinase; (ii) expression of P-selectin and secretion of adenosine triphosphate induced by thrombin or U46619; and (iii) aggregation induced by adenosine 5'-diphosphate, collagen, thrombin and U46619, a stable analog of thromboxane A(2). NSC23766 did not alter the cAMP or cGMP levels in platelets. Consistent with the requirement of Rac1 for normal platelet function, the bleeding times in Rac1(-/-) mice or mice given NSC23766 were significantly prolonged. CONCLUSIONS: Our data show that deficiency or inhibition of Rac1 GTPase blocks platelet secretion. The inhibition of secretion, at least in part, is responsible for diminished platelet aggregation and prolonged bleeding times observed in Rac1 knockout or Rac1 inhibitor-treated mice.

Enhanced expression of alpha(1,3)-fucosyltransferase genes correlates with E-selectin-mediated adhesion and metastatic potential of human lung adenocarcinoma cells.

Alpha(1,3)- and alpha(1,4)-fucosylated oligosaccharides such as sialyl-Lewis(x) (sialyl-Le(x)) and sialyl-Lewis(a) (sialyl-Le(a)) have been reported to participate in tumor cell adhesion to activated endothelium. We examined by cytofluorometry the expression of Le(x), sialyl-Le(x), sialyl-Le(x) dimeric, Le(a), and sialyl-Le(a) on the surface of two human lung adenocarcinoma cell lines with different lung colonization potential. High expression levels of all of these antigens were detected in the metastatic HAL-8Luc cells, whereas the closely related nonmetastatic HAL-24Luc cells only expressed the sialyl-Le(a) and sialyl-Le(x) dimeric antigens, both at lower level than in HAL-8Luc cells. Five alpha(1,3)-fucosyltransferases (alpha(1,3)-Fuc-T) controlling the synthesis of these molecules have been identified to date (Fuc-TIII-Fuc-IVII). The expression of these five genes was also higher in the metastatic cells than in the nonmetastatic counterparts as was shown by Northern blot analysis. In vitro adhesion assays showed that only the metastatic cell line adheres significantly to E-selectin-expressing human endothelial cells. Moreover, monoclonal antibody (mAb) blockade of E-selectin completely abolished tumor cell binding. Adhesion inhibition experiments using mAbs against sialylated fucosylated oligosaccharides expressed on tumor cells indicated that these antigens are involved in the binding. Anti-sialyl-Lex(x) mAb (CSLEX-1) inhibited adhesion by 85%; it had the most pronounced inhibitory effect. These findings suggest that the overexpression of alpha(1,3)-Fuc-T genes in the metastatic HAL-8Luc cells, compared with HAL-24Luc cells, results in an enhanced surface display of fucosylated oligosaccharides, which contributes to the adhesive capacity of these cells to the activated endothelium and correlates with their lung colonization potential.

The DEK oncogene promotes cellular proliferation through paracrine Wnt signaling in Ron receptor-positive breast cancers.

Disease progression and recurrence are major barriers to survival for breast cancer patients. Understanding the etiology of recurrent or metastatic breast cancer and underlying mechanisms is critical for the development of new treatments and improved survival. Here, we report that two commonly overexpressed breast cancer oncogenes, Ron (Recepteur d'Origine Nantaise) and DEK, cooperate to promote advanced disease through multipronged effects on ß-catenin signaling. The Ron receptor is commonly activated in breast cancers, and Ron overexpression in human disease stimulates ß-catenin nuclear translocation and is an independent predictor of metastatic dissemination. Dek is a chromatin-associated oncogene whose expression has been linked to cancer through multiple mechanisms, including ß-catenin activity. We demonstrate here that Dek is a downstream target of Ron receptor activation in murine and human models. The absence of Dek in the MMTV-Ron mouse model led to a significant delay in tumor development, characterized by decreased cell proliferation, diminished metastasis and fewer cells expressing mammary cancer stem cell markers. Dek complementation of cell lines established from this model was sufficient to promote cellular growth and invasion. Mechanistically, Dek expression stimulated the production and secretion of Wnt ligands to sustain an autocrine/paracrine canonical ß-catenin signaling loop. Finally, we show that Dek overexpression promotes tumorigenic phenotypes in immortalized human mammary epithelial MCF10A cells and, in the context of Ron receptor activation, correlates with disease recurrence and metastasis in patients. Overall, our studies demonstrate that DEK overexpression, due in part to Ron receptor activation, drives breast cancer progression through the induction of Wnt/ß-catenin signaling.

Procoagulant activity of T lymphoblastoid cells due to exposure of negatively charged phospholipid.

We have characterised the Procoagulant activity (PCA) of six well-established cell lines by assays of tissue factor (TF), thrombin and FXa generation, flow cytometry using Annexin V, and by binding studies with Factors VIII and IXa. The monocytic (THP-1 & U937) and promyelocytic (NB4) cells expressed high concentrations of TF antigen and activity, whereas TF in the lymphocytic cells (Molt 4, Jurkat & Nalm 6) was very low or absent. However the T-lymphoblastoid cells (Molt 4 & Jurkat) promoted the generation of large amounts of thrombin despite their low TF content, and these cells were also the most active in supporting Factor Xa generation. Molt 4 cells bound Factors VIII and IXa with high capacity and their activity was inhibited by Annexin V. These results indicate that the PCA of T-lymphoblastoid lines is due to expression of negatively charged phospholipids. Flow cytometry studies showed Annexin V binding to the major population of nonapoptotic Molt 4 cells and the PCA of Molt 4 was not increased when apoptosis was induced by staurosporine, indicating that PCA is independent of apoptotic status.

Parathyroid hormone-related peptide stimulates DNA synthesis and insulin secretion in pancreatic islets.

Parathyroid hormone (PTH)-related protein (PTHrP) is present in the pancreatic islet. Recent data in transgenic mice suggest that PTHrP might modulate islet mass and insulin secretion. In the present study, we assessed the effect of the N-terminal PTH-like region of PTHrP on DNA synthesis in isolated rat islets. PTHrP (1-34), between 1 pM and 10 nM, for 48 h stimulated []thymidine incorporation into rat islets. This effect was maximally induced, about 2.5-fold over control, by 10 pM of this peptide, decreasing thereafter. In contrast, PTHrP (38-64) amide or PTHrP (107-139) were ineffective in increasing DNA synthesis in islets. Using reverse transcription followed by PCR, we confirmed that rat islets express PTHrP and the type I PTH/PTHrP receptor. Addition of a neutralizing anti-PTHrP antibody to the incubation medium of proliferating islets decreased islet DNA synthesis by 30%. The effect of a submaximal dose (30 pM) of PTHrP (1-34) on DNA synthesis in rat islets was abolished by 25 nM bisindolylmaleimide I, a protein kinase C (PKC) inhibitor, but not by 25 microM adenosine 3',5'-cyclic monophosphorothioate, Rp-isomer, a protein kinase A inhibitor. Moreover, 100 nM phorbol-12-myristate-13-acetate for 48 h also increased DNA synthesis 2-fold over controls in islets. PTHrP (1-34), at 100 nM, in contrast to 50 microM forskolin or 10 mM NaF, failed to affect adenylate cyclase activity in islet membranes. PTHrP, at 30 pM, was also found to increase 2-fold insulin released into the islet-conditioned medium within 24-48 h. Our results suggest that PTHrP is a modulator of pancreatic islet growth and/or function by a PKC-mediated mechanism.

Expansion of cord blood progenitor cells.

Cord blood (CB) provides an alternative source of stem cells for transplantation, although in a considerable number of cases CB transplantation is followed by long periods of aplasia. Ex vivo expansion has the capacity to generate large amounts of progenitors, and it has been proposed that expanded cells might be beneficial in overcoming these long periods of aplasia. We describe the biological characteristics of cord blood compared to other sources of stem cells (BM and PB), and report the effects of FLT3-L and MIP-1alpha when added to a combination of SCF, IL-3 and IL-6 in pre-clinical short-term, serum-free expansion cultures of CB-derived CD34+ cells. After 6 days, this culture system was able to generate considerable expansion rates in the committed compartment (between 8.16- and 17.26-fold for CFU-GM, and 21.58- and 36.53-fold for the BFU-E/CFU-Mix), and the CD34+ population (between 11.25- and 25.42-fold). Moreover, this culture system was also able to maintain the week 5 CAFC population, particularly when both FLT3-L and MIP-1alpha were present (91% of the input level). Thus, we have described a pre-clinical protocol for ex vivo expansion of CB CD34+ cells in a short-term, static, serum-free system, where a high generation of committed progenitor cells is achieved together with CAFC maintenance.

Efficient peripheral blood stem cell mobilization with low-dose G-CSF (50 microg/m2) after salvage chemotherapy for lymphoma.

We compared the use of low-dose G-CSF (50 microg/m2/day), following salvage chemotherapy, for mobilization of PBSC with the results obtained in a comparable historical control group who received a standard dose of G-CSF (5 microg/kg/day, approximately 200 microg/m2/day). Thirty adult patients with relapsed or refractory lymphoma were treated with ifosfamide, VP-16, intermediate-dose Ara-C, methylprednisolone (IAPVP-16) and G-CSF 5 microg/kg/day (group A, n = 15) or 50 microg/m2/day (group B, n = 15) from day 6 until the end of leukaphereses. The duration of neutropenia and thrombocytopenia were equal in both groups. A median of two (1-3) leukaphereses were performed in both groups to harvest >3.5 x 10(6)/kg CD34+ cells. The numbers of circulating CD34+ cells on the first day of leukocyte recovery were similar in both groups in those patients mobilized after a first cycle of IAPVP-16. The numbers of circulating CD34+ cells were similar in patients mobilized after a first and after a second IAPVP-16 in group A. In the low-dose group (group B), however, the numbers of circulating CD34+ cells were significantly lower in those mobilized after a second than after a first course. Additionally, the product of the first leukapheresis contained significantly fewer CD34+ cells in those mobilized after a second course only in group B, with no differences in group A. Nevertheless, the final products harvested did not differ in the content of MNC, CFU-GM and CD34+ cells, suggesting that these differences are not clinically important. These results indicate that the use of low-dose G-CSF (50 microg/m2/day) is as effective as 5 microg/kg/day in accelerating neutrophil recovery and mobilizing CD34+ cells after a first cycle of IAPVP-16 salvage chemotherapy, resulting in a substantial decrease in costs, while more heavily pretreated patients may require higher doses of G-CSF for an equivalent mobilization.

Isolation of CD34+ hematopoietic progenitor cells in chronic myeloid leukemia by magnetic activated cell sorting (MACS).

We have evaluated an easy and fast immunomagnetic method for positive selection of cells expressing the CD34 antigen from BM, peripheral blood (PB) and apheresis products (AP) of CML patients and healthy adults (HA) in order to further characterize them by immunophenotypic analysis. From an initial frequency of CD34+ cells in the original sample of 1.8 +/- 1.7%, CD34+ cells were rapidly and efficiently enriched up to 91.5 +/- 6.4% by high-gradient magnetic cell sorting (MACS) (yield 53 +/- 21%). A five-dimensional flow cytometric analysis of the immunomagnetic isolated CD34+ cells demonstrated little overlap between CD34+HLA-DRlo and CD34+CD38lo subpopulations in both BM-HA and in BM-CML. Only 16 and 6% of the CD34+HLA-DRlo and CD34+CD38lo cells respectively, showed lack of expression of both Ag (CD34+HLA-DRloCD38lo) in BM-CML samples. Between 60 and 70% of the CD34+ cells expressed the stem cell factor (SCF) receptor (c-KIT, CD117) and there were no differences between BM-HA and BM-CML patients. Moreover, more than 60% of the CD34+HLA-DRlo cells, co-expressed c-KIT. MACS-enriched BM-CD34+ cells showed normal hematopoietic colony formation in vitro in all the sources analyzed with a higher colony-forming efficiency than the unfractionated sample (MNC).

Expression of phosphatidylinositol anchored membrane proteins in paroxysmal nocturnal haemoglobinuria after bone marrow transplantation.

A 20-year-old male with severe bone marrow failure associated with paroxysmal nocturnal haemoglobinuria (PNH) underwent an allogeneic bone marrow transplantation (BMT). Flow cytometric analysis of phosphatidylinositol (PI) anchored membrane proteins prior to BMT showed a markedly reduced expression of monocyte CD14 and neutrophil CD16 molecules. On day +17 after BMT expression of both antigens reached normal values and remained stable throughout a follow-up period of 10 months, thus confirming the eradication of the PNH clone. To date, this is the first case in which normal expression of PI-anchored proteins after BMT is reported.

Imprecision of counting CFU-GM colonies and CD34-expressing cells.

Determinations of committed haemopoietic progenitor cells, namely CFU-GM (colony-forming unit-granulocyte/macrophage) and of CD34-expression haemopoietic cells as assessed by multiparameter flow cytometry are routine diagnostic tools in haemopoietic cell therapy. Generally, the tests are used to optimise the timing and management of cytapheresis and to assess the engraftment potential of the harvested cells. Both measurements, however, are at best surrogate markers, as an adequate routine test which effectively assesses the short- and long-term repopulating haemopoietic cell is not available. Nonetheless, cell threshold doses have been established. Above these thresholds rapid engraftment is almost invariable but below these thresholds the outcome is variable. In this study we have focussed on the imprecision in counting haemopoietic cells, as assessed as CFU-GM and as CD34-expressing cells. The data on both tests have been analysed from six European institutions. The coefficient of variation in CFU-GM colony counting was about 30%, whereas the coefficient of variation in flow cytometric counting of CD34-expressing cells was about 10%. These data suggest that the technical imprecision in enumerating progenitor cells, particularly CFU-GM, at low levels, might make a major contribution to the clinical variability observed after transplantation of sub-threshold progenitor cell dose.

Native valve endocarditis due to Candida parapsilosis: a late complication after bone marrow transplantation-related fungemia.

A case of Candida parapsilosis endocarditis observed 16 months after BMT is reported. The patient, a 35-year-old female with CML, suffered from Candida parapsilosis fungemia on day +22 after BMT. In spite of treatment with amphotericin B, fluconazole and catheter withdrawal, the same yeast was isolated > 1 year later from a vegetation on an old rheumatic mitral valve. Although the patient remained in complete cytogenetical and hematological remission, in vitro tests showed reduced phagocytic and chemotactic capacity of neutrophils and monocytes. This case stresses the need of prolonged therapy for patients with candidemia after BMT.

Infectious complications in 126 patients treated with high-dose chemotherapy and autologous peripheral blood stem cell transplantation.

The effect of an extensive prophylactic antimicrobial regimen was prospectively assessed in 126 patients after high-dose chemotherapy and autologous PBSC. They received ciprofloxacin (500 mg/12 h), acyclovir (200 mg/6 h), and itraconazole (200 mg/12 h) orally until neutrophil recovery. Febrile patients received i.v. imipenem (500 mg/6 h) to which vancomycin and amikacin were added if fever persisted for 2-3 and 5 days, respectively. Amphotericin B lipid complex was further given on day 7 or 8 of fever. Median times for a neutrophil count of >0.5 x 10(9)/l and a platelet count of >20 x 10(9)/l were 9 and 11 days. Severe neutropenia (<0.1 x 10(9)/l) lasted for a median of 5 days in which 72% of febrile episodes and 50% of cases of bacteremia occurred. Gram-positive bacteria were isolated in 30 of 40 episodes of bacteremia, 25 of which were caused by Staphylococcus epidermidis. Clinical foci were the intravascular catheter in 35 cases, respiratory infection in 11, cellulitis in two, anal abscess in one, and neutropenic enterocolitis in one. The high incidence of febrile episodes (94%) and bacteremias (31%) may be due to the lack of efficacy of antimicrobial prophylaxis and the persistence of a 5-day period of severe neutropenia.

Low-dose donor CD8+ cells in the CD4-depleted graft prevent allogeneic marrow graft rejection and severe graft-versus-host disease for chronic myeloid leukemia patients in first chronic phase.

Based on previous experiences in animals and humans, low doses of CD8+ lymphocytes infused together with the marrow graft seem to enhance engraftment after allogeneic T cell-depleted marrow transplantation. From April 1994 to February 1997, 12 patients with chronic myelogenous leukemia in first chronic phase receiving a bone marrow transplant (BMT) from an HLA-identical sibling were included in a pilot study of T cell subset depletion. Total depletion of CD4+ cells of the marrow graft and partial depletion of CD8+ cells was performed by immunomagnetic separation. In order to improve the engraftment rate, we infused a low fixed number of CD8+ lymphocytes (0.25 x 10(6)/kg). All the patients were at high risk of developing acute graft-versus-host disease (GVHD), with a recipient age of >30 years, and/or donor sensitized by previous pregnancies or transfusions. All of them received cyclosporin A and methotrexate post-BMT. No graft failure was observed. The grade III-IV GVHD rate was 16.6%, and the actuarial survival at 3 years is 81.8%. Immunological recovery showed persistent CD8+ HLA-DR+ lymphocytosis 8 months after transplant. Relapses were not observed. This experience shows the importance of CD8+ cells to ensure correct engraftment, decreasing the GVHD rate.

Mobilization of peripheral stem cells with intensive chemotherapy (ICE regimen) and G-CSF in chronic myeloid leukemia.

Seventeen patients with Philadelphia (Ph) chromosome-positive chronic myeloid leukemia (CML) were treated with the ICE regimen plus G-CSF with the aim of mobilizing and collecting Ph-negative peripheral stem cells (PSC) in the setting of an autotransplant program. Fifteen patients had CML in first chronic phase (CP), and two in accelerated phase (AP). Three patients had been previously treated with interferon alpha 2a (IFN). Twelve patients underwent leukaphereses and a mean of 4.7 x 10(8)/kg mononuclear cells were obtained. Four CP patients did not show a significant mobilization peak of CD34+ cells and leukapheresis was not performed; finally, one patient died before apheresis could be performed. Six of the 12 who underwent leukaphereses obtained more than 1.0 x 10(6)/kg CD34+ cells. Eight of the 12 mobilized patients (67%) obtained a major cytogenetic response, including two complete and six partial; in the remaining four patients minimal or absent cytogenetic responses were observed. A higher rate of Ph purging was obtained in patients mobilized early or showing residual Ph-negative cells before mobilization, even if they were in AP. Infectious complications were frequent with a 38% rate of bacteremia recorded and one case of pulmonary aspergillosis resulting in a toxicity similar to that occurring in acute myeloid leukemia-induction chemotherapy. The ICE regimen can promote 'in vivo' purging of the Ph+ cells in 67% of CML mobilized patients (8/12). Failure of mobilization occurs in 65% of patients (11/17), mainly because of poor CD34+ cell yield.