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Eleven uraemic patients were treated with recombinant human erythropoietin (rHuEpo). Seven haemodialysis patients and four peritoneal dialysis patients received a starting dose of 80 IU/kg i.v. and 40 IU/kg s.c. respectively, thrice weekly. The number of burst-forming-unit erythroid (BFU-E), colony-forming-unit erythroid (CFU-E), granulocyte-monocyte (CFU-GM) and megakaryocyte (CFU-Mk) were assayed 2 weeks before (DO), and 1 (M1) and 6 months (M6) after the initiation of rHuEpo treatment by means of a commonly applied clonal assay. All the patients showed the same haematopoietic response. A significant increase of CFU-E and CFU-Mk could be observed within 1 month of treatment. At this time, no significant modification was observed in BFU-E and CFU-GM number. At the 6th month the increase of CFU-E was maintained, whereas a significant fall of BFU-E, CFU-GM and CFU-Mk was observed. These results suggest that effects of rHuEpo are not restricted to the erythroid lineage but that erythropoietin might also act as a co-factor of megakar-yopoiesis. In the long term erythropoietin might induce erythroid differentiation in multipotent progenitor cells at the expense of the non-erythroid progenitors. [ABSTRACT FROM PUBLISHER]

Background: Polyclonal hypergammaglobulinaemia (PH) represents a classic diagnosis problem in internal medicine. However, there is no consensus threshold for PH. The aim of this study was to define a threshold for PH., Methods: We conducted a retrospective multicentric study using laboratory biological databases between 1 January 2016 and 31 December 2016 in two university hospitals and one non-university hospital. All patients 18 years old or over and with at least one serum protein electrophoresis (SPE) available in 2016 were included. Exclusion criteria were monoclonal, biclonal, or oligoclonal spikes or, in case of hypogammaglobulinaemia, proven free light chain gammopathy. The main endpoint was to define the threshold values for PH in this population. Another objective was to define the 95th percentile of the distribution., Results: 20 766 SPEs were included in this cohort. The PH threshold on 95th percentile was 18.9 g/L. The threshold varied according to geographical areas., Conclusions: This is the first study to scientifically define a PH threshold. The main limitation is that our threshold is only biological. The study was not designed to associate this threshold with a clinically active disease. In conclusion, while the 19 g/L cut-off seems the most relevant threshold, but it will need to be validated by prospective studies., (© The Author(s) 2022. Published by Oxford University Press on behalf of Postgraduate Medical Journal. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Introduction: Oral Squamous Cell Carcinomas (OSCC) are mostly related to tobacco consumption eventually associated to alcohol (Smoker/Drinker patients: SD), but 25-30% of the patients have no identified risk factors (Non-Smoker/Non-Drinker patients: NSND). We hypothesized that these patients have distinguishable immune profiles that could be useful for prognosis., Materials and Methods: Cells present in immune tumor microenvironment (TME) and blood from 87 OSCC HPV-negative patients were analyzed using a multiparameter flow cytometry assay, in a prospective case-control study. Cytokine levels in tumor supernatants and blood were determined by a cytometric bead array (CBA) assay., Results: Normal gingiva and blood from healthy donors (HD) were used as controls. A significant increase of granulocytes (p<0.05 for blood), of monocytes-macrophages (p<0.01 for blood) and of CD4 + T cells expressing CD45RO and CCR6 (p<0.001 for blood; p<0.0001 for TME) as well as higher levels of IL-6 (p<0.01 for sera, p<0.05 for tumor supernatant) were observed in SD patients as compared to NSND OSCC patients and HD. High percentages of CD4 + T cells expressing CD45RO and CCR6 cells in tumor tissue (p=0.05) and blood (p=0.05) of SD OSCC patients were also associated with a poorer prognosis while a high percentage of regulatory T cells (Treg) in tumor tissue was associated with a more favorable prognostic factor (p=0.05). Also, a higher percentage of blood CD8 + T lymphocytes among CD45 + cells in NSND patients was associated with a better disease-free survival (p=0.004)., Conclusion: Granulocytes, monocytes-macrophages, and CD4 + T cells expressing CD45RO and CCR6 in blood and TME as well as serum IL-6 can therefore distinguish OSCC SD and NSND patients. Quantifying the proportion of CD4 + T cells expressing CD45RO and CCR6 and of Treg in SD patients and CD8 + T cells in NSND patients could help defining the prognostic of OSCC patients., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Rochefort, Karagiannidis, Baillou, Belin, Guillot-Delost, Macedo, Le Moignic, Mateo, Soussan, Brocheriou, Teillaud, Dieu-Nosjean, Bertolus, Lemoine and Lescaille.)

Background: Polyclonal hypergammaglobulinaemia (PH) represents a classic diagnosis problem in internal medicine. However, there is no consensus threshold for PH. The aim of this study was to define a threshold for PH., Methods: We conducted a retrospective multicentric study using laboratory biological databases between 1 January 2016 and 31 December 2016 in two university hospitals and one non-university hospital. All patients 18 years old or over and with at least one serum protein electrophoresis (SPE) available in 2016 were included. Exclusion criteria were monoclonal, biclonal, or oligoclonal spikes or, in case of hypogammaglobulinaemia, proven free light chain gammopathy. The main endpoint was to define the threshold values for PH in this population. Another objective was to define the 95th percentile of the distribution., Results: 20 766 SPEs were included in this cohort. The PH threshold on 95th percentile was 18.9 g/L. The threshold varied according to geographical areas., Conclusions: This is the first study to scientifically define a PH threshold. The main limitation is that our threshold is only biological. The study was not designed to associate this threshold with a clinically active disease. In conclusion, while the 19 g/L cut-off seems the most relevant threshold, but it will need to be validated by prospective studies., (© The Author(s) 2022. Published by Oxford University Press on behalf of Postgraduate Medical Journal. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Chronic exposure to environmental pollutants is often associated with systemic inflammation. As such, cigarette smoking contributes to inflammation and lung diseases by inducing senescence of pulmonary cells such as pneumocytes, fibroblasts, and endothelial cells. Yet, how smoking worsens evolution of chronic inflammatory disorders associated with Th17 lymphocytes, such as rheumatoid arthritis, psoriasis, Crohn's disease, and multiple sclerosis, is largely unknown. Results from human studies show an increase in inflammatory CD4 + Th17 lymphocytes at blood- and pulmonary level in smokers. The aim of the study was to evaluate the sensitivity of CD4 + Th17 lymphocytes to cigarette smoke-induced senescence. Mucosa-homing CCR6 + Th17- were compared to CCR6 neg -and regulatory T peripheral lymphocytes after exposure to cigarette smoke extract (CSE). Senescence sensitivity of CSE-exposed cells was assessed by determination of various senescence biomarkers (β-galactosidase activity, p16 Ink4a - and p21 expression) and cytokines production. CCR6 + Th17 cells showed a higher sensitivity to CSE-induced senescence compared to controls, which is associated to oxidative stress and higher VEGFα secretion. Pharmacological targeting of ROS- and ERK1/2 signalling pathways prevented CSE-induced senescence of CCR6 + Th17 lymphocytes as well as VEGFα secretion. Altogether, these results identify mechanisms by which pro-oxidant environmental pollutants contribute to pro-angiogenic and pathogenic CCR6 + Th17 cells, therefore potential targets for therapeutic purposes.

Currently, there is a lack of systems for studying the role of hepatitis B viral proteins, such as HBeAg and HBcAg, on liver injury. It is necessary to develop an original tool in order to clarify the role of these viral proteins in hepatic stellate cell activation, and to understand the molecular mechanisms of liver injury. HepaRG are the most reliable hepatocyte-like cells for studying liver functions or disorders. In this paper, we demonstrate that the transduction of differentiated HepaRG (dHepaRG) cells can be performed successfully using lentiviral particles. The production of a functional Green Fluorescent Protein (GFP) assessed by Fluorescence Activated Cell Sorting and fluorescence microscopy is up to 16% of GFP positive cells using a multiplicity of infection (MOI) of 2.4. We demonstrate that this technology can allow the stable expression of GFP during the long lifecycle of the cell (up to four weeks after the cell's passage). With this innovative tool, we aim to express viral proteins such as HBeAg or HBcAg in dHepaRG cells. The preliminary results of this work shows that HBeAg can be efficiently produced in dHepaRG cells and that increased MOI allows a better production of this protein. Our future objective will be to study the role of HBc and HBe proteins on the induction of hepatic fibrosis.

Langerhans cell histiocytosis (LCH) and the non-LCH neoplasm Erdheim-Chester disease (ECD) are heterogeneous neoplastic disorders marked by infiltration of pathologic macrophage-, dendritic cell-, or monocyte-derived cells in tissues driven by recurrent mutations activating MAPK signaling. Although recent data indicate that at least a proportion of LCH and ECD patients have detectable activating kinase mutations in circulating hematopoietic cells and bone marrow-based hematopoietic progenitors, functional evidence of the cell of origin of histiocytosis from actual patient materials has long been elusive. Here, we provide evidence for mutations in MAPK signaling intermediates in CD34 + cells from patients with ECD and LCH/ECD, including detection of shared origin of LCH and acute myelomonocytic leukemia driven by TET2 -mutant CD34 + cell progenitors in one patient. We also demonstrate functional self-renewal capacity for CD34 + cells to drive the development of histiocytosis in xenotransplantation assays in vivo. These data indicate that the cell of origin of at least a proportion of patients with systemic histiocytoses resides in hematopoietic progenitor cells prior to committed monocyte/macrophage or dendritic cell differentiation and provide the first example of a patient-derived xenotransplantation model for a human histiocytic neoplasm., (© 2017 by The American Society of Hematology.)

Despite current therapy, head and neck squamous cell carcinomas (HNSCCs) arising from various mucosal sites of the upper aero-digestive tract frequently relapse in a loco-regional manner and have a poor prognosis. Our objective was to validate an innovative mucosal route of vaccination using plasmo virus-like particles (pVLPs) in a pre-clinical orthotopic model of HNSCCs. For this purpose, we used pVLP-E7, that are plasmid DNA encoding retroviral virus-like particles carrying a truncated E7 oncoprotein from HPV-16 as antigen model, to vaccinate mice bearing pre-established TC-1 tumors implanted into the buccal mucosa. pVLP-E7 were combined with clinical grade TLR agonists (Imiquimod and CpG-ODN). In this pre-clinical orthotopic model, whose tumor microenvironment resembles to those of human HNSCCs, different mucosal vaccination routes were tested for their ability to elicit efficient immune and antitumoral responses. Results showed that mucosal intra-cheek (IC) vaccinations using pVLP-E7, comparatively to intradermic vaccinations (ID), gave rise to higher mobilization of mucosal (CD49a(+)) CD8(+) specific effector T cells in both tumor draining lymph nodes (TdLNs) and tumor microenvironment resulting in better antitumor effects and in a long-term protection against tumor rechallenge. In vivo CD8(+) depletion demonstrated that antitumoral effects were fully dependent upon the presence of CD8(+) T cells. Validation of IC mucosal vaccinations with pVLPs combined with adjuvants using a pre-clinical orthotopic model of HNSCC provides valuable pre-clinical data to rapidly envision the use of such therapeutic vaccines in patients with HNSCCs, inasmuch as vaccinal components and adjuvants can be easily obtained as clinical grade reagents.

Natural regulatory T cells (Tregs) may have a great therapeutic potential to induce tolerance in allogeneic cells and organ transplantations. In mice, we showed that alloantigen-specific Tregs (spe-Tregs) were more efficient than polyclonal Tregs (poly-Tregs) in controlling graft-versus-host disease (GVHD). Here we describe a clinical-grade compliant method for generating human spe-Tregs. Tregs were enriched from leukapheresis products with anti-CD25 immunomagnetic beads, primed twice by allogeneic mature monocyte-derived dendritic cells (mDCs), and cultured during 3 weeks in medium containing interleukin 2 (IL-2), IL-15, and rapamycin. After 3 weeks of culture, final cell products were expanded 8.3-fold from the initial CD25(+) purifications. Immunophenotypic analyses of final cells indicate that they were composed of 88 ± 2.6% of CD4(+) T cells, all expressing Treg-specific markers (FOXP3, Helios, GARP, LAP, and CD152). Spe-Tregs were highly suppressive in vitro and also in vivo using a xeno-GVHD model established in immunodeficient mice. The specificity of their suppressive activity was demonstrated on their ability to significantly suppress the proliferation of autologous effector T cells stimulated by the same mDCs compared to third-party mDCs. Our data provide evidence that functional alloantigen Tregs can be generated under clinical-grade compliant conditions. Taking into account that 130 × 10(6) CD25(+) cells can be obtained at large scale from standard leukapheresis, our cell process may give rise to a theoretical final number of 1 × 10(9) spe-Tregs. Thus, using our strategy, we can propose to prepare spe-Tregs for clinical trials designed to control HLA-mismatched GVHD or organ transplantation rejection.

Gene-directed enzyme prodrug therapy (GDEPT) consists in targeted delivery to tumor cells of a suicide gene responsible for in situ conversion of a prodrug into cytotoxic metabolites. One of the major limitations of this strategy in clinical application was the poor prodrug activation capacity of suicide gene. We built a highly efficient suicide gene capable of bioactivating the prodrug cyclophosphamide (CPA) by fusing a CYP2B6 triple mutant with NADPH cytochrome P450 reductase (CYP2B6TM-RED). Expression of this fusion gene via a recombinant lentivirus (LV) vector converted resistant human (A549) and murine (TC1) pulmonary cell lines into CPA-susceptible cell lines. We tested the efficiency of our GDEPT strategy in C57Bl/6 immunocompetent mice, using TC1 cells expressing the HPV-16 E6/E7 oncoproteins. In mice bearing tumors composed only of TC1-CYP2B6TM-RED cells, four CPA injections (140 mg/Kg once a week) completely eradicated the tumors for more than two months. Tumors having only 25% of TC1-CYP2B6TM-RED cells were also completely eradicated by five CPA injections, demonstrating a major in vivo bystander effect. Moreover, surviving mice were rechallenged with parental TC1 cells. The tumors regressed spontaneously 7 days after cell inoculation or grew more slowly than in control naive mice due to a strong immune response mediated by anti-E7CD8(+)T cells. These data suggest that combining the CYPB6TM-RED gene with CPA may hold promise as a highly effective treatment for solid tumors in humans.

Human papillomavirus (HPV) is involved in the development of anogenital tumors and also in the development of oropharyngeal head and neck carcinomas, where HPV-16, expressing the E6 and E7 oncoproteins, is the most frequent serotype. Although vaccines encoding L1 and L2 capsid HPV proteins are efficient for the prevention of HPV infection, they are inadequate for treating established tumors. Hence, development of innovative vaccine therapies targeting E6/E7 is important for controlling HPV-induced cancers. We have engineered a nononcogenic mutated E7-specific plasmo-retroVLP vaccine (pVLP-E7), consisting of plasmid DNA, that is able to form recombinant retrovirus-based virus-like particles (VLPs) that display E7 antigen into murine leukemia virus Gag proteins pseudotyped with vesicular stomatitis virus envelope glycoprotein (VSV-G). pVLP-E7 vaccinations were studied for their ability to generate specific immune responses and for induction of protective immunity against tumor cell challenge in preventive and therapeutic models. The produced VLPs induce the maturation of human dendritic cells in vitro and mount specific E7 T cell responses. Intradermic vaccinations of mice with pVLP-E7 show their efficacy to generate antigen-specific T cell responses, to prevent and protect animals from early TC-1 tumor development compared with standard DNA or VLP immunizations. The vaccine efficacy was also evaluated for advanced tumors in mice vaccinated at various time after the injection of TC-1 cells. Data show that pVLP-E7 vaccination can cure mice with already established tumors only when combined with Toll-like receptor-7 (TLR7) and TLR9 agonists. Our findings provide evidence that pVLPs, combining the advantages of DNA and VLP vaccines, appear to be a promising strategy for the treatment of HPV-induced cancers.

By revisiting CD90, a GPI-anchored glycoprotein, we show that CD90 is expressed by a subset of CD4(+) and CD8(+) human T cells. CD4(+)CD90(+) cells share similarities with Th17 cells because they express the Th17-specific transcription factor RORC2 and produce IL-17A. CD4(+)CD90(+) cells are activated memory T cells that express the gut mucosal markers CCR6, CD161, and the α(4) and β(7) integrins. Compared with CD90-depleted CCR6(+) memory Th17 cells, CD4(+)CD90(+) cells express higher levels of IL-22 and proinflammatory cytokines (IL-6, TNF-α and GM-CSF), but they produce lower levels of IL-21 and no IL-9. Analyses of CD8(+)CD90(+) cells reveal that they express RORC2 and are able to produce higher levels of IL-17A, IL-22, and CCL20 compared with CD90-depleted CD8(+) cells. These data show that CD90 identifies Th17 and Tc17 cells with a peculiar cytokine profile. Studies of circulating CD90(+) cells in HIV patients show that CD90(+) cells are decreased with an imbalance of the CD4(+)CD90(+)/regulatory T cell ratio in nontreated patients compared with treated patients and healthy donors. Overall, human CD90 identifies a subset of Th17 and Tc17 cells within CD4(+) and CD8(+) T cells, respectively, which are depleted during HIV infection.

Recipient-specific regulatory T cells (rsTreg) can prevent graft-versus-host disease (GVHD) by inhibiting donor T-cell expansion after hematopoietic stem cell transplantation (HSCT) in mice. Importantly, in adult humans, because of thymus involution, immune reconstitution during the first months after HSCT relies on the peripheral expansion of donor T cells initially present in the graft. Therefore, we developed a mouse model of HSCT that excludes thymic output to study the effect of rsTreg on immune reconstitution derived from postthymic mature T cells present within the graft. We showed that GVHD prevention with rsTreg was associated with improvement of the limited immune reconstitution compared with GVHD mice in terms of cell numbers, activation phenotype, and cytokine production. We further demonstrated a preserved in vivo immune function using vaccinia infection and third-party skin-graft rejection models, suggesting that rsTreg immunosuppression was relatively specific of GVHD. Finally, we showed that rsTreg extensively proliferated during the first 2 weeks and then declined. In turn, donor Treg proliferated from day 15 on. Taken together, these results suggest that rsTreg GVHD prevention is associated with improved early immune reconstitution in a model that more closely approximates the biology of allogeneic HSCT in human adults.

The diversity of the human immune repertoire and how it relates to a functional immune response has not yet been studied in detail in humanized NOD.SCID.gammac(-/-) immunodeficient mice. Here, we used a multiplex PCR on genomic DNA to quantify the combinatorial diversity of all possible V-J rearrangements at the TCR-beta chain and heavy chain Ig locus. We first show that the combinatorial diversity of the TCR-beta chain generated in the thymus was well preserved in the periphery, suggesting that human T cells were not vastly activated in mice, in agreement with phenotypic studies. We then show that the combinatorial diversity in NOD.SCID.gammac(-/-) mice reached 100% of human reference samples for both the TCR and the heavy chain of Ig. To document the functionality of this repertoire, we show that a detectable but weak HLA-restricted cellular immune response could be elicited in reconstituted mice after immunization with an adenoviral vector expressing HCV envelope glycoproteins. Altogether, our results suggest that humanized mice express a diversified repertoire and are able to mount antigen-specific immune responses.

Background: Human CD4+CD25+FOXP3+ natural regulatory T-cells (nTreg) have a great therapeutic potential for the induction of tolerance in allo-transplanted patients or for the control of severe auto-immune diseases. However, clinical-grade production of nTreg remains difficult to achieve because of the absence of a truly specific surface marker and of their low frequency that implies a need for their ex vivo expansion. Furthermore, safety issues should be taken into consideration due to the risk of either uncontrolled nTreg-induced immunosuppression or uncontrolled proliferation of autoreactive contaminating T-cells particularly in an auto-immune context., Methods: We compared different clinical-grade conditions for immuno-magnetic selection and ex vivo expansion of nTreg. For safety, expanded cells were genetically modified with retroviral vectors co-expressing human CD90 and HSV1 thymidine kinase. The CD90 surface marker and thymidine kinase allow for selection and elimination of transduced cells by ganciclovir, respectively., Results: We showed that (i) nTreg could be enriched in a one step using CD25 microbeads, were functionally suppressive and mainly FOXP3+; (ii) using anti-CD28- and anti-CD3-coated beads, interleukin-2 and rapamycin, nTreg were expanded 150-200-fold after 3 weeks. Under these clinical-grade conditions, they remained suppressive, and no major alteration of the TCR repertoire was observed; (iii) after efficient retroviral transduction and CD90 selection, nTreg maintained their suppressive activity; (iv) transduced nTreg could be eliminated by ganciclovir upon activation., Conclusions: The efficient procedure reported here for the preparation of nTreg, whose safety has been ensured, is now applicable for further clinical trials., ((c) 2008 John Wiley & Sons, Ltd.)

Many strategies have been proposed to circumvent cancer development or prevent its growth. One of the promising strategies is to direct the immune response toward tumour antigens. This can be achieved by loading dendritic cells, the most potent antigen presenting cells, with tumour antigens. Fusion of dendritic cells (DC) with tumour cells is an attractive way to load the DC with all tumour antigens regardless of their immunogenicity status and the fact that they have, or not, been identified. The aim of our study was to characterise the immunophenotype of fused cells, monitor the evolution of the fusion interface and the distribution of surface antigens over time and assess for their maturation status and functionality in vitro. We used polyethylene glycol to fuse DC with Her2/neu positive breast cancer cell line T-47D. We demonstrate that false positive events accounted in flow cytometry can be identified using confocal microscopy to avoid an overestimation of fusion efficiency and to distinguish clearly hybrid cells from aggregated or phagocytosed cells. We used imaging means to demonstrate the conservation of presentation molecules (MHC II, CD1a), co-stimulatory molecules (CD40, CD80, CD86), as well as tumour antigens (Her2/neu, cytokeratins) in optimised conditions. Fused cells were only recognisable for 48 h as assessed by membrane staining and membranous antigen distribution. Fusion was necessary for their maturation to be accompanied by functional activity such as secretion of cytokines and perforin. These results suggest that hybrid cells generated by the fusion of DC and tumour cells can be easily identified and characterised using imaging techniques, and that, regarding functionality and cytokine secretion, they appear to be good candidates for anti-tumour therapies namely in breast cancer.

Objective: Studies in mice have reported contradictory results on the contribution of bone marrow cells to myocardial regeneration. This study aims to evaluate their ability to differentiate into cells of cardiac lineage in a nonhuman primate mode of myocardial infarct., Materials and Methods: Lin(-)CD34(-) and CD34(+)-enriched bone marrow cells or mobilized peripheral blood cells were transduced with green fluorescent protein (GFP) and injected directly into ischemic myocardium. The fate of the transplanted cells was evaluated using quantitative reverse transcription polymerase chain reaction (QRT-PCR) and immunohistology. Animals were followed-up using echocardiography., Results: QRT-PCR analysis detected from 3% to 10% of the original number of administered GFP(+) cells after 7 days. These GFP(+) cells did not express cardiac tissue-specific markers, but were immunophenotypically consistent with undifferentiated hematopoietic cells. The local production of vascular endothelial growth factor, measured by QRT-PCR, was approximately doubled as compared to the untreated infarcted control heart. Three months after hematopoietic stem cell (HSC) administration, no GFP(+) cells were detected and no evidence of regeneration of the infarcted region was found by histological examination. In contrast, a high level of matrix metalloproteinase 2 was measured in infarct and peri-infarct area. At this time, an improved ejection fraction and decreased left ventricular chamber dimension, which might be also related to a natural course after reperfusion, were observed., Conclusions: Our data show that GFP(+) CD34(+) and Lin(-)CD34(-)-enriched HSC do not differentiate into cardiomyocytes or into endothelial cells in the infarcted myocardium and that the local production of some growth factors had no positive effect on myocardial regeneration after 3 months.

In humans, the CD4 molecule is expressed on a subset of T-cells and at various levels on myeloid and lymphoid cells. The mechanisms regulating human CD4 gene expression are yet poorly understood. We speculated that the CD4 silencer, which operates in CD8+ T-cells to repress CD4 expression, could be responsible for CD4 repression in human lymphoid non-T-cells. To test this possibility, we used lentiviral vectors carrying CD4 regulatory sequences, with or without the silencer element, to express an eGFP reporter gene. We observed that (i) in the absence of the silencer element, eGFP expression was detected in CD34+-derived B- and NK-cells that otherwise lacked endogenous CD4 mRNA, indicating active repression of the CD4 regulatory sequences and (ii) the addition of the CD4 silencer could repress eGFP expression in these same cells, as well as in human B-cells generated in vivo in NOD/SCID mice. Collectively, our results suggest that beyond its well-characterized function in T-cells, the CD4 silencer also regulates CD4 gene expression in human lymphoid non-T-cells.

Background: Lentiviral gene transfer into hematopoietic cells has been mostly optimized with vectors carrying a single reporter gene. For many clinical applications, lentiviral vectors should contain more than one gene because transduced cells should be enriched by a selectable marker or killed for safety reasons after use. Thus, we compared various vectors containing a bicistronic cassette driven by different ubiquitous promoters for their ability to transduce human T-lymphocytes, CD34+-cells, and dendritic cells (DCs) derived from CD34+-cells or monocytes., Methods: We designed HIV or SIV constructs containing a bicistronic cassette composed of two reporter genes (thy1/GFP) linked by an internal ribosome entry site sequence and driven by the cytomegalovirus (CMV) or elongation factor 1alpha (EF1alpha) promoters. The woodchuck hepatitis virus post-transcriptional regulatory element (WPRE) was or not inserted within the constructs, the Vpx accessory protein was or not used for SIV vectors. Target cells were infected at the same multiplicity of infection, transduction efficiency was analyzed both by flow cytometry and vector integration., Results: For T-cells, HIV-based vectors/WPRE+ in which the thy1/GFP cassette was driven by the EF1alpha promoter were more efficient than SIV-based vectors. For CD34+-cells and CD34+-derived DCs, better thy1/GFP expression was achieved when the CMV promoter drove the cassette inserted into HIV-based vectors/WPRE+. Conversely, for monocyte-derived DCs, the cassette yielded better thy1/GFP expression when inserted into SIV-based vectors/WPRE+ and driven by the CMV or EF1alpha promoters, the use of Vpx significantly improving the expression levels., Conclusions: Our results provide guidelines for improving the transduction of T-cells, CD34+-cells or DCs with lentiviral bicistronic vectors designed for clinical applications., (Copyright (c) 2005 John Wiley & Sons, Ltd.)

The early stages of human lymphopoiesis are poorly characterized. Here, we compared the lymphoid potential of a novel umbilical cord blood CD34(+)CD45RA(hi)CD7(+) hematopoietic progenitor cell (HPC) population with that of CD34(+)CD45RA(hi)Lin(-)CD10(+) HPCs, previously proposed as candidate common lymphoid progenitors. Limiting-dilution and clonal analysis, fetal thymic organ cultures, and culture onto Notch ligand Delta-like-1-expressing OP9 cells, showed that although CD34(+)CD45RA(hi)CD7(+) HPCs could generate cells of the 3 lymphoid lineages, their potential was skewed toward the T/natural killer (T/NK) lineages. In contrast, CD34(+)CD45RA(hi)Lin(-)CD10(+) HPCs predominantly exhibited a B-cell potential. Gene expression profiling with DNA microarrays confirmed that CD34(+)CD45RA(hi)CD7(+) HPCs selectively expressed T-lymphoid and NK lineage-committed genes while retaining expression of genes affiliated to the granulomonocytic lineage, whereas CD34(+)CD45RA(hi)Lin(-)CD10(+) HPCs displayed a typical pro-B-cell transcription profile and essentially lacked genes unrelated to the B lineage. In addition, both populations could be generated in vitro from CD34(+)CD45RA(int)CD7(-) and CD34(+)CD45RA(hi)Lin(-) HPCs with mixed lymphomyeloid potential, from which they emerged independently with different growth/differentiation factor requirements. These findings indicate that CD34(+)CD45RA(hi)CD7(+) and CD34(+)CD45RA(hi)Lin(-)CD10(+) HPCs correspond to multipotent early lymphoid progenitors polarized toward either the T/NK or B lineage, respectively.

Objectives: To study, in asymptomatic HIV-1-infected (HIV+) patients, whether peripheral blood hematopoietic progenitor/stem cells (PBPC) mobilized by granulocyte colony stimulating factor (G-CSF), can be used as a source of cells for retroviral gene therapy., Design: PBPC from two groups of HIV+ patients (treated or untreated by highly active antiretroviral therapy) and from seronegative donors were mobilized with G-CSF., Methods: PBPC collected by leukapheresis were enriched for CD34 cells, immunophenotypically and functionally characterized, cultured and infected with retroviral vectors. HIV proviral integration was studied on fresh and cultured cells., Results: G-CSF moderately and transiently increased the viral load in untreated patients only, and induced in both groups of HIV+ patients mobilization of percentages and numbers of CD34 cells comparable to those of seronegative volunteers. The most immature CD34 cell subset, the clonogenic progenitor and long-term culture initiating cells were significantly decreased in leukapheresis products and CD34-enriched fractions from untreated HIV+ patients but not in those from treated HIV+ patients. Cell cycle activation and growth factor responses of CD34 cells from both groups of HIV+ patients were not different from those of the control group. Culture and retroviral infection of CD34 cells from HIV+ patients did not enhance HIV replication, and yielded transduction levels similar to those obtained using CD34 cells from seronegative donors., Conclusions: G-CSF-mobilized PBPC can be safely used for HIV retroviral gene therapy in asymptomatic treated patients while highly active antiretroviral therapy would control the G-CSF-induced increase in viral load and correct the defective hematopoiesis observed in untreated patients, without inhibiting the retroviral transduction of PBPC.