Acute hantavirus infection presenting as haemolytic-uraemic syndrome (HUS): the importance of early clinical diagnosis

The European prototype of hantavirus, Puumala virus (PUUV), isolated from a common wild rodent, the bank vole (Myodes glareolus), causes nephropathia epidemica (NE). NE can perfectly mimic haemolytic-uraemic syndrome (HUS), progressing from an aspecific flu-like syndrome to acute kidney injury with thrombocytopaenia, and presenting with some signs of haemolytic anaemia and/or coagulopathy. Moreover, both NE and HUS can occur in local outbreaks. We report an isolated case of NE, initially referred for plasmapheresis for suspected HUS, although signs of overt haemolysis were lacking. Early suspicion of hantavirus infection, later confirmed by serology and reverse transcription polymerase chain reaction (RT-PCR), prevented subsequent excessive treatment modalities.

Characterization of Interleukin-15-Transpresenting Dendritic Cells for Clinical Use

Personalized dendritic cell- (DC-) based vaccination has proven to be safe and effective as second-line therapy against various cancer types. In terms of overall survival, there is still room for improvement of DC-based therapies, including the development of more immunostimulatory DC vaccines. In this context, we redesigned our currently clinically used DC vaccine generation protocol to enable transpresentation of interleukin- (IL-) 15 to IL-15Rβγ-expressing cells aiming at boosting the antitumor immune response. In this study, we demonstrate that upon electroporation with both IL-15 and IL-15Rα-encoding messenger RNA, mature DC become highly positive for surface IL-15, without influencing the expression of prototypic mature DC markers and with preservation of their cytokine-producing capacity and their migratory profile. Functionally, we show that IL-15-transpresenting DC are equal if not better inducers of T-cell proliferation and are superior in tumor antigen-specific T-cell activation compared with DC without IL-15 conditioning. In view of the clinical use of DC vaccines, we evidence with a time- and cost-effective manner that clinical grade DC can be safely engineered to transpresent IL-15, hereby gaining the ability to transfer the immune-stimulating IL-15 signal towards antitumor immune effector cells.

Medical costs of treatment and survival of patients with acute myeloid leukemia in Belgium

The advent of new cell-based immunotherapies for leukemia offers treatment possibilities for certain leukemia subgroups. The wider acceptability of these new technologies in clinical practice will depend on its impact on survival and costs. Due to the small patient groups who have received it, these aspects have remained understudied. This non-randomized single-center study evaluated medical costs and survival for acute myeloid leukemia between 2005 and 2010 in 50 patients: patients treated with induction and consolidation chemotherapy (ICT) alone; patients treated with ICT plus allogeneic hematopoietic stem cell transplantation (HCT), which is the current preferred post-remission therapy in patients with intermediate- and poor-risk AML with few co-morbidities, and patients treated with ICT plus immunotherapy using autologous dendritic cells (DC) engineered to express the Wilms' tumor protein (WT1). Total costs including post- consolidation costs on medical care at the hematology ward and outpatient clinic, pharmaceutical prescriptions, intensive care ward, laboratory tests and medical imaging were analyzed. Survival was markedly better in HCT and DC. HCT and DC were more costly than ICT. The median total costs for HCT and DC were similar. These results need to be confirmed to enable more thorough cost-effectiveness analyses, based on observations from multicenter, randomized clinical trials and preferably using quality-adjusted life-years as an outcome measure.

Immunotherapy in leukaemia

Therapeutic cancer vaccination, e.g. by using tumour antigen-presenting dendritic cells (DCs) that 'educate' the immune system to recognise and attack tumour cells, represents a new concept of treatment in oncology. DCbased immunotherapy elicits both innate (NK) and adaptive (T cells) cellular responses correlated with clinical benefit. WT1 mRNA-transfected DCs emerge as a feasible and effective strategy to control residual disease in acute myeloid leukaemia (AML), in particular as a post-remission treatment to prevent full relapse. This innovative approach takes advantage of the intrinsic potential of the immune system to eradicate malignant disease.

Dendritic cells in multiple sclerosis: key players in the immunopathogenesis, key players for new cellular immunotherapies?

Many studies have demonstrated the role of the adaptive immune system in the pathogenesis of multiple sclerosis (MS). Recent data suggest that dendritic cells (DCs), which are innate immune cells, also contribute to the pathogenesis of MS. In patients with MS, DCs are abundantly present in brain lesions, and display an altered phenotype and/or function as compared with this in healthy controls. DCs are thus in the position to pathologically influence the effector function of (auto-reactive) T and B cells. Interestingly, current first-line immunomodulating therapies for MS have been shown to restore DC phenotype and function, albeit in a non-specific manner. To date, clinical trials using agents specifically targeting DC function are ongoing. Moreover, several studies worldwide are currently investigating possible strategies to develop tolerogenic DCs. This review focuses on the phenotypic and functional alterations of conventional DCs and plasmacytoid DCs in patients with MS. Furthermore, we discuss how existing immunomodulating therapies for MS patients affect DC function and address future perspectives in the development of immunotherapies specifically targeting DCs.

A hypogranular variant of acute promyelocytic leukaemia showing a heterogenic immunophenotype with CD34, CD2, HLA-DR positivity: a case report and review of the literature

We report the case of a 46-year-old man who presented with the hypogranular variant of an acute promyelocytic leukaemia (APL). RT-PCR analysis for detection of the t(15;17) fusion transcript confirmed the cytological findings by demonstrating a bcr-3 type PML/RARalpha rearrangement. According to the WHO-classification, this leukaemia fulfilled the criteria for 'Acute promyelocytic leukaemia with t(15;17)(q22;q12)'(1). Immunophenotyping revealed a leukaemic population with an aberrant expression of markers. Besides the presence of the expected immunophenotypic markers in APL (CD45 with low density, CD13+, CD33+, CD15-, CD117+ and MPO+), the population showed a positivity for CD34, CD2 and HLA-DR for at least a part of the malignant promyelocytes. Since the expression of these three markers, all together, is rather unique, we reviewed the literature to prove the relationship of this specific immunophenotype with morphology, clinical and molecular findings.

Natural killer cell immune escape in acute myeloid leukemia

As central players of the innate immune system, natural killer (NK) cells can exert direct and indirect anti-tumor effects via their cytotoxic and immune regulatory capacities, pivotal in the induction of an effective adaptive anti-tumor immune response. Hence, NK cells are considered to be important in the immune surveillance of cancer. In acute myeloid leukemia (AML) patients, however, significantly impaired NK cell functions can facilitate escape from immune surveillance and affect patient outcome. Here, we review various NK cell defects and AML evasion mechanisms to escape from NK cell-mediated immune surveillance and we discuss NK cell-related parameters as prediction factors of AML patient outcome. On the basis of these observations, novel immunotherapeutic strategies capitalizing on the potentiation of NK cell functions have emerged in AML immunotherapy, as discussed in this review. Increased knowledge on AML escape routes from NK cell immune surveillance will further aid in the design of novel NK cell-based immunotherapy approaches for the treatment of AML.

Antibiotic management of febrile neutropenia: current developments and future directions

Mortality due to febrile neutropenia has decreased since the concept of empiric therapy became standard care. However, infectious complications remain the most common adverse events of chemotherapy. bacterial epidemiology has changed during the past decades. There is currently an increasing trend in infections due to Gramnegative bacteria which have higher rates of resistance for a variety of reasons.The use of biomarkers for diagnosis remains a domain of further investigation. Since the patient population with febrile neutropenia is very heterogeneous, models of risk assessment have been developed with the most commonly used today being the mASCC score.Oral antibiotic treatment seems to be appropriate in low-risk patients. In moderate or high-risk patients monotherapy is the most common option. However, due to emerging resistance this could change by next year. Some new antibiotics have been developed, but experience in the treatment of neutropenic fever is limited. The use of antibiotics for prophylaxis remains controversial, although recent studies suggest a reduction in death from all causes.

Quantification of IFN-gamma produced by human purified NK cells following tumor cell stimulation: comparison of three IFN-gamma assays

Interferon (IFN)-gamma released by natural killer (NK) cells has become a subject of major interest, given its importance in bridging the innate and adaptive immune system. Interestingly, reports concerning tumor cell stimulation of NK cells show divergent data on which stimuli induce IFN-gamma production. Here, the question remains whether tumor cell recognition is sufficient to trigger IFN-gamma or whether a second signal is required such as type I IFN. While IFN-gamma detection methods are abundantly used with peripheral blood mononuclear cells or purified T cell fractions as responder populations, only limited data is available about comparison of these assays with purified NK cells. In this study, we assessed the relationship between stimulation of human purified resting peripheral blood NK cells with one (tumor cell or IFN-alpha) and two (tumor cell+IFN-alpha) signals by measuring IFN-gamma using three different assays. We performed the enzyme-linked immunosorbent assay (ELISA), the enzyme-linked immunospot (ELISPOT) assay and intracellular cytokine staining (ICS) assay in parallel per donor and determined whether there was a correlation between these assays. Our results show that two-signal stimulation of human resting NK cells induces significantly more IFN-gamma as compared to one-signal stimulation, readily picked up by all assays. Moreover, statistical analysis points towards a positive correlation between these assays for IFN-gamma produced following two-signal stimulation. Importantly, we show that tumor cell stimulation alone is enough to trigger secretion of IFN-gamma, but this finding was only evidenced by ELISPOT. These results reveal that the choice of IFN-gamma detection method can markedly influence the outcome regarding induction of NK cell IFN-gamma by tumor cells.

Cefepime and amikacin as empirical therapy in patients with febrile neutropaenia: a single-centre phase II prospective survey

The aim of the survey was to prospectively evaluate the effectiveness of the combination therapy cefepime and amikacin in the initial treatment of haematology patients with febrile neutropaenia. Two hundred twenty (220) episodes of febrile neutropaenia were analysed in 54 males and 82 females (median age 58 years), most patients had a severe neutropaenia with in 72% of all periods a neutrophil count of less than 100. Microbiological infection was confirmed in 72 cases (32.8%). Sixty-one (61) bacteria were isolated from blood cultures of which 22 were identified as Gram-negative bacteria and 38 as Gram-positive bacteria. Sixty-three (63) episodes (28.6%) were clinically documented, 85 episodes (38.6%) were fever of unknown origin. Clinical cure was achieved in 123 febrile episodes (56%) after initiation of the current antibiotic protocol; another 22 patients (10%) became afebrile after modifying the initial antibiotic regimen 48 hours or longer after treatment initiation. In 61 cases (27.7%) there was persistent fever or re-occurrence of fever, these cases were considered as treatment failure. Eight patients (3.6%) died during the study. This survey has demonstrated that the combination therapy with cefepime and amikacin can be considered as an effective treatment for febrile neutropaenia in high-risk haematological patients in our centre with a high incidence of resistance to Gram-negative bacteria.

Immunosuppression induced by immature dendritic cells is mediated by TGF-beta/IL-10 double-positive CD4+ regulatory T cells

Dendritic cells (DC) have important functions in T cell immunity and T cell tolerance. Previously, it was believed that T cell unresponsiveness induced by immature DC (iDC) is caused by the absence of inflammatory signals in steady-state in vivo conditions and by the low expression levels of costimulatory molecules on iDC. However, a growing body of evidence now indicates that iDC can also actively maintain peripheral T cell tolerance by the induction and/or stimulation of regulatory T cell populations. In this study, we investigated the in vitro T cell stimulatory capacity of iDC and mature DC (mDC) and found that both DC types induced a significant increase in the number of transforming growth factor (TGF)-beta and interleukin (IL)-10 double-positive CD4(+) T cells within 1 week of autologous DC/T cell co-cultures. In iDC/T cell cultures, where antigen-specific T cell priming was significantly reduced as compared to mDC/T cell cultures, we demonstrated that the tolerogenic effect of iDC was mediated by soluble TGF-beta and IL-10 secreted by CD4(+)CD25(-)FOXP3(-) T cells. In addition, the suppressive capacity of CD4(+) T cells conditioned by iDC was transferable to already primed antigen-specific CD8(+) T cell cultures. In contrast, addition of CD4(+) T cells conditioned by mDC to primed antigen-specific CD8(+) T cells resulted in enhanced CD8(+) T cell responses, notwithstanding the presence of TGF-beta(+)/IL-10(+) T cells in the transferred fraction. In summary, we hypothesize that DC have an active role in inducing immunosuppressive cytokine-secreting regulatory T cells. We show that iDC-conditioned CD4(+) T cells are globally immunosuppressive, while mDC induce globally immunostimulatory CD4(+) T cells. Furthermore, TGF-beta(+)/IL-10(+) T cells are expanded by DC independent of their maturation status, but their suppressive function is dependent on immaturity of DC.

Acute myeloid leukaemia of mixed megakaryocytic and erythroid origin: a case report and review of the literature

We report the case of a 78-year-old man who presented with acute myeloid leukaemia showing subpopulations of cells expressing platelet-associated markers and the presence of a pan-myeloid component, besides glycophorin A-positive cells. Most of the immature cells had a proerythroblast-like morphology and we classified this case as an FAB-M6 variant, as suggested by Bain (1). According to the WHO classification, this leukaemia fulfilled the criteria of'AML with multilineage dysplasia' (2). Immunophenotyping characteristics showed two distinct aberrant subpopulations, a young pan-myeloid (CD45+ with low density, CD34+, CD117+, CD13+, CD33+, partial cytoplasmic myeloperoxidase (MPO)+) population with platelet-associated markers (CD41+, CD42+, CD61+) and a CD45+, CD117+, CD34- population with partial CD235a positivity indicative for erythroid maturation. This case belongs to the group of 'early' erythroblastic leukaemias where a subset of progenitor cells present with erythroid-megakaryocyte bipotentiality or are blocked at an early BFU-E (burst-forming unit erythrocyte)-like stage of erythroid differentiation (11, 12, 13).

Proinflammatory response of human leukemic cells to dsRNA transfection linked to activation of dendritic cells

Leukemic cells exert immunosuppressive effects that interfere with dendritic cell (DC) function and hamper effective antileukemic immune responses. Here, we sought to enhance the immunogenicity of leukemic cells by loading them with the double-stranded (ds) RNA Toll-like receptor 3 (TLR3) ligand polyriboinosinic polyribocytidylic acid (poly(I:C)), mimicking viral infection of the tumor cells. Given the responsiveness of DC to TLR ligands, we hypothesized that the uptake of poly(I:C)-loaded leukemic cells by immature DC (iDC) would lead to DC activation. Primary acute myeloid leukemia (AML) cells and AML cell lines markedly responded to poly(I:C) electroporation by apoptosis, upregulation of TLR3 expression, enhanced expression of major histocompatibility complex (MHC) and costimulatory molecules and by production of type I interferons (IFN). Upon phagocytosis of poly(I:C)-electroporated AML cells, DC maturation and activation were induced as judged by an increased expression of MHC and costimulatory molecules, production of proinflammatory cytokines and an increase of T helper 1 (T(H)1)-polarizing capacity. These immune effects were suboptimal when AML cells were passively pulsed with poly(I:C), indicating the superiority of poly(I:C) transfection over pulsing. Our results demonstrate that poly(I:C) electroporation is a promising strategy to increase the immunogenicity of AML cells and to convert iDC into activated mature DC following the phagocytosis of AML cells.

Expression analysis of immune-related genes in CD34+ progenitor-derived dendritic cells after exposure to the chemical contact allergen DNCB

We studied the changes in gene expression after exposure of human dendritic cells (DCs) to the model allergen dinitrochlorobenzene (DNCB). DCs were derived from CD34(+) progenitor cells of three different donors and exposed to 10 microM DNCB or solvent for several time intervals (3, 6 and 12h). cDNA microarrays were used to assess the transcriptional activity of 11,000 human genes. Compared to control gene expression, changes larger than +/-two-fold were observed for 241 genes after exposure to DNCB. Of these genes, 137 were up-regulated and 104 down-regulated. Twenty of these genes encode proteins that are related to the immune response (cytokines, chemokines, their receptors, cytokine/chemokines-related genes, transcription and signal transduction genes) and are discussed in more detail. Our data indicate that exposure to DNCB does not induce a typical maturation pattern in DCs.

Antigen-specific cellular immunotherapy of leukemia

Advances in cellular and molecular immunology have led to the characterization of leukemia-specific T-cell antigens and to the development of strategies for effective augmentation of T-cell immunity in leukemia patients. While several leukemia-related antigens have been identified, this review focuses on the Wilms' tumor 1 (WT1) antigen and the proteinase 3 (Pr3) antigen that are overexpressed in leukemic cells and are already being used in the clinical setting. Moreover, WT1 is also overexpressed in a vast number of nonhematological solid tumors, thereby expanding its use as a promising target for cancer vaccines. Examples of spontaneous immune responses against WT1 and Pr3 in leukemia patients are presented and the potential of WT1 and Pr3 for adoptive T-cell immunotherapy of leukemia is discussed. We also elaborate on the use of professional antigen-presenting cells loaded with mRNA encoding WT1 exploiting the advantage of broad HLA coverage for therapeutic vaccination purposes. Finally, the summarized data underscore the potential of WT1 for the manipulation of T-cell immunity in leukemia and in cancer in general, that will likely pave the way for the development of more effective and generic cancer vaccines.

Ex vivo induction of viral antigen-specific CD8 T cell responses using mRNA-electroporated CD40-activated B cells

Cell-based immunotherapy, in which antigen-loaded antigen-presenting cells (APC) are used to elicit T cell responses, has become part of the search for alternative cancer and infectious disease treatments. Here, we report on the feasibility of using mRNA-electroporated CD40-activated B cells (CD40-B cells) as alternative APC for the ex vivo induction of antigen-specific CD8(+) T cell responses. The potential of CD40-B cells as APC is reflected in their phenotypic analysis, showing a polyclonal, strongly activated B cell population with high expression of MHC and co-stimulatory molecules. Flow cytometric analysis of EGFP expression 24 h after EGFP mRNA-electroporation showed that CD40-B cells can be RNA transfected with high gene transfer efficiency. No difference in transfection efficiency or postelectroporation viability was observed between CD40-B cells and monocyte-derived dendritic cells (DC). Our first series of experiments show clearly that peptide-pulsed CD40-B cells are able to (re)activate both CD8+ and CD4(+) T cells against influenza and cytomegalovirus (CMV) antigens. To demonstrate the ability of viral antigen mRNA-electroporated CD40-B cells to induce virus-specific CD8+ T cell responses, these antigen-loaded cells were co-cultured in vitro with autologous peripheral blood mononuclear cells (PBMC) for 7 days followed by analysis of T cell antigen-specificity. These experiments show that CD40-B cells electroporated with influenza M1 mRNA or with CMV pp65 mRNA are able to activate antigen-specific interferon (IFN)-gamma-producing CD8(+) T cells. These findings demonstrate that mRNA-electroporated CD40-B cells can be used as alternative APC for the induction of antigen-specific (memory) CD8(+) T cell responses, which might overcome some of the drawbacks inherent to DC immunotherapy protocols.

Human herpesvirus-7 (HHV-7): current status

BACKGROUND

Human herpesvirus-7 (HHV-7) is a newly discovered virus and very little is known about its prevalence, biologic, immunologic and molecular biology aspect. Besides the HHV-7 etiologic role in a few cases of exanthem subitum, its association with other diseases has not been reported.

OBJECTIVES

To review what is currently known about HHV-7.

RESULTS

HHV-7 was first isolated in 1990 from purified T-cells from a healthy individual. Following this report, an independent isolation of HHV-7 was reported from the mononuclear cells (PBMC) of a chronic fatigue syndrome patient. HHV-7 is closely related to human herpesvirus-6 (HHV-6) and human cytomegalovirus (HCMV), but is distinct from Epstein-Barr virus (EBV), herpes simplex virus and varicella zoster virus. Using polyvalent and monoclonal antibodies, several HHV-7 viral proteins were identified, ranging from 136 to 30 kDa. HHV-7 infection occurs later than HHV-6, which appears in early childhood. HHV-7 is ubiquitous, and its prevalence rate is >85% in the US population, although its rates of prevalence in Japan is lower than in the USA and Europe. HHV-7 is frequently isolated from saliva; however, HHV-7 has been consistently isolated from PBMC from young children as well. Several cases of exanthem subitum have been linked to primary infection of HHV-7, suggesting that it may also cause exanthem subitum. Primary infection with HHV-7 was also reported from a patient with features of hepatitis and exanthem subitum. This virus was also isolated from tissues from a case of hepatosplenomegaly and pancytopenia lacking either EBV or HCMV. Thus far, no other disease associated with HHV-7 has been reported. Only one continuous T-cell line (SupT1) can support the replication of HHV-7, but the virus yield is extremely low.

CONCLUSIONS

It has been about 4 years since this member of the human herpesvirus family was reported. In the coming years, more data will be available on the epidemiology, biology, immunology, molecular biology, and pathogenesis of HHV-7. The finding of reciprocal interference between HHV-7 and HIV-1, suggesting competition at the receptor level is important, needs further work and here HHV-7 may play a role as a negative cofactor in the natural history of HIV infection. Because of HHV-7 interaction with HIV-1, the possibility of its vertical transmission needs to be investigated. This review on HHV-7 is intended to provide current information on HHV-7.

Messenger RNA electroporation is highly efficient in mouse embryonic stem cells: successful FLPe- and Cre-mediated recombination

Development of efficient short-term gene transfer technologies for embryonic stem (ES) cells is urgently needed for various existing and new ES cell-based research strategies. In this study, we present a highly efficient, nonviral non-DNA technology for genetic loading of mouse ES cells based on electroporation of defined mRNA. Here, we show that mouse ES cells can be efficiently loaded with mRNA encoding a green fluorescent reporter protein, resulting in a level of at least 90% of transgene expression without loss of cell viability and phenotype. To show that transgenes, introduced by mRNA electroporation, exert a specific cellular function in transfected cells, we electroporated stably transfected ES cell lines with mRNA encoding FLPe or Cre recombinase proteins in order to excise an FRT- or LoxP-flanked reporter gene. The results, as determined by the disappearance and/or appearance of a fluorescent reporter gene expression, show that FLPe and Cre recombinase proteins, introduced by mRNA electroporation, efficiently exert their function without influence on further culture of undifferentiated ES cell populations and their ability to differentiate towards a specific lineage.

Messenger RNA electroporation: an efficient tool in immunotherapy and stem cell research

Over the last decades medicine has developed tremendously, but still many diseases are incurable. The last years, cellular (gene) therapy has become a hot topic in biomedical research for the potential treatment of cancer, AIDS and diseases involving cell loss or degeneration. Here, we will focus on two major areas within cellular therapy, cellular immunotherapy and stem cell therapy, that could benefit from the introduction of neo-expressed genes through mRNA electroporation for basic research as well as for clinical applications. For cellular immunotherapy, we will provide a state-of-the-art on loading antigen-presenting cells with antigens in the mRNA format for manipulation of T cell immunity. In the area of stem cell research, we will highlight current gene transfer methods into adult and embryonic stem cells and discuss the use of mRNA electroporation for controlling guided differentiation of stem cells into specialized cell lineages.

RNA-based gene transfer for adult stem cells and T cells

Electroporation of mRNA has become an established method for gene transfer into dendritic cells for immunotherapeutic purposes. However, many more cell types and applications might benefit from an efficient mRNA-based gene transfer method. In this study, we investigated the potential of mRNA-based gene transfer to induce short-term transgene expression in adult stem cells and activated T cells, based on electroporation with mRNA encoding the enhanced green fluorescent protein. The results show efficient transgene expression in CD34-positive hematopoietic progenitor cells (35%), in in vitro cultured mesenchymal cells (90%) and in PHA-stimulated T cells (50%). Next to presentation of gene transfer results, potential applications of mRNA-based gene transfer in stem cells and T cells are discussed.

Current challenges in human embryonic stem cell research: directed differentiation and transplantation tolerance

Research towards potential curative transplantation of human embryonic stem (hES) cell-derived grafts in a variety of diseases has become an important topic since the successful derivation and propagation of hES cells from the inner cell mass of a blastocyst. However, clinical applicability can only be established after intensive laboratory studies that should elaborate on two major topics: A) the development of efficient, controlled and stable hES cell differentiation protocols for any specific cell type, and B) the induction of immunological tolerance against transplanted allogeneic hES cell-derived cell types. This review will briefly discuss: A) current possibilities in hES cell differentiation, followed by the development of viral, DNA and mRNA-based gene transfer strategies for hES cells, and B) possible immune modulation strategies for inducing immune tolerance against allogeneic hES cell transplants.

Cancer immunotherapy using RNA-loaded dendritic cells

Dendritic cells (DC) are the most professional antigen-presenting cells of the immune system and are capable of initiating immune responses in vitro and in vivo. One of the great challenges in immunotherapy protocols is to introduce relevant antigens into DC for stimulation of major histocompatibility complex (MHC) class I- and class II-restricted anti-tumour or anti-viral immunity. This review will focus on the development of mRNA-loaded DC-based immunotherapy vaccines. First, several published results concerning mRNA transfection efficiency in DC are compared. Next, an overview is given for several published studies describing CD8+ and CD4+ T-cell clone activation using RNA-loaded DC. These data show that RNA-loaded DC efficiently process and present antigenic epitopes. Next, published data from in vitro T-cell activation studies using RNA-loaded DC are summarized and provide evidence that RNA-loaded DC can efficiently stimulate in vitro primary and secondary immune responses. Finally, the summarized data provide evidence that RNA-loaded DC are a promising strategy for the development of future cancer vaccination strategies.

mRNA-electroporated mature dendritic cells retain transgene expression, phenotypical properties and stimulatory capacity after cryopreservation

Genetically modified dendritic cells (DC) are increasingly used in vitro to activate cytotoxic T lymphocyte (CTL) immune responses. Because T cell activation protocols consist of multiple restimulation cycles of peripheral blood lymphocytes with antigen-loaded mature DC, continuous generation of DC is needed throughout the experiment. Therefore, cryopreservation of DC loaded with antigen is a valuable alternative for weekly generation and modification of DC. Recently, we described an antigen loading method for DC based on electroporation of defined tumor antigen mRNA. In this study, we demonstrate that mRNA-electroporated DC can efficiently be prepared for cryopreservation. Using an optimized maturation and freezing protocol after mRNA electroporation, we obtained high transgene-expressing viable mature DC. In addition, we showed that these modified cryopreserved DC retain stimulatory capacity in an influenza model system. Therefore, cryopreservation of mature mRNA-electroporated DC is a useful method for continuous availability of antigen-loaded DC throughout T cell activation experiments.

Distal deep venous thrombosis in a hemophilia A patient with inhibitor and severe infectious disease, 18 days after recombinant activated factor VII transfusion

We describe a 38 year old hemophilia A patient with a factor VIII inhibitor who was admitted to our Hematology Department in January 2001 with a seriously infected and bleeding perianal ulcer. To treat infection and bleeding the patient received broad spectrum antibiotics and recombinant activated factor VII (rFVIIa) (Novoseven(R)) for about 1 month (see detailed time of administration and dosing schedule of rFVIIa further in text). Eighteen days after his last rVIIa infusion the patient developed an ultrasound proven right calf vein thrombosis. In the whole period of admission, preceding the thrombotic event the patient biologically showed a picture of severe systemic inflammatory disease as indicated by persistent increased levels of D-dimer and fibrinogen (table). It is an interesting point of discussion whether the calf thrombosis was provoked as a consequence of rFVIIa infusion (with symptoms 18 days after the last infusion) or as a consequence of long-standing immobilization and severe inflammatory disease immobilization and severe infection are conditions well known for promoting venous thromboembolic disease.

Antiproliferative effect of plant cytokinin analogues with an inhibitory activity on cyclin-dependent kinases

In this study, analogues of olomoucine, a previously described plant cytokinin analogue with cyclin-dependent kinase (CDK) inhibitory activity, were investigated for effect on CDK1 and CDK2 and for effect on cell proliferation. Eight new compounds exhibit stronger inhibitory activity on CDK1 and CDK2 and on cell proliferation than olomoucine. Some active compounds showed low inhibition of proliferation of normal myeloid growth. Improvement of inhibitory activity of known compounds with a C6-benzylamino group was brought about by substitution with one hydroxyl. Also, new C2 substituents associated with inhibitory activity on CDK and on cell proliferation are described. There was a significant correlation between effect on CDK and antiproliferative effect on the KG1 and Molt3 cell lines and on primary human lymphocytes, strongly suggesting that at least part of the antiproliferative effect of cytokinin analogues was due to inhibition of CDK activity. Cytokinin analogues induced apoptosis in a time- and concentration-dependent manner and changes in cell cycle distribution. The antiproliferative and pro-apoptotic effects of plant cytokinin analogues suggest that they are a new class of cytostatic agents and that they may find an application in the chemotherapy of cancer.

Reduction of visible bone metastases by clodronate therapy in breast cancer

The current report describes a 57-year-old patient with multiple bone metastases 14 years after her initial treatment for breast cancer. The only therapy the patient received for her osteolytic lesions was oral clodronate (800 mg/daily), as she refused any other kind of treatment. On bone scintigraphy the number of visible bone metastases diminished slowly and after two years only a few minor lesions could be seen. Together with this report the value of oral clodronate as anti-osteolytic therapy in breast cancer patients is discussed.

Development of reverse transcriptase PCR assays for detection of active human herpesvirus 6 infection

We developed reverse transcriptase (RT) PCR assays for the detection of mRNA from three spliced genes of human herpesvirus 6 (HHV-6), the immediate-early genes U16/U17 and U89/U90 and the late gene U60/U66. Sequence analysis determined the splicing sites of these genes. The new assays may be instrumental in investigating the association between HHV-6 and disease.

Highly efficient gene delivery by mRNA electroporation in human hematopoietic cells: superiority to lipofection and passive pulsing of mRNA and to electroporation of plasmid cDNA for tumor antigen loading of dendritic cells

Designing effective strategies to load human dendritic cells (DCs) with tumor antigens is a challenging approach for DC-based tumor vaccines. Here, a cytoplasmic expression system based on mRNA electroporation to efficiently introduce tumor antigens into DCs is described. Preliminary experiments in K562 cells using an enhanced green fluorescent protein (EGFP) reporter gene revealed that mRNA electroporation as compared with plasmid DNA electroporation showed a markedly improved transfection efficiency (89% versus 40% EGFP(+) cells, respectively) and induced a strikingly lower cell toxicity (15% death rate with mRNA versus 51% with plasmid DNA). Next, mRNA electroporation was applied for nonviral transfection of different types of human DCs, including monocyte-derived DCs (Mo-DCs), CD34(+) progenitor-derived DCs (34-DCs) and Langerhans cells (34-LCs). High-level transgene expression by mRNA electroporation was obtained in more than 50% of all DC types. mRNA-electroporated DCs retained their phenotype and maturational potential. Importantly, DCs electroporated with mRNA-encoding Melan-A strongly activated a Melan-A-specific cytotoxic T lymphocyte (CTL) clone in an HLA-restricted manner and were superior to mRNA-lipofected or -pulsed DCs. Optimal stimulation of the CTL occurred when Mo-DCs underwent maturation following mRNA transfection. Strikingly, a nonspecific stimulation of CTL was observed when DCs were transfected with plasmid DNA. The data clearly demonstrate that Mo-DCs electroporated with mRNA efficiently present functional antigenic peptides to cytotoxic T cells. Therefore, electroporation of mRNA-encoding tumor antigens is a powerful technique to charge human dendritic cells with tumor antigens and could serve applications in future DC-based tumor vaccines.

Gene therapy: principles and applications to hematopoietic cells

Ever since the development of technology allowing the transfer of new genes into eukaryotic cells, the hematopoietic system has been an obvious and desirable target for gene therapy. The last 10 years have witnessed an explosion of interest in this approach to treat human disease, both inherited and acquired, with the initiation of multiple clinical protocols. All gene therapy strategies have two essential technical requirements. These are: (1) the efficient introduction of the relevant genetic material into the target cell and (2) the expression of the transgene at therapeutic levels. Conceptual and technical hurdles involved with these requirements are still the objects of active research. To date, the most widely used and best understood vectors for gene transfer in hematopoietic cells are derived from retroviruses, although they suffer from several limitations. However, as gene transfer mechanisms become more efficient and long-term gene expression is enhanced, the variety of diseases that can be tackled by gene therapy will continue to expand. However, until the problem of delivery and subsequent expression is adequately resolved, gene therapy will not realize its full potential. The first part of this review gives an overview of the gene delivery technology available at present to transfer genetic sequences in human somatic cells. The relevance of the hematopoietic system to the development of gene therapy strategies as well as hematopoietic cell-based gene therapy is discussed in the second part.

Gene-based cancer vaccines: an ex vivo approach

The application of gene transfer techniques to immunotherapy has animated the field of gene-based cancer vaccine research. Gene transfer strategies were developed to bring about active immunization against tumor-associated antigens (TAA) through gene transfer technology. A wide variety of viral and nonviral gene transfer methods have been investigated for immunotherapeutic purposes. Ex vivo strategies include gene delivery into tumor cells and into cellular components of the immune system, including cytotoxic T cells and dendritic cells (DC). The nature of the transferred genetic material as well as the gene transfer method has varied widely depending on the application. Several of these approaches have already been translated into clinical gene therapy trials. In this review, we will focus on the rationale and types of ex vivo gene-based immunotherapy of cancer. Critical areas for future development of gene-based cancer vaccines are addressed, with particular emphasis on use of DC and on the danger-tolerance hypothesis. Finally, the use of gene-modified DC for tumor vaccination and its prospects are discussed.

Identification of envelope glycoproteins H and B homologues of human herpesvirus 7

The genes encoding the envelope glycoprotein H (gH) and gB homologues were identified by sequencing genomic clones of human herpesvirus-7 (HHV-7), strain JI. A gB cDNA clone from HHV-7 strain AL was also identified. The deduced primary translation products of the gH and gB genes are a protein of 690 amino acids, with a predicted mass of 80.4 kD, and a protein of 822 amino acids, with a predicted mass of 93.3 kD, respectively. Both the predicted proteins have the characteristics of transmembrane glycoproteins, containing signal and transmembrane sequence motifs and characterized by the presence of 10 (gH) and 11 (gB) potential motifs for N-glycosylation. Comparison of amino acid sequence of HHV-7 gH and gB with the homologous sequences of the other human herpesviruses reveals closest homology with HHV-6 (38.8% identity for gH, 56.2% identity for the gB). In addition, significant sequence similarity was also observed between the gH and gB of HHV-7 and the homologs encoded by human cytomegalovirus (21.6% identity for gH, 37.6% identity for gB). No significant differences existed between the gB sequence of the two different HHV-7 strains analyzed. The products of the HHV-7 gH and gB expressed transiently in eukaryotic cells were specifically recognized by an HHV-7-reactive human serum in immunofluorescence assays.

Establishment of serum-free pre-colony forming unit assays for differentiation of primitive hematopoietic progenitors: serum induces early macrophage differentiation and inhibits early erythroid differentiation of CD34++CD38- cells

In this report we show that serum has differentiation-inducing effects on primitive hematopoietic progenitor cells with the CD34++CD38- immunophenotype. Using the pre-colony forming unit (pre-CFU) assay as a model for early myelopoiesis, we compared the effects of serum-containing and serum-free media and evaluated different cytokine cocktails [interleukin (IL)-1, IL-3, IL-6, kit ligand with and without the Flt3/Flk2 ligand (FL)]. In this assay, pre-CFUs are defined as cells unable to form colonies when plated directly in semi-solid assays, but which can differentiate into CFUs when cultured in liquid medium containing early-acting cytokines. In one of the investigated serum-free media, the average myeloid expansion in liquid medium reached up to more than 50% of that obtained in serum-containing medium. In addition, our experiments revealed differences in the clonogenic output between cells cultured in serum-free medium and those cultured in serum-containing medium, demonstrating that serum has a monocyte differentiation-inducing effect on primitive hematopoietic progenitors. Also in serum-free medium, higher proportions of erythroid progenitors were generated. These differentiation-inducing effects of serum further emphasize the need for serum-free culture protocols for hematopoietic graft engineering. Addition of FL to the culture media ameliorated cellular expansion and resulted in a decrease in the proportion of erythroid and granulocyte progenitors and an increase in the proportion of monocyte progenitors. In conclusion, this study shows that good serum-free conditions are available for differentiation assays with primitive hematopoietic progenitors and demonstrates that serum and FL have biasing effects on the initial phase of hematopoietic differentiation, favoring the monocyte lineage.

GP130 and c-kit signalling, initiated by the sIL-6R/IL-6 complex, is insufficient to expand the primitive adult bone marrow CD34+CD38- pre-CFU cell

It has previously been shown that gp130 and c-kit signalling synergize for the ex vivo expansion of human cord blood (CB) CD34+ haematopoietic progenitor cells. We were interested in evaluating this synergy within an ontogenetically different haematopoietic tissue [i.e. adult bone marrow (BM)] and on a more primitive progenitor subset (i.e. CD34+ CD38-cells), which are highly enriched for pre-colony forming unit (CFU) cells. These cells were plated out in a primary liquid culture supplemented with either interleukin (IL)-6+stem cell factor (SCF), IL-6+ SCF+soluble IL-6 receptor (sIL-6R), IL-6+SCF+sIL-6R+IL3+IL-1 or SCF+IL-3+IL-6+IL-1. Cell counting after liquid culture revealed an absolute expansion of 2.2-, 4.1-, 89.5- and 65.7-fold compared with initial cell input for the four-cytokine combinations, respectively. The secondary read-out assay revealed that this cell expansion in the liquid culture also resulted in CFU generation, with absolute cloning efficiencies of 0.002, 0.024, 12.13 and 7.73 (per cell initially present) for the respective cytokine combinations. These results indicate that gp130 and c-kit signalling alone (i.e. using IL6+SCF+sIL-6R), in terms of both cell number and CFU generation, insufficiently stimulate primitive adult BM CD34+CD38- haematopoietic cells in order to reach a CFU generation comparable with that obtained after multifactor stimulation. Adding sIL-6R to the multifactor stimulation and compared with this multifactor stimulation, a 1.7-fold synergy in terms of cell expansion and a 3.0-fold synergy in terms of CFU generation are obtained. The sIL-6R/IL-6 complex thus has a narrower spectrum of action on primitive adult BM CD34+CD38- cells than on CB CD34+ cells.

Comparison between capillary and nano liquid chromatography-electrospray mass spectrometry for the analysis of minor DNA-melphalan adducts

Nano liquid chromatography (nanoLC) coupled to electrospray mass spectrometry (ES-MS) was evaluated for the analysis of DNA adducts in melphalan-treated Jurkat cells. The detection limit of the nanoLC-ES-MS-MS system was assessed using a dAMP-melphalan adduct. Compared to capillary liquid chromatography (capLC) ES-MS the absolute detection limit could be improved by a factor 10, leading to the detection of 395 fg dAMP-melphalan adduct under single-ion monitoring conditions at a S/N of 14. Minor adducts such as cross-linked adducts could be detected in in vitro solutions of 2'-deoxynucleotides (dNMP) treated with melphalan using column-switching nanoLC-ES-MS. These adducts were not found using capLC-ES-MS. More detailed structural information of the alkylation sites was obtained by examining the nanoLC-ES-MS-MS data. Jurkat cells were treated with melphalan, the modified DNA was isolated and enzymatically hydrolyzed. Several modified dinucleotides were identified, the most abundant adducts were pdG(Mel(Cl))pdC (m/z=453, t(r)=17.0 min) and pdG(Mel(OH)) pdC ring opened (m/z=453, t(r)=39.5 min).

Efficient generation of stably electrotransfected human hematopoietic cell lines without drug selection by consecutive FACsorting

BACKGROUND

Current methods to establish stably transfected cell lines by nonviral techniques involve coselection for a drug selection marker. However, this approach suffers from several drawbacks. We developed a fluorescence-activated cell sorting (FACS)-based protocol for the selection and isolation of stable hematopoietic electrotransfectants without the need for selective growth conditions.

METHODS

Leukemic K562 cells were electroporated with the enhanced green fluorescent protein (EGFP) reporter gene and FACsorted to obtain stably EGFP-expressing cells. Stable EGFP(+) clones were established by single-cell sorting.

RESULTS

Efficiency of stable EGFP gene expression increased steadily in function of number of consecutive FACsorts. Stable transfectants (>99% EGFP(+)) were obtained after four FACsorts. Furthermore, several single-cell derived clones with variable levels of stable EGFP expression were isolated and cultured without the use of selective growth media.

CONCLUSIONS

EGFP is an effective selection marker for the generation and isolation of stably transfected hematopoietic cell clones without the need for selection in toxic media that could create a potentially undesirable stress environment for stably transfected cells.

High-level transgene expression in primary human T lymphocytes and adult bone marrow CD34+ cells via electroporation-mediated gene delivery

The design of effective gene delivery systems for gene transfer in primary human blood cells is important both for fundamental hematopoiesis research and for cancer gene therapy strategies. Here, we evaluated electroporation as a nonviral means for transfection of activated human T lymphocytes and adult bone marrow (BM) CD34+ cells. We describe optimal culture and electroporation parameters for efficient gene delivery in prestimulated T lymphocytes (16.3 +/-1.3%), as well as 2-day cultured adult BM CD34+ cells (29.6+/-4.6%). PHA-stimulated T cells were most receptive for transfection after 48h of in vitro culture, while T cells stimulated by CD3 cross-linking and interleukin (IL)-2 achieved maximum transfection levels after 72 h of prestimulation. Kinetic analysis of EGFP expression revealed that activated T lymphocytes maintained transgene expression at high levels for a prolonged period. In addition, fresh unstimulated BM CD34+ cells were consistently transfected (5.2+/-0.4%) with minimal cytotoxicity (<5%), even without preliminary CD34+ cell purification. Both T cells and CD34+ cells retained their phenotype and functional capacity after electroporation. These results demonstrate that electroporation is a suitable nonviral transfection technique that may serve applications in gene therapy protocols using T lymphocytes or CD34+ cells.

Generation of T cells from adult human hematopoietic stem cells and progenitors in a fetal thymic organ culture system: stimulation by tumor necrosis factor-alpha

To investigate the T-lymphopoietic capacity of human adult bone marrow (ABM) hematopoietic progenitor cells, CD34+Lin-, CD34+CD38+, and CD34++CD38- cells were cultured in a severe combined immunodeficient (SCID) mouse fetal thymic organ culture (FTOC). Direct seeding of these progenitors resulted in a moderate to severe cell loss, particularly for the CD34++CD38- cell fraction, and T cells could only be generated from the CD34+Lin- fraction. Preincubation for 36 hours with interleukin-3 (IL-3) and stem cell factor (SCF) led to an improved cell survival and proliferation, although T-cell development was seen only in the CD34+Lin- fraction. Addition of tumor necrosis factor (TNF)-alpha to IL-3 + SCF-supplemented preincubation medium resulted in optimal cell survival, cell proliferation. and T-cell generation of all 3 cell fractions. The TNF-alpha effect resulted in an up-regulation of CD127 (ie, the IL-7 receptor alpha-chain) in a small subset of the CD34+ cells. No evidence could be generated to support the possibility that TNF-alpha inhibits a cell population that suppresses T-cell differentiation. A quantitatively different T-cell generation potency was still seen between the 3 subpopulations: CD34+Lin- (100% success rate) > CD34+CD38+ (66%) > CD34++CD38- (25%). These data contrast with our previous findings using fetal liver and cord blood progenitors, which readily differentiate into T-lymphocytes in FTOC, even without prestimulation with cytokines. Our results demonstrate that adult CD34++CD38- cells, known to contain hematopoietic stem cells, can differentiate into T-lymphocytes and that a significant difference exists in T-lymphopoietic activity of stem cells derived from ontogenetically different sources. (Blood. 2000;95:2806-2812)

Platelet prothrombinase activity, a final pathway platelet procoagulant activity, is overexpressed in type 1 diabetes: no relationship with mean platelet volume or background retinopathy

There is overwhelming evidence that platelets from diabetic individuals are hyperreactive, not only when microvascular complications are apparent, but already at an early stage of the disease. There is still controversy about the question of whether primary hyperreactive platelets may contribute to the origin or progression of microangiopathy or whether diabetic platelet hyperfunctionality is just a logical consequence of a continuous low-grade activation of platelets by contact with a diseased microvascular wall. As a consequence of platelet activation, the outer layer of its phospholipid membrane is more procoagulant than in the quiescent state, stimulating thrombin formation in plasma. This platelet function is called platelet procoagulant activity. We studied platelet prothrombinase activity (PPA), a final pathway platelet procoagulant activity of type 1 diabetic platelets, and looked for an eventual correlation with microvascular disease (background retinopathy) and mean platelet volume (MPV). Stypven clotting times (SCTs), reflecting PPA expression, and MPV of citrated platelet-rich plasma (PRP), were measured in 21 patients with type 1 diabetes-10 with and 11 without background retinopathy-under clinically acceptable metabolic control and compared them to 20 disease-free voluntary controls. We also compared PPA expression and MPV in diabetic individuals with and without retinopathy. With the SCT, a selective test adapted for studying PPA in PRP, we found hyperexpression of PPA in all diabetic patients. We found no difference in MPV between diabetic and control PRP. Comparing patients with and without background retinopathy we found no significant difference in PPA expression. From these results, we suggest that the phospholipid surface of diabetic platelets, more than the surface of normal control platelets, stimulate the expression of PPA. This diabetic platelet coagulant anomaly was not related to an increased platelet mass (higher MPV) nor to the presence of microangiopathy. We conclude that PPA hyperexpression is associated with patients with type 1 diabetes, already occurring in an early stage of the disease, and not necessarily a consequence of early-stage microvascular disease, because the anomaly is also demonstrable, in the same degree, in patients with diabetes without microangiopathy.

The platelet function analyzer (PFA-100) may not be suitable for monitoring the therapeutic efficiency of von willebrand concentrate in type III von willebrand disease

We describe a type-III von Willebrand patient who was admitted to the hospital with severe deformity and functional deficit of the left knee joint due to recurrent hemarthrosis. Orthopedic intervention was necessary. To prevent bleeding episodes, von Willebrand factor (vWF) replacement therapy was given during and after surgery. APTT, plasma FVIII activity (FVIIIc), vWF antigen (vWF Ag), and vWF ristocetin cofactor (vWF Rco) were measured. Primary hemostasis was monitored using the PFA-100. This "Platelet Function Analyzer" is designed to measure platelet adhesion and aggregation capacities. Whole blood is aspirated through a capillary and is forced to flow through the central hole of a membrane coated with collagen and epinephrine (COL/EPI) or ADP (COL/ADP) as platelet activators. Irreversible platelet aggregation results in the formation of a stable platelet plug, closing the central hole. The result is expressed as "closure time" (CT), i.e., time necessary to stop the blood flow, and is a measure of platelet hemostasis capacity. Laboratory investigations during substitution therapy revealed no shortening of closure times with both COL/EPI and COL/ADP cartridges despite normalization of plasma vWF Ag, vWF Rco, and FVIIIc levels. These observations suggest that intraplatelet vWF, which is totally absent in type-III von Willebrand disease, plays an important function in the adhesion of platelets to the collagen-coated membrane of the PFA-100 system, simulating an injured vessel wall. Consequently, we conclude that the PFA-100 may not be suitable for monitoring the therapeutic efficacy of von Willebrand concentrate in type-III von Willebrand patients during substitution therapy.

Developmentally regulated responsiveness to transforming growth factor-beta is correlated with functional differences between human adult and fetal primitive hematopoietic progenitor cells

Important functional differences exist between primitive CD34++ CD38- hematopoietic progenitor cells derived from human fetal liver (FL) and adult bone marrow (ABM). FL progenitors are known to have higher proliferative capacities and lower cytokine requirements than their ABM counterparts. In this study, we isolated FL and ABM CD34++ CD38- cells and used a two-stage culture system to investigate the effects of transforming growth factor-beta (TGF-beta) and blocking anti-TGF-beta antibodies (anti-TGF-beta) on these cells. First, we demonstrate that FL progenitors are significantly less sensitive to the inhibitory effects of TGF-beta than ABM cells. Second, whereas ABM cells are significantly stimulated by anti-TGF-beta, only very limited effects are seen on FL cells. Third, we show that the effect of anti-TGF-beta is mainly situated at the level of the initial cell cycles of very primitive progenitor cells with a high proliferation potential. Fourth, we demonstrate that blocking the effects of endogenous TGF-beta reduces the growth factor requirements of ABM cells in order to proliferate and differentiate. Based on these data, we hypothesize that at least part of the functional differences that exist between adult and fetal stem cells can be accounted for by a developmental different responsiveness to TGF-beta.

The evolution of platelet procoagulant activity of remnant platelets in stored platelet concentrates prepared by the platelet-rich plasma method and the buffy coat method

Platelets stored as concentrates are gradually activated (storage lesion), a process associated with changes in the expression of platelet procoagulant activity (PPCA). The aim of the present study was to evaluate the evolution of PPCA and the mean platelet volume (MPV) of stored platelets prepared according to the platelet-rich method (PRM) and the buffy coat method (BCM). Using the platelet factor 3 availability clotting test (PF3AT) on appropriately diluted concentrate samples, we found a decrease in PPCA expression of remnant platelets as a function of storage time (0.025 < p < 0.01 between day 1 and 7) in PRM-derived but not in BCM-derived platelet concentrates. Using the PF3AT reduction test we found a more important clotting time reduction in samples obtained from BCM than in samples obtained from PRM platelet concentrates, suggesting a higher PPCA expression of BCM platelets, not significant after 1 day but highly significant after 3 days (p < 0.0005) and after 7 days (p < 0.0005) of storage, as compared with PRM platelets. For both PRM and BCM concentrates there were no significant MPV changes as a function of storage time, but at any storage day the MPV of BCM concentrates was significantly higher (p < 0.0005) than the MPV of PRM concentrates. We conclude that the decrease of PPCA expression in PRM-derived concentrates as a function of storage time is in agreement with the gradual decrease of the platelet activation status in PRM concentrates during storage. There are probably several factors or variables causing platelets of BCM concentrates to express higher PPCA than those of PRM concentrates. Higher PPCA expression in BCM concentrates may be explained by an intrinsic platelet property, such as a difference in MPV between the two kinds of concentrates, or it may be related to an extrinsic factor such as different storage media, e.g., undiluted autologous plasma in PRM concentrates versus Plasmalyte A-diluted autologous plasma in BCM concentrates. Whether the difference in PPCA expression of remnant platelets in PRM and BCM concentrates is just an in vitro laboratory finding or may have consequences for the therapeutic efficiency of the concentrates is an interesting, still unresolved question.

Absence of a directly causative role for human herpesvirus 7 in human lymphoma and a review of human herpesvirus 6 in human malignancy

In search of a (new) viral etiological agent, we screened 64 lymph node samples from Hodgkin's disease (HD) and 43 samples (32 lymph node and 11 skin biopsies) from non-Hodgkin's lymphoma (NHL) for human herpesvirus 7 (HHV-7). Twenty-nine control samples were tested as well, including 17 with benign lymphadenopathy. None of the samples tested positive by Southern blot hybridization using HHV-7-specific probes. We conclude that there is no major HHV-7 load in human lymphoma and that HHV-7 is not likely to be directly involved in its etiology. This is in contrast to a small minority of human lymphoproliferative diseases in which HHV-6 can be found at high copy number, but in which an etiological role is still uncertain.

Decreasing antibiotic resistance of Enterobacteriaceae by introducing a new antibiotic combination therapy for neutropenic fever patients

Prompt empiric antibiotic therapy is of critical importance for patients with neutropenic fever. However, a major concern with important clinical consequences is the emergence of bacterial resistance to antibiotics. After using ceftazidime with a glycopeptide as initial empiric therapy for neutropenic fever, we were confronted with a 75% reduced susceptibility rate to ceftazidime of inducible Enterobacteriaceae collected in 1994. The initial empiric therapy was therefore replaced in May 1995 by a combination of cefepime with amikacin, with addition of a glycopeptide after 48 h if necessary. After this change, we observed a significant decrease in reduced susceptibility of inducible Enterobacteriaceae, not only to ceftazidime, but also to amikacin, cotrimoxazole and ciprofloxacin. There was also a decrease in reduced susceptibility of non-inducible Enterobacteriaceae, such as Klebsiella spp, to ceftazidime. The reduction of resistance may be related at least in part to the combined use of cefepime together with an aminoglycoside. This study shows that it is possible to reverse bacterial resistance by modifying the antibiotic regimen used.

CD34++ CD38- and CD34+ CD38+ human hematopoietic progenitors from fetal liver, cord blood, and adult bone marrow respond differently to hematopoietic cytokines depending on the ontogenic source

CD34++ CD38- and CD34+ CD38+ hematopoietic progenitor cells (HPCs) from human fetal liver (FL), cord blood (CB), and adult bone marrow (ABM) were isolated and investigated for their growth characteristics, cytokine requirements and response to two modulators of early hematopoiesis, interferon (IFN)-gamma and macrophage inflammatory protein (MIP)-1alpha. We observed first that a significantly lower percentage of CD34++ cells were CD38- in ABM than in FL and CB. Second, the functional differences between CD34++ CD38- and CD34+ CD38+ cells were less pronounced in FL and CB than in their ABM counterparts. Third, an inverse correlation was found between growth factor response and the ontogenic age of HPCs, and a direct correlation was noted between cytokine requirements and the ontogenic age of HPCs. Fourth, spontaneous colony formation in a classic semisolid culture system was reproducibly obtained only in the ontogenically earliest cells, that is, in FL but not in CB and ABM, in which no such spontaneous colony formation was observed. Fifth, the modulatory effects of IFN-gamma and MIP-1alpha were qualitatively different depending on the ontogenic age of the progenitor source: whereas IFN-gamma was only a selective inhibitor of primitive CD34++ CD38- ABM progenitor cells, it inhibited both CD34++ CD38- and CD34+ CD38+ FL and CB cells to the same extent. In contrast to the effects of MIP-1alpha on ABM, we could not find any consistently stimulatory or inhibitory effects on FL and CB progenitors. In conclusion, important functional and biologic differences exist between FL, CB, and ABM progenitor cells, and these differences could have major implications for the use of these cell populations in preparative protocols of ex vivo expansion, transplantation strategies, or gene transfer experiments.