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The sperm chromatin structure assay (SCSA) has been proposed as a useful addition to the battery of tests routinely used to explore semen quality and hence to give an indication of the likelihood of a successful pregnancy. As usually performed at present, the assay yields two main sperm variables, the DNA fragmentation index (DFI) and the high DNA stainability (HDS). In the present study 275 patients undergoing 215 in vitro fertilization (IVF) and 215 intracytoplasmic sperm injection (ICSI) cycles were studied with the purpose of defining the clinical significance of HDS in IVF and ICSI cycles. Using the Spearman correlation test there were no significant statistical relationships between %HDS and fertilization rate, rate of embryo growth, blastocyst rate, implantation rate, or live birth rate. Rate of pregnancy loss showed a negative relationship significant at the 0.05 level which is unexplained. It is not known whether the normal practice of using processed sperm for fertilization plays any part in this lack of a negative effect of HDS level upon the stages of the cycle. A total of 16 patients with HDS levels >28% had an average live birth rate of 47.8% and an average pregnancy loss of 8.7%, which compared favourably with the group of patients as a whole.

Deep photoacoustic imaging of mammalian cells featuring genetically encoded contrast is reported.

Somatic mutations within noncoding genomic regions that aberrantly activate oncogenes have remained poorly characterized. Here we describe recurrent activating intronic mutations of LMO2, a prominent oncogene in T-cell acute lymphoblastic leukemia (T-ALL). Heterozygous mutations were identified in PF-382 and DU.528 T-ALL cell lines in addition to 3.7% of pediatric (6 of 160) and 5.5% of adult (9 of 163) T-ALL patient samples. The majority of indels harbor putative de novo MYB, ETS1, or RUNX1 consensus binding sites. Analysis of 5′-capped RNA transcripts in mutant cell lines identified the usage of an intermediate promoter site, with consequential monoallelic LMO2 overexpression. CRISPR/Cas9-mediated disruption of the mutant allele in PF-382 cells markedly downregulated LMO2 expression, establishing clear causality between the mutation and oncogene dysregulation. Furthermore, the spectrum of CRISPR/Cas9-derived mutations provides important insights into the interconnected contributions of functional transcription factor binding. Finally, these mutations occur in the same intron as retroviral integration sites in gene therapy–induced T-ALL, suggesting that such events occur at preferential sites in the noncoding genome., National Institute for Health Research (Great Britain). Biomedical Research Centre, Hope Funds for Cancer Research Grillo-Marxuach Family Fellow

We visualized insulin uptake in vivo across the apical membrane of the rat proximal tubule (PT) by confocal microscopy; we compared it with in vitro findings in a rat PT cell line (WKPT) using fluorescence microscopy and flow cytometry. Surface tubules were observed in vivo with a 633-nm single laser-illuminated real-time video-rate confocal scanning microscope in upright configuration for optical sectioning below the renal capsule. Fields were selected containing proximal and distal tubules; Cy5-labeled insulin was injected twice (the second time after ∼140 min) into the right jugular vein, and the fluorescence signal (at 650-670 nm) was recorded. Fluorescence was detected almost immediately at the brush-border membrane (BBM) of PT cells only, moving inside cells within 30-40 min. As a measure of insulin uptake, the ratio of the fluorescence signal after the second injection to the first doubled (ratio: 2.11 ± 0.26, mean ± SE, n = 10), indicating a "priming," or stimulating, effect of insulin on its uptake mechanism at the BBM. This effect did not occur after pretreatment with intravenous lysine (ratio: 1.03 ± 0.07, n = 6; P < 0.01). Cy2-or Cy3-labeled insulin uptake in a PT cell line in vitro was monitored by 488-nm excitation fluorescence microscopy using an inverted microscope. Insulin localized toward the apical membrane of these cells. Semiquantitative analysis of insulin uptake by flow cytometry also demonstrated a priming effect (upregulation) on insulin internalization in the presence of increasing amounts of insulin, as was observed in vivo; moreover, this effect was not seen with, or affected by, the similarly endocytosed ligand β2-glycoprotein. Copyright © 2009 the American Physiological Society.

Levels of circulating red blood cell (RBC)-derived vesicles are increased in sickle cell anaemia (SCA) and thalassaemia intermedia (TI) but the mechanisms, effects and controlling factors may differ. This study found that levels of vesicles and intravascular haemolysis were linked as shown by the correlation between levels of vesicles and plasma Hb. Vesicle levels were 6-fold greater in SCA and 4-fold greater in TI than in controls. The proportion of plasma Hb within vesicles was increased in SCA and TI with a significantly higher proportion in TI. We examined whether subpopulations of RBC expressing phosphatidylserine (PS) were a source of PS(+) vesicles and observed a significant association. Thrombin generation was promoted by the vesicles in which 40-50% expressed PS. In TI, markers of thrombin generation were significantly related to PS(+) RBC. Splenectomy in TI had significant effects including greater increases in vesicle levels, plasma Hb, PS(+) RBCs and thrombin generation markers than in unsplenectomised patients. In hydroxycarbamide (HC)-treated SCA patients these measures were decreased compared with untreated controls. The relationship between vesicle levels and plasma Hb suggests a mechanism linking vesiculation to haemolysis and consequently nitric oxide (NO) bioavailability and suggests a means by which HC treatment improves NO bioavailability.

Summary. Background: Cellular prion protein (PrPC) is a naturally occurring protein in normal individuals which adopts an abnormal conformation, termed scrapie prion protein (PrPSc) that is associated with disease. There is great concern that clinically asymptomatic variant Creutzfeldt–Jacob disease (vCJD) may transmit PrPSc in blood transfusion products. PrPC is widely expressed and has been found in human blood. The majority of cellular borne PrPC is associated with platelets (84%). Although PrPC mRNA has been demonstrated in platelets, the quantity is unknown and may not reflect the total PrPC present. Objective: To investigate the expression of PrPC in the megakaryocyte lineage. Methods: The expression of PrPC was studied in CD34+ cells, cultured megakaryocytes and platelets using electron microscopy, flow cytometry, semi-quantitative RT-PCR and immunofluorescence confocal microscopy. Results and conclusions: The expression of PrPC appeared to increase with differentiation and polyploidization in the megakaryocyte lineage. PrPC was located within platelet α-granules and its source is likely to be from megakaryocyte precursors. If PrPSc has a similar distribution, these results have implications for the selection of blood donors and preparation of cell-depleted blood products.

This report concerns congenitally Na(+)-K(+) leaky red cells of the 'hereditary stomatocytosis' class. Three new isolated cases and one new pedigree are described, and one previously reported case is expanded. In all cases, Western blotting of red cell membranes revealed a deficiency in the 32 kDa membrane protein, stomatin. All showed pronounced cation leaks at 37 degrees C with markedly abnormal intracellular Na(+) and K(+) concentrations, like all other such stomatin-deficient cases. Consistent with recent findings in two previously described British pedigrees, immunocytochemistry demonstrated that the deficiency of stomatin was not complete. On typical blood films, some red cells showed positive stomatin immunoreactivity, while most were negative, although in one case only a minority were negative. All platelets and neutrophils were stomatin positive. The cases differed markedly between themselves with regard to the temperature dependence of the passive leak to K(+). Three showed a simple monotonic temperature dependence, while two showed a minimum at around 20-25 degrees C, such that the cells were extremely leaky at 0 degrees C, giving the phenotype known as 'cryohydrocytosis'. These patients are the only two known cases of stomatin-deficient cryohydrocytosis. Both showed a congenital syndrome of mental retardation, seizures, cataracts and massive hepatosplenomegaly, probably defining a new haemato-neurological syndrome.

Summary. The migration of haemopoietic stem and progenitor cells across endothelium lining bone marrow sinuses is a critical first step in the homing and successful engraftment of these cells. We have previously shown that freshly isolated mobilized peripheral blood CD34+ cells adhere to the endothelial surface but do not transmigrate unless activated by growth factors. The aim of this work was to examine the relationship between cell cycle progression, cell division and migration across endothelium. We now show that the enhanced migration of cytokine-activated cells is selective for cells which are in G0G1 phase of the cell cycle. Thus, the transmigrated population of CD34+ cells was enriched for cells in G0G1 phase, and sorted cells in G0G1 migrated more efficiently than those in S+G2M. Conversely, cells in S+G2M were more adherent to endothelium, a finding that may explain their reduced migration. Using the cytoplasmic dye, carboxyfluorescein diacetate succinimidyl ester, to track the divisional kinetics of CD34+ cells, we found that migration occurred preferentially in non-divided cells. Thus, although CD34+ cells require cytokine activation in order to migrate, cell division is not required for transmigration, which occurs optimally before cells enter S phase. The superior migratory ability of CD34+ cells in G0G1 phase of the cell cycle may have important implications for the homing and engraftment of ex vivo expanded cells.

To date, constitutively activating point mutations reported in hematopoietic growth factor receptors in patients with acute myeloid leukemia (AML) have been restricted to receptors with intrinsic tyrosine kinase activity such as c-kit and FLT3. We describe here a Thr617Asn mutation in the transmembrane domain of the non-tyrosine kinase receptor for granulocyte colony-stimulating factor (G-CSF) in the blast cells of two out of 555 AML patients examined. The mutant receptor conferred growth factor independence on factor-dependent Ba/F3 cells. In the absence of ligand, immunoblotting showed weak phosphorylation of JAK2, STAT3, ERKs 1 and 2 and the receptor itself, and there was approximately 70% of maximal growth in a proliferation assay. All signals were significantly enhanced in the presence of G-CSF. Retroviral transduction of mutant receptor into primary hematopoietic CD34+ cells induced G-CSF independent myeloid differentiation as assessed by the development of neutrophils and surface expression of CD11b and CD14. These results confirm the importance of the transmembrane domain for receptor function and suggest that introduction of an asparagine residue can cause sufficient stabilization of helix-helix interactions in the absence of ligand to activate downstream signaling pathways involved in directing proliferation and differentiation.

BACKGROUND: To test the hypothesis that human sperm DNA could sustain iron-induced oxidative damage and reduce its fertilizing ability, we studied patients with homozygous β-thalassaemia major (HbTh) as a model of iron overload. METHODS: Sperm from six thalassaemic patients and five age-matched controls were assessed by the sperm chromatin structure assay (SCSA) and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL) assay. Semen parameters, endocrine markers of testicular function, iron profiles and the presence of organ dysfunction were also determined. RESULTS: All patients with HbTh were iron overloaded (median ferritin: 2251 µg/l) and had evidence of spontaneous spermatogenesis. Thalassaemic patients had more sperm DNA damage than the controls (P < 0.01). The sperm DNA damage by SCSA and TUNEL were positively correlated (P < 0.05). Sperm motility and TUNEL results were negatively correlated (P < 0.05), while the age of onset of chelation and sperm DNA damage were positively associated with both SCSA (R 2 0.80, P 0.016) and TUNEL data (R 2 0.67, P < 0.044). No other biochemical or clinical data were associated with sperm DNA damage. CONCLUSIONS: The increase in sperm DNA damage and the negative correlation between sperm motility and DNA damage suggest that iron overload in HbTh predisposes sperm to oxidative injury. This finding has important implications in assisted reproductive procedures such as ICSI where there is increased risk of transmitting defective DNA to the offspring.

Summary. Fetal haemopoietic cells continually circulate and migrate into tissues, and thus may have specialized homing capabilities. In this study we investigated the in vitro features of haemopoietic cells in fetal blood and liver which are relevant to homing and engraftment. Fetal cells were examined for long-term culture-initiating cell (LTC-IC) and progenitor content, adhesion molecule expression, cell cycle behaviour and transendothelial migratory activity. The LTC-IC content of fetal CD34+ cells is similar to that of CD34+ cells from cord and adult mobilized blood. In contrast to adult and cord blood CD34+ cells, fetal CD34+ cells were actively cycling (11·0 ± 1·7% and 28 ± 1·1% of fetal blood and liver CD34+ cells, respectively, in S+G2M, P

As a dendritic cell (DC) matures, it becomes more potent as an antigen-presenting cell. This functional change is accompanied by a change in DC immunophenotype. The signal transduction events underlying this process are poorly characterized. In this study, we have investigated the signal transduction pathways involved in the lipopolysaccharide (LPS)-induced maturation of human monocyte–derived DCs (MoDCs) in vitro. We show that exposure of immature MoDCs to LPS activates the p38 stress-activated protein kinase (p38SAPK), extracellular signal–regulated protein kinase (ERK), phosphoinositide 3-OH kinase (PI3 kinase)/Akt, and nuclear factor (NF)-κB pathways. Studies using inhibitors demonstrate that PI3 kinase/Akt but not the other pathways are important in maintaining survival of LPS-stimulated MoDCs. Inhibiting p38SAPK prevented activation of the transcription factors ATF-2 and CREB and significantly reduced the LPS-induced up-regulation of CD80, CD83, and CD86, but did not have any significant effect on the LPS-induced changes in macropinocytosis or HLA-DR, CD40, and CD1a expression. Inhibiting the NF-κB pathway significantly reduced the LPS-induced up-regulation of HLA-DR as well as CD80, CD83, and CD86. Inhibiting the p38SAPK and NF-κB pathways simultaneously had variable effects depending on the cell surface marker studied. It thus appears that different aspects of LPS-induced MoDC maturation are regulated by different and sometimes overlapping pathways.

Dendritic cells may be generated ex vivo from CD34+ progenitor cells or peripheral blood mononuclear cells. Initial reports suggested that monocyte-derived dendritic cells (MoDCs) arise from a proliferating precursor and several groups subsequently reported successful retroviral transduction of these cells, again implying that cell division occurs. As this is of importance in the development of immunotherapy protocols, we investigated whether monocytes proliferate as they differentiate into MoDCs and also their susceptibility to retroviral transduction. During MoDC differentiation, there was a 51 ± 12% reduction in cell number, 98% of cells were in G0/G1, no DNA synthesis was detectable and the cell cycle regulatory proteins pRb and p130 were in the hypophosphorylated forms observed in non-cycling cells. As expected from these results, MoDCs were refractory to transduction with a GALV1 pseudotyped Moloney murine leukaemia virus (MoMLV)-based retroviral vector. In contrast, generation of DCs from purified CD34 progenitors was accompanied by rapid entry into the cell cycle and a 41.1-fold cell expansion at the end of 14 d culture.

When cord blood is used as a source of haemopoietic stem cells for transplantation, fewer cells are required per kg of recipient. This greater engraftment efficiency of cord blood cells may relate to an increased ability to traverse sinusoidal endothelium, a crucial step in the homing of stem cells. We report that freshly isolated cord blood progenitors migrated more efficiently than mobilized adult cells. Cord blood progenitors responded rapidly to growth factor stimulation with an increase in migratory ability within 24 h whereas mobilized adult cells responded only after 72 h (P

We have determined how the phosphorylation of the retinoblastoma family (pRb, p107, and p130) is governed in individual cell cycle phases of Daudi B-cells during cell cycle exit triggered by alpha-interferon (alpha-IFN). alpha-IFN causes dephosphorylation of pRb and loss of p130 phosphorylated Form 3. However, the change in p130 phosphorylation in response to alpha-IFN occurs before dephosphorylation of pRb is complete because loss of p130 Form 3 occurs throughout the cell cycle prior to complete arrest in G1, whereas pRb is dephosphorylated only in G1. In contrast, p107 is dephosphorylated and is then depleted from cells as they exit the cell cycle. p130, predominantly in Form 1, and hypophosphorylated pRb bind an E2F DNA binding site; p130 complexes E2F-4, whereas pRb binds both E2F-4 and E2F-1. The phosphorylated forms of E2F-4 that bind to the E2F DNA site are different from hyperphosphorylated E2F-4, which predominates in primary hemopoietic cells in G0. We conclude that although cell cycle arrest induced by alpha-IFN may be mediated in part by formation of a complex containing p130 and E2F-4, alpha-IFN does not induce hyperphosphorylation of E2F-4, which characterizes primary hemopoietic cells in G0.

Herpes simplex virus (HSV) has often been suggested as a vector for gene delivery to the nervous system although it is also capable of infecting many other cell types. HSV also has the ability to package large genetic insertions so the expression of multiple genes from a single virus is possible. Here we show that a green fluorescent protein (GFP) expressing HSV1 vector can transduce two primary human cell types--quiescent human CD34+ hematopoietic progenitor cells and dendritic cells--which are both hard to transduce by other means. We also show that GFP is an effective marker when expressed from an HSV vector in vivo in the mouse brain. When GFP is expressed together with a second gene (in this case lacZ) from a single virus, transduced GFP-positive CD34+ hematopoietic progenitor cells or dendritic cells can both be generated at an effective efficiency of 100% for the second gene. Here transduction with the vector is combined with flow cytometry allowing GFP-positive cells to be sorted from the untransduced population. Such completely transduced populations of quiescent CD34+ hematopoietic progenitor and dendritic cells cannot easily be achieved by other means, and might thus allow experimental or therapeutic protocols to be carried out requiring high-level transduction which would not otherwise be possible. Such an approach using HSV vectors might also be applicable to other cell types for which transduction is as yet unreliable or of low efficiency.

LMO2is a crucial regulator of normal hematopoiesis but is progressively silenced from the early T-cell progenitor stage of thymic development. Aberrant LMO2 expression leads to a block in differentiation, increased self-renewal and aggressive T-cell acute lymphoblastic leukemia (T-ALL). Although ≈50% of T-ALL patients overexpress LMO2, this can be attributed to a cytogenetic lesion in only ≈10% of patients, leaving a significant portion mechanistically unaccounted for. We recently discovered somatic mutations that create an oncogenic super-enhancer driving TAL1 expression (Mansour et al., 2014, Science). Therefore, we investigated whether comparable mutations may be causing dysregulated LMO2 expression. Aberrant H3K27ac marks indicative of active chromatin were identified prior to and encompassing the non-coding exon 2 of the LMO2 gene by ChIP-seq in DU.528 and PF-382 T-ALL cell lines, both of which exhibit upregulated LMO2 expression but lack chromosomal lesions at this locus. Sequencing across this peak revealed a heterozygous 20bp duplication in PF-382 cells and a heterozygous 1bp deletion in DU.528 cells, located close to a region recently described as an intermediate promoter. Both indels generated a de novo MYB consensus motif. MYB ChIP-seq showed that ≥96% of reads aligned to the mutant rather than the wild-type allele, suggesting that MYB was preferentially recruited to the mutant allele. Heterozygous mutations were also detected in diagnostic samples from 3% (5/159) of pediatric and 6% (10/164) of adult T-ALL patients. Absence of the mutations in 7 available patient-matched remission samples confirmed that they were somatic. The mutations were densely distributed around highly conserved native ETS1, MYB and GATA motifs; 5 patients had an additional MYB site, 3 both a MYB and an ETS1 site, 1 an ETS1 site alone, and 4 had new RUNX1 binding sites. This suggests that this region may have a regulatory role that is exploited by the mutations to constitutively activate LMO2. All 6 mutant-positive patients with available RNA showed LMO2 overexpression as determined by qRT-PCR, consistent with the hypothesis that these mutations activate gene expression. Furthermore, monoallelic LMO2 expression could be demonstrated in DU.528 cells and 3 of 4 informative T-ALL samples using a heterozygous germline SNP. Expression of the mutations in luciferase reporter assays also indicated that they all markedly activated luciferase activity to between 2x and 57x compared to the wild-type sequence. To assess causality between the mutations and LMO2 dysregulation, we used CRISPR/Cas9 genome-editing with a guide RNA designed to target the mutant MYB site in PF-382 cells. Reduction of LMO2 expression to ≤10% of PF-382 mutant activity was observed in a clone where the mutant allele had been reverted to wild-type and in another clone with a single T>C substitution disrupting the mutant MYB binding site. Interestingly, 2 clones that increased the distance between the native and the mutant MYB sites also resulted in a reduction in LMO2 expression to 19% and 25% of PF-382 activity, suggesting that there are functionally limiting spatial constraints on the mutant MYB site in relation to other neighboring transcription factor binding sites. This was further validated by the lack of reduction in LMO2 expression in a clone where the sequence between the two MYB sites was altered but the spacing distance was unchanged. In conclusion, we have identified and functionally validated a novel recurrent mutation hotspot occurring in a non-coding site whereby introduction of additional binding sites for a number of different transcription factors drives monoallelic LMO2 overexpression from a neomorphic promoter in a substantial proportion of both adult and pediatric T-ALL patients. This mechanism of oncogene activation may be relevant to a wide variety of human cancers. Disclosures Fielding: Baxalta: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees.

Adoptive transfer of CMV-specific T cells offers the potential for reconstitution of viral immunity after allogeneic transplantation. However, the logistics of producing virus-specific T-cell clones has limited the application of cellular therapies. We treated 16 patients for CMV infection with polyclonal CMV-specific T-cell lines generated by short-term culture. Massive in-vivo expansions of CMV-specific cytotoxic T lymphocytes were observed, resulting in reconstitution of viral immunity. In eight cases antiviral drugs were not required, and subsequent episodes of reactivation occurred in only two patients. Our findings indicate that application of CMV-specific cell lines is both feasible and effective in a clinical environment.

Patients with sickle cell trait (STr) are usually considered to be asymptomatic. However, complications, including hypercoagulability, increased risk of venous thromboembolism and the exertional exercise syndrome with rhabdomyolysis and sudden death, have been described. The exact cause of these adverse events is unclear. We have investigated two patients, a set of monozygotic twins with STr, to establish their procoagulant activity status as a potential indicator of thrombotic risk. In-vivo thrombin generation was assessed by the measurement of prothrombin fragment 1 + 2 (F1 + 2) and thrombin-antithrombin complexes (TAT). D-dimer was used as a marker of fibrinolytic activity. The potential to generate thrombin was determined using an ex-vivo thrombin generation test (TGT). The impact of red blood cell (RBC)-derived microparticle shedding and RBC rheology were examined. TAT (>60 μg/l) and F1 + 2 (948 pmol/l) were markedly elevated in patient 2 but within the normal reference range in patient 1 (TAT = 2.5 μg/l; F1 + 2 = 138 pmol/l). D-dimer levels (0.9 mg/l FEU) were similarly elevated in both patients. TGT peak thrombin and endogenous thrombin potential (ETP) were elevated to similar degrees in both patients. Flow cytometric analysis for RBC-derived microparticles showed that both patients had elevated levels on two occasions. RBC deformability, blood viscosity and RBC aggregation were normal and similar in both patients. The results demonstrated different coagulation activity in the patients with one patient in a prothrombotic state, suggesting that there may be two levels of hypercoagulability in STr. Measurement of such differences would allow for separation of high and low-risk patients from serious complications.

Background: The contribution of local and systemic inflammation to the pathophysiology of sporadic first trimester miscarriages remains unclear. The objective of this study was to investigate the inflammatory response in the circulation of women presenting with first trimester miscarriage. Methods: Levels of tumour necrosis factor alpha (TNFa), TNF receptors 1 and 2, interferon gamma (IFNg), interleukin (IL)-6 and IL-10 were assayed using cytometric bead arrays in plasma samples from 29 euploid and 21 aneuploid missed miscarriages, 35 normal pregnant controls and 31 non-pregnant women (NPW). Whole blood flow cytometry was carried out with samples from 17 euploid and 16 aneuploid miscarriages, 18 pregnant controls and 13 NPW. Results: The plasma of women with euploid miscarriage contained significantly higher circulating levels of TNFa (P , 0.005), IFNg (P , 0.005), IL-6 (P , 0.005) and IL-10 (P , 0.01) than that of pregnant controls, irrespective of gestational age. Significantly (P , 0.05) higher TNF-R1 levels at 6–9 weeks, and significantly higher TNFa/IL-6 (P , 0.001) and significantly lower TNFa/IL-10 (P , 0.001) and IFNg/IL-10 (P , 0.001) ratios at 10–14 weeks, were also found in euploid miscarriage cases compared with pregnant controls. TNFa/IL-10 ratio in plasma was significantly (P , 0.05) lower in miscarriages with an abnormal karyotype than those with normal karyotype. Normal pregnant women had a significantly higher plasma level of IFNg (P , 0.01) and IFNg/IL-10 ratio (P , 0.005), a significantly (P , 0.005) lower TNF-R1 level, and a significant (P , 0.05) increase in stimulated TNFa in monocytes, compared with NPW. Conclusions: Our data confirm that there is an inflammatory reaction in normal pregnancy compared with the non-pregnant state, which may be disrupted during miscarriage., peer-reviewed

The cytokines interleukin-8 (IL-8) and granulocyte-macrophage colony-stimulating factor (GM-CSF) enhanced the extracellular release of arachidonate metabolites from ionophore-stimulated neutrophils by 145 ± 10% (mean ± S.E.M., n = 13) and 182 ± 11% (n = 16), respectively. To determine whether enhanced leukotriene production mediates the effects of these cytokines on neutrophil activity, two different specific arachidonate 5-lipoxygenase (5-LO) inhibitors, piriprost and MK-886, were used to inhibit leukotriene synthesis. Neither inhibitor affected the upregulation of CD11b β2-integrin expression or priming of superoxide generation stimulated by IL-8 and GM-CSF. It is concluded that leukotrienes do not mediate either the direct or priming effects of these cytokines and that these classes of anti-inflammatory drugs are therefore unlikely to inhibit the effects of IL-8 and GM-CSF on neutrophil activation.

OBJECTIVE: The purpose of this study was to evaluate circulating and intracellular levels of Th1 and Th2 cytokines in women with threatenedmiscarriage (TM) and subsequent outcome. STUDY DESIGN: Plasma levels of tumor necrosis factor (TNF)-receptors 1 and 2, TNF , interferon gamma (IFN ), and interleukins (IL) -6 and -10 were measured by flow cytometric bead assays in 80 women with TM: 53 women with normal outcome and 27 women who miscarried. Fluorescent antibody labeling was also performed on whole blood in a subgroup of 27 women of TM: 16 women with normal outcome and 11 women who miscarried. RESULTS: Monocyte expression of TNF and circulating levels of TNF , IFN , IL-10, IL-6, and TNF-R1 were significantly lower, whereas circulating levels of TNF /IL-10, IFN /IL-10, and TNF /IL-6 ratios were significantly higher, in women with TM who subsequently miscarried, compared with the women with normal outcome. CONCLUSION: An increased Th1 type of immune response, which was similar to that observed in preterm delivery, was found in TM cases that were complicated by a subsequent miscarriage., peer-reviewed

There is considerable uncertainty as to the significance of a high sperm DNA fragmentation index (DFI) for achieving a successful pregnancy.The sperm DFI of 124 patients undergoing 192 IVF cycles and of 96 patients undergoing 155 ICSI cycles was determined using the sperm chromatin structure assay on neat sperm.The rate of continuing pregnancies in ICSI cycles (but not in IVF cycles) showed significant negative correlation (r = -0.184, P = 0.022) with the DFI value. A threshold value of DFI which showed a significant difference (P = 0.005) in rate of continuing pregnancies between higher and lower DFI levels was found for ICSI cycles to beor = 19%, but no such threshold was found for IVF cycles. However, if the threshold ofor = 30% was used for IVF cycles there was a non-significant lowering of the rates of continuing pregnancy and implantation at the higher DFI levels. DFI level had no effect on fertilization rate or on the percentage of embryos having more than 4 cells at Day 3 after fertilization. A high DFI level had a marked significant effect (P = 0.001) on implantation rate in ICSI cycles but not in IVF cycles. A significant positive correlation (r = 0.268, P = 0.001) between DFI and sperm midpiece defects was also noted in the ICSI patients.These observations may help to resolve the issues about how, and to what extent, sperm DNA damage impacts upon the success of IVF and ICSI procedures.

Background. The profound immunodeficiency associated with allogeneic hematopoietic stem cell transplantation is permissive to uncontrolled replication of latent human herpesviridae such as cytomegalovirus. Morbidity and mortality associated with viral dissemination or its treatment are significant. Although adoptive cellular therapy with virus-specific T cells offers the potential for accelerating pathogen-specific immune reconstitution, the risk of induction of graft-versus-host disease and the logistics of production of clonal T cell populations restrict application.Methods. We investigated the ability of cytomegalovirus-specific mixed CD4(+) and CD8(+) T cell lines, generated by short-term ex vivo culture of donor lymphocytes with donor monocyte-derived dendritic cells pulsed with virus lysate, to restore antiviral immunity in 30 allogeneic transplant recipients at high risk of both uncontrolled viral replication and of graft-versus-host disease.Results. There were no immediate toxicities and no excess of graft-versus-host disease. Massive in vivo expansions of cytomegalovirus-specific T lymphocytes occurred, temporally associating with periods of viral replication, suggesting that antigen exposure was necessary for optimal cytomegalovirus-specific immune reconstitution. The expanding populations maintained functional competence in ex vivo re-stimulation assays, promoting reconstitution of durable functional cytomegalovirus-specific immunity and effectively preventing recurrent viral infection and late cytomegalovirus disease.Conclusions. These data confirm the ability of cellular immunotherapy to hasten reconstitution of antiviral immunity following allogeneic transplantation, indicating that significant clinical benefits may be conferred in terms of reduction of secondary viral infection episodes, potentially reducing exposure to the toxicities of antiviral drugs.

Increased expression of Notch signaling pathway components is observed in Kaposi sarcoma (KS) but the mechanism underlying the manipulation of the canonical Notch pathway by the causative agent of KS, Kaposi sarcoma herpesvirus (KSHV), has not been fully elucidated. Here, we describe the mechanism through which KSHV directly modulates the expression of the Notch ligands JAG1 and DLL4 in lymphatic endothelial cells. Expression of KSHV-encoded vFLIP induces JAG1 through an NFκB-dependent mechanism, while vGPCR upregulates DLL4 through a mechanism dependent on ERK. Both vFLIP and vGPCR instigate functional Notch signalling through NOTCH4. Gene expression profiling showed that JAG1- or DLL4-stimulated signaling results in the suppression of genes associated with the cell cycle in adjacent lymphatic endothelial cells, indicating a role for Notch signaling in inducing cellular quiescence in these cells. Upregulation of JAG1 and DLL4 by KSHV could therefore alter the expression of cell cycle components in neighbouring uninfected cells during latent and lytic phases of viral infection, influencing cellular quiescence and plasticity. In addition, differences in signaling potency between these ligands suggest a possible complementary role for JAG1 and DLL4 in the context of KS., Author Summary Kaposi sarcoma herpesvirus (KSHV) is a tumour virus associated with Kaposi sarcoma (KS). Most KS tumor cells are latently infected with the virus, while a small number are lytically infected and produce KSHV. The Notch signaling pathway is highly conserved and important in development and disease. Classical activation of this pathway occurs through direct interaction between ligands and receptors bound to the surface of adjacent cells and influences gene expression in cells receiving the signal. KS tumour cells express Notch pathway components and are sensitive to inhibition of Notch signaling, suggesting this pathway may be important in the development of KS; however, no mechanism behind the classical activation of Notch by KSHV has been established. We describe the molecular mechanisms through which KSHV hijacks the Notch signaling pathway by directly increasing the expression of two Notch ligands (JAG1 and DLL4) through two KSHV genes expressed during latent and lytic infection, respectively. We show the effect of JAG1- and DLL4-stimulated signaling on gene expression in adjacent cells and show that both ligands affect cell cycle-associated genes and may co-operate to permit functional signaling in the context of both latent and lytic infection.

Patients with autosomal dominant (AD), sporadic and X-linked severe congenital neutropenia (SCN) may have mutations in the elastase 2 (ELA2) or Wiskott-Aldrich syndrome (WAS) genes. Homozygous mutations in the HAX1 gene have recently been reported in autosomal recessive (AR) cases of primarily Middle-Eastern descent and the original Kostmann family. We screened 109 predominantly Caucasian SCN kindreds for mutations in these genes; 33 (30%) had 24 different ELA2 mutations, five of them novel, two kindreds (2%) had WAS mutations and four kindreds (4%) had three different HAX1 mutations, two of them novel. One HAX1 mutation (p.Ser43LeufsX11) was found in an AR Ashkenazi Jewish kindred, the other (p.Glu31LysfsX54) in two unrelated British patients with sporadic disease. Microsatellite analysis of the HAX1 locus revealed a common haplotype (maximum distance 4.1 Megabases) for the p.Glu31LysfsX54 patients, suggesting a possible ancestral founder. In functional assays, the level of spontaneous and staurosporine-induced apoptosis was increased in neutrophils from both p.Ser43LeufsX11 patients but not a p.Glu31LysfsX54 patient, suggesting the possible presence of modifying factors. The low incidence of HAX1 mutations in our study suggests that the frequency may vary between racial groups but suggests that irrespective of inheritance or racial origin, SCN patients should be screened for HAX1 mutations.

This study investigated the relationship between male reproductive hormones and sperm DNA damage and markers of oxidative stress in men undergoing infertility evaluation for male factor (n = 66) and non-male factor (n = 63) infertility. Semen samples were analysed for DNA fragmentation index (DFI). Serum samples were analysed for FSH, inhibin B, anti-Mullerian hormone (AMH), testosterone and total antioxidant capacity (TAC). Serum inhibin B was significantly lower in the male factor group compared with the non-male factor group. Inhibin B showed a positive correlation with sperm concentration and motility, and serum AMH showed a positive correlation with sperm concentration and semen volume. DFI was 3-fold higher in the male factor group and showed a negative correlation with sperm motility. Blood plasma TAC was negatively related to sperm concentration. The results confirm that AMH and inhibin B are markers of Sertoli cell function. Sperm DNA damage is moderately increased in male factor infertility, and is negatively associated with sperm motility. A negative association between antioxidant activity and sperm concentration suggests that even minimal oxidative stress may influence sperm concentration. However, there was no significant relationship between hormone concentrations, sperm DNA damage and total antioxidant capacity, suggesting other mechanisms for sperm dysfunction.

Bone disease in multiple myeloma (MM) is due to an increase in osteoclast (OCL) numbers, which is associated with an increase in RANK Ligand and reduction in osteoprotegerin (OPG). Previous studies have shown that systemic administration of recombinant OPG reduces MM bone disease, but the short half life of OPG limits its usefulness. Gene modified mesenchymal stem cells (MSCs) offer a potential means of delivering stable expression of therapeutic proteins.

Background Efficient gene transfer to bone marrow derived mesenchymal stem cells (MSC) would provide an important opportunity to express potent anticancer agents in the tumour microenvironment because of their contribution to the tumour stroma. Methods HIV-based lentiviral vectors were pseudotyped with four different envelope proteins; amphotropic murine leukaemia virus (ampho), murine leukaemia virus (10A1), feline endogenous virus (RD114), and the vesicular stomatitis virus glycoprotein (VSVG). These pseudotypes were examined for transduction efficiency in human bone marrow derived MSC. The effect of lentiviral expression of truncated soluble vascular endothelial growth factor decoy receptor (tsFlk-1) in MSC on growth of Raji cells was determined, both in vitro and in vivo. Results All lentiviral vectors produced significant levels of transduction at an multiplicity of infection (MOI) of 1, those bearing the RD114 envelope glycoprotein consistently produced higher transduction levels (mean 70 ± 6%) compared with the other pseudotyped lentiviral vectors, although there was significant inter-donor variation. Stable transgene expression was achieved after multiple rounds of transduction with VSVG-pseudotyped particles, without alteration in the differentiative capacity of transduced cells. Co-injection of MSC stably expressing tsFlk-1 with Raji Burkitt's lymphoma cells significantly impaired subcutaneous tumour growth in immunodeficient mice when compared to controls where either unmanipulated MSC or GFP-expressing MSC were used. Conclusions Human MSC are easily transduced by pseudotyped lentiviral particles but there is inter-donor variation in transduction efficiency. Gene-modified MSC expressing a gene of therapeutic potential can moderate growth of haematological malignancies. Copyright © 2005 John Wiley & Sons, Ltd.

The prognostic significance of FLT3 mutations in acute promyelocytic leukemia (APL) is not firmly established and is of particular interest given the opportunities for targeted therapies using FLT3 inhibitors. We studied 203 patients with PML-RARA–positive APL; 43% of the patients had an FLT3 mutation (65 internal tandem duplications [ITDs], 19 D835/I836, 4 ITD+D835/I836). Both mutations were associated with higher white blood cell (WBC) count at presentation; 75% of the patients with WBC counts of 10 × 109/L or greater had mutant FLT3. FLT3/ITDs were correlated with M3v subtype (P < .001), bcr3 PML breakpoint (P < .001), and expression of reciprocal RARA-PML transcripts (P = .01). Microarray analysis revealed differences in expression profiles among patients with FLT3/ITD, D835/I836, and wild-type FLT3. Patients with mutant FLT3 had a higher rate of induction death (19% vs 9%; P = .04, but no significant difference in relapse risk (28% vs 23%; P = .5) or overall survival (59% vs 67%; P = .2) at 5 years. In in vitro differentiation assays using primary APL blasts (n = 6), the FLT3 inhibitor CEP-701 had a greater effect on cell survival/proliferation in FLT3/ITD+ cells, but this inhibition was reduced in the presence of ATRA. Furthermore, in the presence of CEP-701, ATRA-induced differentiation was reduced in FLT3/ITD+ cells. These data carry implications for the use of FLT3 inhibitors as frontline therapy for APL.

Purpose: The purpose of this work was to test the suitability of the HM1.24 antigen as a CTL target for immunotherapy of patients with multiple myeloma. Experimental Design: Antigen-specific T cells were generated from patients with multiple myeloma using stimulation with protein-pulsed dendritic cells and tested in ELISPOT and CTL assays. Results: HM1.24-primed T cells responded selectively to HM1.24-loaded autologous peripheral blood mononuclear cells (PBMC) in an IFN-γ ELISPOT assay (median, 342; range, 198-495 IFN-γ–producing cells/105 cf. unloaded PBMC median, 98; range, 7-137; P < 0.05, n = 5) and also to autologous malignant plasma cells (MPC; median, 227; range, 153-335; P < 0.05 when compared with the response to allogeneic MPC median, 57; range, 22-158; n = 5). HM1.24-primed T cells lysed autologous MPC (at 20:1 E/T ratio: median, 48% specific killing; range, 23-88%; at 10:1 E/T ratio: median, 43%; range, 15-80%; n = 12) but not allogeneic MPC. Lysis of autologous MPC was inhibited by anti–MHC class I but not anti–MHC class II antibodies and was blocked by Concanamycin A. Lysis of autologous MPC was blocked by competition with autologous HM1.24-transfected dendritic cells (10:1 ratio with autologous MPC). Unmanipulated, or control plasmid–transfected dendritic cells had no effect on lysis of autologous MPC. Conclusion: Our results indicate that HM1.24 is a promising target for immunotherapy of multiple myeloma.

This report concerns congenitally Na(+)-K(+) leaky red cells of the 'hereditary stomatocytosis' class. Three new isolated cases and one new pedigree are described, and one previously reported case is expanded. In all cases, Western blotting of red cell membranes revealed a deficiency in the 32 kDa membrane protein, stomatin. All showed pronounced cation leaks at 37 degrees C with markedly abnormal intracellular Na(+) and K(+) concentrations, like all other such stomatin-deficient cases. Consistent with recent findings in two previously described British pedigrees, immunocytochemistry demonstrated that the deficiency of stomatin was not complete. On typical blood films, some red cells showed positive stomatin immunoreactivity, while most were negative, although in one case only a minority were negative. All platelets and neutrophils were stomatin positive. The cases differed markedly between themselves with regard to the temperature dependence of the passive leak to K(+). Three showed a simple monotonic temperature dependence, while two showed a minimum at around 20-25 degrees C, such that the cells were extremely leaky at 0 degrees C, giving the phenotype known as 'cryohydrocytosis'. These patients are the only two known cases of stomatin-deficient cryohydrocytosis. Both showed a congenital syndrome of mental retardation, seizures, cataracts and massive hepatosplenomegaly, probably defining a new haemato-neurological syndrome.

The reduced engraftment potential of hematopoietic stem/progenitor cells (HSPCs) after exposure to cytokines may be related to the impaired homing ability of actively cycling cells. We tested this hypothesis by quantifying the short-term homing of human adult CD34+ cells in nonobese diabetic/severe combined immunodeficient (NOD/SCID) animals. We show that the loss of engraftment ability of cytokine-activated CD34+ cells is associated with a reduction in homing of colony-forming cells (CFCs) to bone marrow (BM) at 24 hours after transplantation (from median 2.8% [range, 1.9%-6.1%] to 0.3% [0.0%-0.7%]; n = 3; P < .01), coincident with an increase in CFC accumulation in the lungs (P < .01). Impaired BM homing of cytokine-activated cells was not restored by using sorted cells in G0G1 or by inducing cell cycle arrest at the G1/S border. Blocking Fas ligation in vivo did not increase the BM homing of cultured cells. Finally, we tested cytokine combinations or culture conditions previously reported to restore the engraftment of cultured cells but did not find that any of these was able to reverse the changes in homing behavior of cytokine-exposed cells. We suggest that these changes in homing and, as a consequence, engraftment result from the increased migratory capacity of infused activated cells, leading to the loss of selectivity of the homing process.

Summary. Immune reconstitution after conventional allogeneic transplantation is a major determinant of survival. We conducted a detailed investigation of T- and B-cell immune reconstitution and clinical outcome in 19 patients with multiple myeloma undergoing reduced-intensity stem cell transplantation using in vivo T-cell depletion with alemtuzumab. These patients experienced delayed T-cell recovery, particularly in the naive (CD45 RA+) CD4 compartment. T-cell receptor spectratype analysis showed a reduced repertoire diversity, which improved rapidly after the administration of donor leucocyte infusions and subsequent conversion to full donor T-cell chimaerism. Post-transplant recovery of CD19+ B cells was also delayed for up to 18 months. Spectratype analysis of IgH CDR3 repertoire revealed a gradual normalization in IgM spectratype complexity by 6–12 months after transplant. There was a high incidence of viral infection, particularly cytomegalovirus reactivation, but the regimen-related mortality was low, perhaps because of the very low incidence of acute graft-versus-host disease (GVHD; grade I-II skin GVHD was seen in 5/19 patients). Over 80% of all patients have relapsed at a median of 283 (range 153–895) d after transplant, suggesting that the initially low rate of GVHD comes at a high price with regard to the desired graft-versus-myeloma effect.

Using the p38 stress-activated protein kinase (p38SAPK) inhibitor, SB203580, increased responsiveness of monocyte-derived dendritic cells (MoDCs) to secondary lymphoid chemokine (SLC) and macrophage inflammatory protein 3beta (MIP3beta), following lipopolysaccharide-induced MoDC maturation, was shown to be mediated by the p38SAPK pathway. This was due to the complete abrogation of upregulation of CC chemokine receptor 7, the receptor for MIP3beta/SLC. Once mature, MoDCs utilized both the p38SAPK and phosphoinositide-3 kinase pathways to migrate in response to SLC or MIP3beta. These findings have implications for the mechanism of action of p38SAPK inhibitors, currently in use in clinical trials for patients with autoimmune diseases.

The migration of haemopoietic stem and progenitor cells across endothelium lining bone marrow sinuses is a critical first step in the homing and successful engraftment of these cells. We have previously shown that freshly isolated mobilized peripheral blood CD34+ cells adhere to the endothelial surface but do not transmigrate unless activated by growth factors. The aim of this work was to examine the relationship between cell cycle progression, cell division and migration across endothelium. We now show that the enhanced migration of cytokine-activated cells is selective for cells which are in G0G1 phase of the cell cycle. Thus, the transmigrated population of CD34+ cells was enriched for cells in G0G1 phase, and sorted cells in G0G1 migrated more efficiently than those in S+G2M. Conversely, cells in S+G2M were more adherent to endothelium, a finding that may explain their reduced migration. Using the cytoplasmic dye, carboxyfluorescein diacetate succinimidyl ester, to track the divisional kinetics of CD34+ cells, we found that migration occurred preferentially in non-divided cells. Thus, although CD34+ cells require cytokine activation in order to migrate, cell division is not required for transmigration, which occurs optimally before cells enter S phase. The superior migratory ability of CD34+ cells in G0G1 phase of the cell cycle may have important implications for the homing and engraftment of ex vivo expanded cells.

Fetal haemopoietic cells continually circulate and migrate into tissues, and thus may have specialized homing capabilities. In this study we investigated the in vitro features of haemopoietic cells in fetal blood and liver which are relevant to homing and engraftment. Fetal cells were examined for long-term culture-initiating cell (LTC-IC) and progenitor content, adhesion molecule expression, cell cycle behaviour and transendothelial migratory activity. The LTC-IC content of fetal CD34+ cells is similar to that of CD34+ cells from cord and adult mobilized blood. In contrast to adult and cord blood CD34+ cells, fetal CD34+ cells were actively cycling (11.0 +/- 1.7% and 28 +/- 1.1% of fetal blood and liver CD34+ cells, respectively, in S+G2M, P0.001, compared with cord and adult cells). The striking finding was that fetal haemopoietic cells (both LTC-ICs and committed progenitors) displayed significantly higher levels of migration across endothelium (P0.05 compared with cord, P0.01 compared with adult blood and bone marrow CD34+ cells), which were further increased by chemokines and growth factors. The superior migratory activity of fetal haemopoietic cells may underlie a more efficient homing ability, in keeping with their physiological role.

Under conditions of impaired T-cell immunity, human cytomegalovirus (HCMV) can reactivate from lifelong latency, resulting in potentially fatal disease. A crucial role for CD8+ T cells has been demonstrated in control of viral replication, and high levels of HCMV-specific cytotoxic T-lymphocytes are seen in immunocompetent HCMV-seropositive individuals despite very low viral loads. Elucidation of the minimum portion of the anti-HCMV T-cell repertoire that is required to suppress viral replication requires further study of clonal composition. The ability of dendritic cells to take up and process exogenous viral antigen by constitutive macropinocytosis was used to study HCMV-specific T-cell memory in the absence of viral replication. The specificity and clonal composition of the CD8+ T-cell responses were evaluated using HLA tetrameric complexes and T-cell receptor β chain (TCRBV) spectratypic analyses. There was a skewed reactivity toward the matrix protein pp65, with up to 40-fold expansion of CD8+ T cells directed toward a single peptide-MHC combination. Individual expansions detected on TCRBV spectratype analysis were HCMV-specific and composed of single or highly restricted numbers of clones. There was preferential TCRBV gene usage (BV6.1/6.2, BV8, and BV13 in HLA-A*0201+ individuals) but lack of conservation of CDR3 length and junctional motifs between donors. While there was a spectrum of TCR repertoire diversity directed toward individual MHC-peptide combinations between donors, a relatively small number of clones appeared to predominate the response in each case. These data provide further insight into the range of anti-HCMV responses and will aid the design and monitoring of adoptive immunotherapy protocols.

As a dendritic cell (DC) matures, it becomes more potent as an antigen-presenting cell. This functional change is accompanied by a change in DC immunophenotype. The signal transduction events underlying this process are poorly characterized. In this study, we have investigated the signal transduction pathways involved in the lipopolysaccharide (LPS)-induced maturation of human monocyte-derived DCs (MoDCs) in vitro. We show that exposure of immature MoDCs to LPS activates the p38 stress-activated protein kinase (p38SAPK), extracellular signal-regulated protein kinase (ERK), phosphoinositide 3-OH kinase (PI3 kinase)/Akt, and nuclear factor (NF)-kappaB pathways. Studies using inhibitors demonstrate that PI3 kinase/Akt but not the other pathways are important in maintaining survival of LPS-stimulated MoDCs. Inhibiting p38SAPK prevented activation of the transcription factors ATF-2 and CREB and significantly reduced the LPS-induced up-regulation of CD80, CD83, and CD86, but did not have any significant effect on the LPS-induced changes in macropinocytosis or HLA-DR, CD40, and CD1a expression. Inhibiting the NF-kappaB pathway significantly reduced the LPS-induced up-regulation of HLA-DR as well as CD80, CD83, and CD86. Inhibiting the p38SAPK and NF-kappaB pathways simultaneously had variable effects depending on the cell surface marker studied. It thus appears that different aspects of LPS-induced MoDC maturation are regulated by different and sometimes overlapping pathways.

Farnesol preferentially inhibits proliferation and induces apoptosis of tumour-derived but not non-transformed cell lines. We investigated whether farnesol induces apoptosis of blasts from patients with acute myeloid leukaemia (AML) and leukaemic cell lines, as compared with normal, human primary haemopoietic cells. We show that 30 μM farnesol causes apoptosis of leukaemic cell lines of T- and B-lymphocyte, myeloid or erythroid lineages and primary blasts obtained from patients with AML. However, the same concentration did not kill primary monocytes, or quiescent or proliferating T-lymphocytes. We conclude that farnesol selectively kills AML blasts and leukaemic cell lines in preference to primary haemopoietic cells.

The A-Myb transcription factor is structurally related to the c-myb proto-oncogene and is involved in the control of proliferation and/or differentiation of mature B lymphocytes. We have shown previously by PCR analysis that A-myb is preferentially expressed in CD38+CD39−sIgM− mature B cells. We demonstrate here, using in situ hybridization, that A-mybexpression is restricted to the dark zone of human tonsils and lymph nodes. Furthermore, we show that A-Myb expression is cell cycle regulated both in tonsillar B cells and in Burkitt’s lymphoma cell lines, being detectable only in the S and G2/M phases of the cell cycle and not in G0/G1 phase. Strong proliferation of resting human B cells induced in vitro by a variety of physiologic signals, including anti-μ, CD40 ligand, IL-2, IL-4, IL-6, IL-13, IFN-γ, TNF-α, anti-CD19, and anti-CD20, failed to induce A-myb expression, suggesting that proliferation alone is not sufficient for A-myb expression in the absence of induction of a true centroblast phenotype. Finally, we show that differentiation of germinal center B cells in vitro toward either memory or plasma cells is accompanied by rapid down-regulation of A-myb expression. We conclude that A-myb is a marker of centroblasts generated in vivo.

Abstract 1038 Background and Rationale. Under conditions of iron overload, the iron binding capacity of transferrin is exceeded and non-transferrin-bound iron (NTBI) species appear in the circulation, at concentrations typically within the range of 0.4–10 μM. NTBI species are rapidly cleared, mainly by the liver but also by the heart and endocrine tissues, causing iron overload of these organs. It is known that pre-loading of hepatocytes or cardiomyocytes with iron causes a paradoxical, dose and time-dependent, increase in NTBI clearance by these cells in vitro through mechanisms that are largely undetermined. In an iron overloaded mouse model, the uptake of ferrous iron by myocardium was related to the expression of L-type voltage–gated calcium channels and blockers of these channels reduced iron accumulation in the heart. However, it is unknown whether a similar mechanism underlies NTBI uptake by the liver. Previous work in our laboratory, using the human HuH7 hepatoma cell line, showed that increments in NTBI uptake that occurred following iron pre-loading of cells, were inhibited by the T-calcium channel inhibitor mibefradil. Methods. Flow cytometry and quantitative confocal microscopy were used to assess for changes in the abundance and subcellular distribution of L- and T-type calcium channels by iron-loading (ferric ammonium citrate [FAC]) of HuH7 hepatocytes. These cells were pre-incubated for 24 hours with increasing concentrations of FAC and then fixed (by 4% paraformaldehyde) or fixed and permeabilised (by 0.1% Triton X-100/PBS). Fixed HuH7 cells in suspension were immuno-stained with rabbit polyclonal antibodies against the alpha-1 subunits D (L-type) or H (T-type) and any changes in L- and T-type calcium channels on the cell surface measured by flow cytometry. Confocal microscopy was also performed on fixed and subsequently permeabilised adherent HuH7 cells, which were then immuno-stained by the same antibodies and subjected to fluorescence analysis using the Volocity program (Perkins Elmer) in order to assess intracellular distribution of these channels. Results. At clinically relevant pre-loading concentrations of 2 μM FAC, flow cytometry of fixed cells showed a 38% increase in T-type calcium channels on the outer membrane but no significant change in L-type channels. However, at higher FAC concentrations (20μM and 200 μM), there was a dose dependent rise in the membrane expression of L-type channels but a fall in T-type channels. With 200 μM FAC, the expression of the L-type channel was almost 3x that of the controls (p Confocal microscopy of fixed and permeabilised cells showed similar effects on calcium channels following iron pre-loading. At. the clinically relevant concentrations of 2 μM iron, cellular images and line profiles exhibited greater over-all and outer membrane T-type fluorescence than controls, while L-type channels remained unaffected. By contrast, at higher pre-loading concentrations of FAC (20μM and 200μM), dose dependent increases in L-type fluorescence were observed, particularly on the cell membrane, whereas T-type fluorescence was less than that observed at 2 μM iron and similar to that of untreated cells. Conclusions. These findings show that previously demonstrated up-regulation of transferrin independent iron uptake into HuH7 hepatocytes, following cell pre-loading, are associated with an increase in membrane expression of T-type calcium channels at 2μM iron and of L-type channels at concentrations >20μM iron. Previous findings in our laboratory showing up-regulation of NTBI clearance under these conditions, but with no change in mRNA for L or T type channels, and with inhibition of this enhanced uptake by T-type channel blockers, suggest that these effects occur at a post-transcriptional level. These findings also indicate that use of selective calcium channel blockade could be useful in the treatment of iron overload conditions. Disclosures: No relevant conflicts of interest to declare.

Widespread experience indicates that application of suboptimal concentrations of stimulating ligands (secretagogues) to secretory cells elicits submaximal extents of secretion. Similarly, for permeabilized secretory cells, the extent of secretion is related to the concentration of applied intracellular effectors. We investigated the relationship between the extent of secretion from mast cells (assessed as the release of hexosaminidase) and the degranulation (exocytosis) responses of individual cells. For permeabilized mast cells stimulated by the effector combination Ca2+ plus GTP-gamma-S and for intact cells stimulated by the Ca2+ ionophore ionomycin, we found that exocytosis has the characteristics of an all-or-none process at the level of the individual cells. With a suboptimal stimulus, the population comprised only totally degranulated cells and fully replete cells. In contrast, a suboptimal concentration of compound 48/80 applied to intact cells induced a partial degree of degranulation. This was determined by observing the morphological changes accompanying degranulation by light and electron microscopy and also as a reduction in the intensity of light scattered at 90 degrees, indicative of a change in the cell-refractive index. These results may be explained by the existence of a threshold sensitivity to the combined effectors that is set at the level of individual cells and not at the granule level. We used flow cytometry to establish the relationship between the extent of degranulation in individual rat peritoneal mast cells and the extent of secretion in the population (measured as the percentage release of total hexosaminidase). For comparison, secretion was also elicited by applying the Ca2+ ionophore ionomycin or compound 48/80 to intact cells. For permeabilized cells and also for intact cells stimulated with the ionophore, levels of stimulation that generate partial secretion gave rise to bimodal frequency distributions of 90 degrees light scatter. In contrast, a partial stimulus to secretion by compound 48/80 resulted in a single population of partially degranulated cells, the degree of degranulation varying across the cell population. The difference between the all-or-none responses of the permeabilized or ionophore-treated cells and the graded responses of cells activated by compound 48/80 is likely to stem from differences in the effective calcium stimulus. Whereas cell stimulated with receptor-directed agonists can undergo transient and localized Ca2+ changes, a homogeneous and persistent stimulus is sensed at every potential exocytotic site in the permeabilized cells.

The effect of the chemotactic cytokine, IL-8, on neutrophil function was compared with that of of other cytokines, GM-CSF, G-CSF TNF alpha and IFN-gamma. IL-8 rapidly stimulated a three-fold enhancement of the fMLP-stimulated respiratory burst, but this priming effect was transient compared with the slower and sustained effects of GM-CSF and IFN gamma. Apart from G-CSF, IL-8 was the weakest priming agent and was weaker than GM-CSF in priming arachidonic acid metabolism stimulated by calcium ionophore. When incubated in combination, IL-8 and TNF alpha were highly synergistic in their effects on respiratory burst priming, whereas IL-8 and GM-CSF showed little synergy. In contrast, IL-8 was as potent as GM-CSF at increasing the expression of neutrophil chemotactic peptide receptors and the beta 2 integrin, CD11b. The latter was maximally upregulated within 5 min of stimulation with IL-8, whereas the effect of GM-CSF was much slower. The kinetics of neutrophil respiratory burst priming by IL-8 were the same when measured in whole blood samples and in purified cell suspensions, and IL-8 dose-response curves were similar, showing that the low affinity IL-8 receptors on erythrocytes do not rapidly sequester circulating IL-8. The data suggest that IL-8 plays a minor role in priming neutrophil function and that a more major activity is the regulation of neutrophil adhesion and migration.

Apoptotic cell death plays a critical role in the development of the nervous system. The death of mature nondividing neurons that fail to receive appropriate input from the target field has been extensively studied. However, the mechanisms mediating the extensive cell death occurring in areas of the developing brain where proliferating neuroblasts differentiate into mature nondividing neurons have not been analyzed. We show here that the cell cycle arrest of a proliferating cell of neuronal origin by removal of serum results in either apoptotic cell death or differentiation to a mature nondividing neuronal cell. The proportion of cells undergoing death or differentiation is influenced in opposite directions by treatment of the cells with cyclic AMP and retinoic acid. This suggests that following the withdrawal of signals stimulating neuroblast cell division, neuronal cells either can cease to suppress a constitutive suicide pathway and hence die by apoptosis or, alternatively, can differentiate into a mature neuronal cell. Regulation of the balance between apoptosis and neuronal differentiation could therefore play a critical role in controlling the numbers of mature neurons that form.

The effect of cytokines on phagocytes can be either direct e.g. increasing cell adhesion molecule (CD1 lb) expression, or indirect e.g. enhancing or ‘priming’ an agonist-stimulated activity. rh-IL-8 (Sandoz) (500 ng/ml) upregulated CD11b expression to 255 ± 47% of control (n = 5). When neutrophils were incubated with IL-8 + GMCSF (1 - 100 ng/ml) the effect on CD1 lb expression was additive. Incubation of either purified or whole blood neutrophils with IL-8 rapidly primed fMLP-dependent superoxide production by 297 ± 40%, (n = 17). The amount of IL-8 required to give maximal priming was 100 ng/ml in whole blood, cf 10-50 ng/ml for purified cells, concentrations that did not stimulate a respiratory burst in the absence of an agonist. IL-8 was a weaker primer than GMCSF (10 ng/ml) or TNFα (100U/ml), its effect was transient, with loss of activity by 2 hours. When IL-8 and GMCSF were co-incubated in whole blood assays of the respiratory burst, the priming effect at low GMCSF concentrations (10 pg - 1 ng/ml) was additive, whereas at high GMCSF concentrations (10 ng/ml) the effect was less than with GMCSF alone. Ligand binding studies showed that high concentrations of IL-8 (500 ng/ml) did not alter the binding of 125I-GMCSF to neutrophils. In parallel experiments IL-8 increased FMLP receptor expression from 18,000 to 28,000 receptors/cell with little change in receptor affinity, and co-incubation of IL-8 with GMCSF (10 ng/ml) further increased the number of fMLP receptors to 39,000/cell. Respiratory burst priming by combinations of IL-8 with TNFα was at least additive throughout the whole concentration range. The data suggest that in inflammatory lesions IL-8 has the potential to increase neutrophil activity, especially in the presence of other cytokines such as GMCSF and TNFα.