Transforming growth factor-beta1 plasma levels in stable renal allograft recipients under different immunosuppression.
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Adult↗
Biomedical subjects
J Plum
Publications and source records attributed to J Plum.
Peritoneal sclerosis in peritoneal dialysis patients related to dialysis settings and peritoneal transport properties.
BACKGROUND: Peritoneal sclerosis is a histopathologic finding that is probably causative of long-term system failure in peritoneal dialysis (PD). It may be due to uremic toxicity and the influence of peritoneal dialysate components. We intended to clarify to which degree peritoneal fibrosis and vascular changes were associated with the modalities of PD and the peritoneal transport characteristics. METHODS: Peritoneal biopsies of 41 patients suffering from end-stage renal disease were examined. Sixteen patients were at the initiation of dialysis treatment, and 25 patients were studied during chronic PD treatment [9 patients on continuous ambulatory PD (CAPD) and 16 patients on automatic PD (APD)]. Twenty nonuremic patients undergoing abdominal surgery served as the controls. Samples were taken from the parietal peritoneum under standardized conditions and were examined by light microscopy using different staining techniques, semiquantitative grading, and computer-based histomorphometry. RESULTS: A marked loss of mesothelial cells during PD treatment was only observed in cases with two or more preceding episodes of peritonitis, but an increase of the submesothelial fibrous tissue was a common finding and was related to the cumulative glucose load on PD. Patients on PD also had a significantly increased density of small vessels and capillaries in the submesothelial peritoneal layer (12.8 +/- 6.9 per field vs. 6.6 +/- 2.9 in normal controls, P < 0.01). The wall/lumen index of the vessels was increased indicating vascular sclerosis. The degree of vascularization correlated with the amount of fibrous tissue. Patients characterized as high transporters according to the peritoneal equilibration test (PET) had an increased submesothelial fibrous layer. Patients on APD tended to have an increased membrane diameter submesothelial stroma and vascularization (P = NS), although they were treated for a shorter period of time than the CAPD group. Some of the morphologic changes described could already be observed in uremic patients before the onset of dialysis. CONCLUSION: Further research focusing on the clinical and biochemical backgrounds leading to peritoneal membrane changes is of major importance for developing strategies to improve long-term survival on PD.
Adult↗
Peritoneal dialysis fluids with a physiologic pH based on either lactate or bicarbonate buffer-effects on human mesothelial cells.
Conventional lactate (Lac)-buffered peritoneal dialysis (PD) solutions have turned out to be detrimental to human peritoneal cells, especially because of a low pH. In the present study, we focus on potential differences between Lac and bicarbonate (Bic) as a buffer when adjusted to a physiological pH. All test fluids were buffered with either 40 mmol/L of Lac or 34 mmol/L of Bic, sterile filtered, and adjusted to a pH of 7.4. Osmotic agents used were 1.36% glucose (Glu), 3.86% Glu, 1% amino acids (AA), and 7.5% Glu polymer (Glupoly). Human peritoneal mesothelial cells (HPMCs) were isolated from the omentum majus, grown to confluence, and incubated after the second passage for 15 minutes (37 degrees C and 5% carbon dioxide) with the test fluids. Cytotoxicity was controlled by measuring apoptotic and necrotic cells with cytofluorometry. Aerobic cell metabolism (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide [MTT] assay) and intracellular adenosine triphosphate (ATP) concentrations were measured to assess cell viability. Release of interleukin-6 (IL-6) from HPMCs was determined as a parameter of cellular host defense. No significant difference in apoptosis or necrosis rates was found between the solutions adjusted to normal pH. However, in the MTT assay, Bic solutions were superior to corresponding Lac pendants at an identical pH of 7.4 (P < 0.01). Intracellular ATP concentrations reflected a very similar pattern (P < 0.05). Glupoly in combination with Lac showed an impaired pattern with both the MTT and ATP assays. Regarding IL-1beta-stimulated IL-6 release, there was a small, but not significantly better, response for Bic. Differences in manifest cell cytotoxicity reflected by apoptosis and necrosis rates could not be detected comparing PD solutions buffered with Lac or Bic at a physiological pH. However, distinct parameters of cell metabolism were superior with Bic compared with Lac. Especially Glupoly was inferior in combination with Lac as a buffer.
Adenosine Triphosphate↗
Comparison of body fluid distribution between chronic haemodialysis and peritoneal dialysis patients as assessed by biophysical and biochemical methods.
BACKGROUND: The control of extracellular volume is a key parameter for reducing hypertension and the incidence of cardiovascular mortality in dialysis patients. In recent years bioimpedance measurement (BIA) has been proven as a non-invasive and accurate method for measuring intracellular and extracellular fluid spaces in man. In addition, plasma atrial natriuretic peptide (ANP) and cyclic guanosine monophosphatase (cGMP) concentrations have been shown to reflect central venous filling. Using these methods, we compared body fluid status between stable patients on haemodialysis and peritoneal dialysis. METHODS: Thirty-nine chronic haemodialysis patients, 43 chronic peritoneal dialysis patients and 22 healthy controls were included in the study. Multifrequency BIA was performed using the Xitron BIS4000B device (frequencies from 5 to 500 kHz were scanned and fitted) in patients before and after haemodialysis. Peritoneal dialysis patients were measured after drainage of the dialysate. Plasma ANP and cGMP levels were measured in plasma using a (125)I solid phase RIA. Serum albumin concentrations and serum osmolality were measured in all patients. The body fluid data were analysed in relation with the clinical findings. RESULTS: Total body water (TBW) was 0.471+/-0.066 l/kg before haemodialysis and 0.466+/-0.054 l/kg after haemodialysis. Peritoneal dialysis patients had a TBW (0.498+/-0.063 l/kg) that was greater than the before and after dialysis values of haemodialysis patients. The extracellular body fluid (V(ecf)) was increased pre-haemodialysis. It was even greater in peritoneal dialysis patients compared with patients both pre- and post-haemodialysis (pre 0.276+/-0.037 l/kg; post 0.254+/-0.034 l/kg; peritoneal dialysis 0.293+/-0.042 l/kg, P<0.05). However, plasma ANP concentrations (representing intravascular filling) in peritoneal dialysis patients were comparable with post-haemodialysis values (284+/-191 pg/ml vs 286+/-144 pg/ml). The correlation coefficient between sysRR and V(ecf) was r=0.257 in haemodialysis (P=0.057) and r=0.258 in peritoneal dialysis (P<0.05). A significant negative correlation was found between serum albumin and V(ecf)/TBW in peritoneal dialysis patients (r= -0.624). CONCLUSION: Body fluid analysis by BIA demonstrated that TBW and V(ecf) were increased in peritoneal dialysis patients, and were comparable or even greater than values found before haemodialysis. However, plasma ANP levels indicated that intravascular filling was not increased in peritoneal dialysis. The ratio of V(ecf) to TBW was correlated to systolic pressure and negatively to serum albumin in peritoneal dialysis patients.
Adult↗
The anti-proliferative effect of calcitriol on HL-60 cells is neutralized by uraemic biological fluids.
BACKGROUND: It has been demonstrated that uraemic serum/ultrafiltrate inhibits cell-mediated immune response in vitro, and that it suppresses calcitriol synthesis and its biological actions. METHODS: In the present in vitro study, the effect of calcitriol, uraemic ultrafiltrate (UUF) and a combination of both on the human promyelocytic leukaemia cell line, HL-60, was studied by evaluating bromodeoxyuridine (BrdU) incorporation into the DNA, luminol-amplified chemiluminescence (CL) production, expression of CD14, and levels of vitamin D receptor mRNA (VDR mRNA) and CD14 mRNA. RESULTS: The ability of calcitriol to block cell proliferation (37.4+/-5.4 to 30.5+/-5.6% cells incorporating BrdU, P:<0.01) was neutralized when UUF was applied together with calcitriol (53.4+/-21.3% cells incorporating BrdU, P:<0.01 vs calcitriol alone). Similarly to what was observed for BrdU incorporation, the CL production of HL-60 cells was enhanced in the presence of calcitriol (20126+/-10154 to 61528+/-24021 cpm, P:<0.01), and was suppressed again in the presence of calcitriol and UUF (20916+/-12075 cpm, P:<0.01 vs calcitriol alone); finally UUF also inhibited the calcitriol-induced CD14 expression (71.1+/-11.2 to 54.9+/-17.7% CD14 positive cells, P:<0.05). On the other hand, the calcitriol-induced CD14 mRNA levels were not significantly different in the presence of calcitriol and UUF compared to calcitriol alone. This points to an inhibition by UUF at a post-transcriptional level. Similar data were found for VDR mRNA levels. UUF was fractionated by HPLC in four fractions, hydrophilic uraemic solutes being eluted first (F1) and hydrophobic solutes being eluted last (F4); fractions 1, 2 and 3 simultaneously affected both BrdU incorporation and CL production in a significant way. CONCLUSIONS: It is concluded that UUF contains factors that impair calcitriol-activated function of HL-60 cells. Hence, the differentiation and immune response of these promyelocytic leukaemia cells, as induced by the supplementation of calcitriol, is neutralized in the presence of uraemic biological fluids. This may be of relevance for the propensity to infection and malignancy of the uraemic patient.
Biological Factors↗
Recent increase in diagnoses of HIV infections based on surveillance system data in Belgium.
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Adult↗
Exposure to HIV-1 during delivery and mother-to-child transmission.
BACKGROUND: The correlation between the presence of HIV-1 in maternal cervicovaginal secretions and in the infant's oro-pharyngal secretions at birth, and mother-to-child HIV transmission (MTCT) were examined to obtain a better understanding of its mechanism. METHODS: Women without medical and obstetrical complications, living within a reasonable distance of the government hospital in Mombasa, Kenya, were recruited after informed consent. Maternal and infant characteristics were collected. Polymerase chain reaction was used to detect HIV-1 in cervico-vaginal and oro-pharyngal secretions. Infants were tested for HIV-1 by polymerase chain reaction within 48 h and at 6 weeks after delivery. RESULTS: Between April 1998 and April 1999, 228 woman-infant pairs were included in the study. HIV-1 DNA in cervico-vaginal secretions was independently associated with HIV-1 maternal viral load and with infant birth-weight, whereas HIV-1 RNA was associated with maternal viral load and maternal age. HIV-1 DNA in the oropharyngal secretions was also independently associated with maternal viral load. MTCT rate at the age of 6 weeks was 23.6%. Intrapartum and early postpartum HIV transmission was independently associated with maternal viral load [adjusted odds ratio (OR), 1.6; 95% confidence interval (CI),1.0-2.7], detection of HIV-1 RNA in cervico-vaginal secretions (adjusted OR, 3.2; 95% CI, 1.5-7.3) and of HIV-1 DNA in oro-pharyngeal secretions (adjusted OR, 3.2; 95% CI, 1.1-9.0). DISCUSSION: As far as is known, this is the first study showing that infant exposure to HIV-1 in the birth canal and the presence of HIV-infected cells in the infant's oropharyngeal cavity are independently associated with intrapartum and early postpartum MTCT. It supports the hypothesis that MTCT could occur through the oral route.
Bodily Secretions↗
Langerhans cells that have matured in vivo in the absence of T cells are fully capable of inducing a helper CD4 as well as a cytotoxic CD8 response.
Langerhans cells (LCs) are immature dendritic cells (DCs) present in the skin epithelium. Upon Ag exposure, they migrate to the draining lymph nodes where they mature into potent stimulators of naive T cells. The aim of this study was to investigate the influence of T cells on LC migration and maturation. Therefore, the in vivo migration and maturation of LCs after sensitization with the hapten FITC was compared between C57BL/6 or BALB/c mice used as positive controls, and recombination activating gene (RAG) 1 knockout (-/-) mice or SCID mice used as T cell-deficient mice. Phenotypically, there was no difference between migrated LCs from RAG1-/- or SCID mice vs normal C57BL/6 or BALB/c mice: both populations of FITC+ cells had a dendritic morphology and a mature phenotype as they expressed high levels of MHC class II molecules and costimulatory molecules CD80, CD86, and CD54. Sorted migrated LCs of RAG1-/- or SCID mice were efficient stimulators of allogeneic T cells and Ag-specific CD4+ T cells. The same results were found if migrated LCs were fixed instead of irradiated, excluding the possibility that LCs derived from RAG1-/- or SCID mice would mature in the presence of T cells during the stimulation tests. Importantly, fixed migrated LCs of RAG1-/- mice were also efficient stimulators of cytotoxic CD8+ T cells. These data suggest that T cells are not required for full maturation of LCs.
Animals↗
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)
Adult↗
Signals from the IL-9 receptor are critical for the early stages of human intrathymic T cell development.
Highly purified human CD34+ hemopoietic precursor cells differentiate into mature T cells when seeded in vitro in isolated fetal thymic lobes of SCID mice followed by fetal thymus organ culture (FTOC). Here, this chimeric human-mouse FTOC was used to address the role of IL-9 and of the alpha-chain of the IL-9 receptor (IL-9Ralpha) in early human T cell development. We report that addition of the mAb AH9R7, which recognizes and blocks selectively the human high affinity alpha-chain of the IL-9R, results in a profound reduction of the number of human thymocytes. Analysis of lymphoid subpopulations indicates that a highly reduced number of cells undergo maturation from CD34+ precursor cells toward CD4+CD3-CD8-CD1+ progenitor cells and subsequently toward CD4+CD8+ double positive (DP) thymocytes. Addition of IL-9 to the FTOC resulted in an increase in cell number, without disturbing the frequencies of the different subsets. These data suggest that IL-9Ralpha signaling is critical in early T lymphoid development.
Adjuvants, Immunologic↗
[Atrial natriuretic peptide as an indicator of mild postoperative cardiac dysfunction after uncomplicated bypass surgery].
Plasma levels of ANP (pg/ml; radioimmunoassay) as a parameter for postischemic dysfunction and levels of Troponin T (TnT) (ng/ml; ELISA test) as a parameter for postischemic cellular damage were determined in 15 patients with coronary artery disease (CAD) (mean age: 58 +/- 6.1 years; 13 m, 2 w; with no history of myocardial infarction and no signs for congestive heart failure) prior to, during and after extracorporal circulation (ECC). Under standardized conditions during the ECC basic parameters concerning the cardial hemodynamic (heart rate (HR); systolic (RRsys, mmHg), diastolic pressure (RR dia, mmHg) central venous pressure (CVP, mmHg); left atrial pressure (LAP, mmHg); left ventricular enddiastolic pressure (LVEDP, mmHg)) and ECG monitoring blood samples were performed: 1) prior to operation (op); 2) prior to CPB; 3) 1 h CPB; 4) 5 min after CPB; 5) 1 h after CPB; 6) 6 h postoperative (postop); 7) 24 h postop; 8) 48 h postop; 9) 10 days postop. Also the left atrial diameter (LAD, mm) and the left ventricular enddiastolic diameter at Q (LVEDD, mm) pre- and postop were documented with m-mode echocardiography (Echo) and ejection fraction (EF, %) was calculated. The bypass operations were performed with intermittent aortic cross-clamping with open venae cavae (CVP: 0-5 mmHg) and moderate hypothermia. For the determination of ANP levels and TnT levels in arterial and venous blood, a double-antibody (AB) radioimmunoassay and an ELISA test were used. Concerning the patients with CAD there was a maximal increase of ANP from preoperative 90 +/- 10 (M +/- SEM) pg/ml (p < 0.05) up to intraoperative 380 +/- 38 pg/ml. Ten days postop, the ANP level was with 262 +/- 33 pg/ml still increased threefold in comparison to the preoperative level. TnT showed an increase from preoperative 0.02 +/- 0.01 ng/ml up to intraoperative 3.44 +/- 0.47 ng/ml. Ten days postop the TnT concentration was at the preoperative level with 0.13 +/- 0.11 ng/ml. Five minutes after bypass up to 48 h postop, ANP and TnT levels were correlated (p < 0.05, r = 3.4). There was an increase of the LAD from preoperative 42.2 +/- 1.1 mm up to 46.8 +/- 1.2 mm (p < 0.05) 10 days postop as determined by m-mode echo. LVEDD and EF changed from preoperative 51.1 +/- 0.9 mm and 73 +/- 2% to 54.5 +/- 1.2 mm and 65 +/- 4% 10 days postop. The significant increase of TnT (172-fold) indicates the cellular, myocardial injury, caused by the operation without signs in ECG recordings and no signs of congestive heart failure. The significantly increased ANP level up to the 10th day postop indicate sa very sensitive prolonged, postischemic dysfunction, which is not compensated 10 days postop.
Adult↗
Efficiency of transgenic T cell generation from gene-marked cultured human CD34+ cord blood cells is determined by their maturity and the cytokines present in the culture medium.
Success of gene therapy for diseases affecting the T cell lineage depends on the thymic repopulation by genetically engineered hematopoietic progenitor cells (HPC). Although it has been shown that retrovirally transduced HPC can repopulate the thymus, little information is available on the effect of the culture protocol. Moreover, for expansion of the number of HPC, cytokine supplemented culture is needed. Here, we transduced purified human umbilical cord blood (CB) CD34+ cells in cultures supplemented with various combinations of the cytokines thrombopoietin (TPO), stem cell factor (SCF), flt3/flk-2 ligand (FL), interleukin-3 (IL-3) and IL-6, and investigated thymus-repopulating ability of gene-marked HPC in vitro. Irrespective of the cytokine cocktail used, transduced CD34+CD38- CB cells, expressing the marker green fluorescent protein (GFP) encoded by the MFG-GFP retrovirus, have both superior proliferative and thymus-repopulating potential compared with transduced CD34+CD38+ CB cells. Effectively transduced GFP+CD34+CD38- HPC, cultured for 3 or 17 days, more readily generated T cells than GFP- HPC from the same culture. The reverse was true in the case of CD34+CD38+ HPC cultures. Finally, our results indicate that the number of GFP+ T cell progenitors actually increased during culture of CD34+CD38- HPC, in a magnitude that is determined by the cytokine cocktail used during culture.
Animals↗
Prostaglandin E1: a new agent for the prevention of renal dysfunction in high risk patients caused by radiocontrast media? PGE1 Study Group.
BACKGROUND: Acute renal failure following the administration of radiocontrast media (RCM) is a complication found especially in patients with impaired renal function. Within the limits of a pilot study, the objective was to (a) show the effectiveness and compatibility of prostaglandin E(1) (PGE(1)=Alprostadil) in preventing acute renal failure in patients with elevated levels of serum creatinine and (b) to identify the most appropriate PGE(1)-dose. METHODS: 130 patients with renal impairment (serum creatinine >/=1.5 mg/dl) were included in the study prior to intravascular RCM injection. The patients received one of three different doses of PGE(1) (10, 20, or 40 ng/kg bodyweight/min) or placebo (physiologic sodium chloride solution) intravenously over a time period of 6 h (beginning 1 h prior to RCM application). Serum creatinine was measured 12, 24, and 48 h post RCM-application and creatinine clearance was determined with two 12 h collection periods, as well as one 24 h collection within 48 h post RCM administration. Adverse events during PGE(1) administration were recorded. RESULTS: In the placebo group, the mean elevation of serum creatinine was markedly higher (0.72 mg/dl) 48 h after RCM administration compared with the three PGE(1) groups (0.3 mg/dl in the 10 ng/kg/min group, 0. 12 mg in the 20 ng/kg/min group, and 0.29 mg/dl in the 40 ng/kg/min group). No clinically relevant changes were seen regarding the creatinine clearance in the four groups examined. CONCLUSIONS: Results from this pilot-study suggest that intravenous PGE(1) may be used efficaciously and safely to prevent RCM-induced renal dysfunction in patients with pre-existing impaired renal function.
Acute Kidney Injury↗
Human T lymphopoiesis. In vitro and in vivo study models.
Successive steps in T lymphocyte differentiation and T potential of human stem cells (HSC) can be tested in the following models: (a) the infusion of cells in NOD-SCID mice, (b) the injection of cells in renconstituted SCID/hu mice, (c) the differentiation of cells in fetal thymus organ culture (FTOC), and (d) on thymic stromal layers. Using mixed human-murine FTOC, we showed (a) TCR alpha beta, TCR gamma delta lymphocytes, NK cells, and dendritic cells complete their differentiation, (b) IL-7R alpha signaling and IL-7 are essential, (c) a detailed phenotypic and functional analysis of discrete successive steps of positively selected thymocytes, (d) an efficient transduction of genes in HSC with persistent gene expression throughout the T-lymphocyte differentiation, and (e) adaptation to submerging high oxygen culture increases the test sensitivity to a clonal assay. Other approaches are the in vivo SCID/hu reconstitution model. With this method small fragments of human fetal liver and thymus are implanted under the kidney capsule of an adult SCID mouse with result in an impressive human thymus organ, six months after transplantation. We use this model to study thymus T-cell developmental kinetics, development of gene-marked precursor cells and thymic homing of precursor cells.
Adult↗
Interruption of reverse transcriptase inhibitors or a switch from reverse transcriptase to protease inhibitors resulted in a fast reappearance of virus strains with a reverse transcriptase inhibitor-sensitive genotype.
OBJECTIVES: To study the effect of the interruption of reverse transriptase inhibitor (RTI) therapy or a switch from RTI to protease inhibitors, on the genotypic drug-resistance pattern of plasma HIV-1. METHODS: Nine patients who completely stopped all medication, and five patients who switched from a treatment with RTI to a regimen containing protease inhibitors only, were studied. Direct sequencing of the plasma HIV-1 RT and protease gene was performed on follow-up samples taken before and after the interruption of treatment. RESULTS: Comparison of the amino acid sequence of the RT and protease genes in successive samples showed the rapid reappearance of wild-type viral variants in 12 of the 14 patients studied. Wild-type virus replaced the mutant strains 14 days to 2 months after the interruption of therapy, even in patients with a long treatment history. CONCLUSION: The results of this study indicate the sustained lower fitness of mutant strains in vivo. As a result, wild-type virus remains capable of outcompeting the RT or protease mutant strains very fast after removal of the drug. These findings highlight the importance of 'treatment history' in addition to genotypic and phenotypic markers determined at one time-point, when making therapeutic decisions for patients.
Amino Acid Substitution↗
Thymic repopulation by CD34(+) human cord blood cells after expansion in stroma-free culture.
Thymic repopulation by transplanted hematopoietic progenitor cells (HPC) is likely to be important for long-term immune reconstitution and for successful gene therapy of diseases affecting the T-cell lineage. However, the T-cell progenitor potential of HPC, cultured in vitro for cell number expansion and gene transfer remains largely unknown. Here, we cultured highly purified human umbilical cord blood (CB) CD34(+)CD38(-) or CD34(+)CD38(+) cells for up to 5 weeks in stroma-free cultures supplemented with various combinations of the cytokines thrombopoietin (TPO), stem cell factor (SCF), flt3/flk-2 ligand (FL), interleukin-3 (IL-3), and IL-6 and investigated thymus-repopulating ability of expanded cells in vitro and in vivo. After up to 5 weeks of culture in IL-3 + SCF + IL-6 or TPO + FL + SCF supplemented medium, the progeny of CD34(+)CD38(-) CB cells generated T cells and natural killer cells in the thymus. Limiting dilution experiments demonstrated increase in the number of T-cell progenitors during culture. After 3 weeks of culture, gene marked CD34(+)CD38(-) CB cells injected in the human thymus fragment transplanted in severe combined immunodeficient (SCID) mice (SCID-hu) generated thymocytes expressing the retroviral encoded marker gene GFP in vivo. Thus, our results show that the progeny of CD34(+)CD38(-) CB cells cultured for extensive periods, harbor thymus-repopulating cells that retain T-cell progenitor potential after expansion and gene transfer.
Animals↗
Human immunodeficiency virus nef gene expression affects generation and function of human T cells, but not dendritic cells.
Human immunodeficiency virus (HIV)-infected individuals develop an acquired immune deficiency syndrome (AIDS) due to loss in their lymphocyte numbers and cellular defects in T cells and antigen-presenting cells (APC). HIV infection of the thymus results in deficient replenishment of the peripheral naive T-cell pool. The HIV nef gene was shown to be important for progression towards AIDS and cellular depletion of the infected thymus. Here, we demonstrate by retroviral gene transfer that nef expression, in the absence of other HIV genes, impaired human thymic T-cell development. Thymocytes were generated in reduced numbers and downmodulated CD4 and CD8beta cell surface expression. T cells grown from nef-expressing thymocytes were hyperproliferative in vitro upon T-cell receptor triggering. Mature dendritic cells (DC) were functional and had normal surface CD4 levels despite nef expression. Thus, nef expression alone may contribute to AIDS development by reduced T-cell generation and T-cell hyperresponsiveness.
Animals↗
In vitro intrathymic differentiation kinetics of human fetal liver CD34+CD38- progenitors reveals a phenotypically defined dendritic/T-NK precursor split.
Human CD34+CD38- hematopoietic precursor cells from fetal liver are able to develop into T, NK, and dendritic cells in a hybrid human/mouse fetal thymic organ culture (FTOC). In this report, we pay particular attention to the early events in differentiation of these precursor cells. We show that the CD34+CD38- precursor cells, which are CD4-CD7-cyCD3-HLA-DR-/++ (cy, cytoplasmatic), differentiate into a CD4+ population that remained CD7-cyCD3-HLA-DR++ and a CD4- population that expressed CD7 and cyCD3. The CD4+CD7-cyCD3- cells differentiate into phenotypically and functionally mature dendritic cells, but do not differentiate into T or NK cells. The CD4-CD7+cyCD3+ population later differentiates into a CD4+CD7+cyCD3+HLA-DR- population, which has no potential to differentiate into dendritic cells but is able to differentiate into NK cells and gammadelta and alphabeta T lymphocytes. These findings support the notion that the T/NK split occurs downstream of the NK/dendritic split.
ADP-ribosyl Cyclase↗