Tissue Factor Activity of Syncytiotrophoblast Plasma Membranes and Tumoral Trophoblast Cells in Culture

During pregnancy, important modifications of hemostasis occur resulting in mothers in hypercoagulability and the role of placental cells such as trophoblast cells has been hypothesized. In this study, we first showed that syncytiotrophoblast plasma membranes, isolated from normal human placenta, expressed a strong tissue factor (TF) activity. We then studied TF activity of two continuous trophoblast cell lines (JEG-3 and BeWo) in comparison to human umbilical vein endothelial cells (HUVEC) and transformed human endothelial cells (ECV-304). TF assays were performed on intact detached confluent cells. Unstimulated JEG-3 and BeWo cells exhibited a very high TF activity which slightly increased after 2 to 4 h TNF-α stimulation. In contrast, HUVEC and ECV-304 had a lower basal TF activity which was mainly inducible by TNF-a, with a maximum effect after 4 to 6 h stimulation. For both cell types, TF activity was decreased to basal value after 16-hour TNF-α stimulation. These results support that trophoblast cells are able to express TF but the involvement of this property in the hemostatic physiological changes observed during pregnancy, remains to be demonstrated.

Developing and validating a practical decision support tool (DST) for biomass selection on marginal land

Marginal, often contaminated, sites exist in large areas across the world as a result of historic activities such as industry, transportation and mineral extraction. Remediation, or other improvements, of these sites is typically only considered for sites with high exploitation pressure and those posing the highest risks to human health or the environment. At the same time there is increasing competition for land resources for different needs such as biofuel production. Potentially some of this land requirement could be met by production of biomass on brownfield or other marginal land, thereby improving the land while applying the crop cultivation as part of an integrated management strategy. The design and decision making for such a strategy will be site specific. A decision support framework, the Rejuvenate DST (decision support tool) has been developed with the aim of supporting such site specific decision making. This tool is presented here, and has been tested by applying it to a number of case study sites. The consequent SWOT (strength, weakness, opportunities and threats) analysis is discussed and evaluated. The DST was found to be systematic, transparent, and applicable for diverse sites in France, Romania and Sweden, in addition to the sites to which it was applied through its development. The DST is regarded as especially useful if applied as a checklist in an iterative way throughout the decision process, from identifying potential crops to identifying knowledge gaps, working/non-working management strategies and potential risks. The DST also provides a structure promoting effective stakeholder engagement.

Association between the SDF1-3'A allele and high levels of CD34(+) progenitor cells mobilized into peripheral blood in humans

Some patients unexpectedly fail to mobilize sufficient numbers of haematopoietic progenitor cells (HPCs) into the peripheral blood for autologous transplantation. Considering the important role of the chemokine stromal cell-derived factor 1 (SDF-1) in HPC homing, we investigated a possible relationship between SDF1 gene polymorphism and HPC mobilization capacity in 63 patients with malignancy. Some 67% of the good mobilizers (> or = 50 CD34(+) cells/microl) and only 36% of the intermediate/poor mobilizers were SDF1-3'A allele carriers (P = 0.032). In multivariate analysis, the presence of the SDF1-3'A allele was the only factor predictive of good CD34(+) cell mobilization (P = 0.025). This is the first report showing the involvement of genetic factors for HPC mobilization in humans and suggests a significant role for SDF-1 in this process.

Development of an ex vivo model of pig kidney perfused with human lymphocytes. Analysis of xenogeneic cellular reactions

BACKGROUND

Because of the explosive nature and the extremely rapid process of hyperacute rejection (HAR), significant infiltration of the xenograft by immunocompetent cells is not observed, and the role and the mechanism of action of cell-mediated rejection in discordant xenografts are therefore still under discussion.

METHOD

We developed an experimental approach using pig kidneys perfused with human peripheral blood lymphocytes (PBL) in which the immunologic barrier of hyperacute rejection was excluded and which mimics the in vivo situation.

RESULTS

PBL retention in the kidney was evaluated at 20-minute intervals for 3 hours. Retention increased from 30% to 80% with the time of perfusion and was specific because significantly fewer syngeneic lymphocytes were retained. Phenotype analysis of recovered PBL showed a significant decrease in natural killer (NK) cells. Immunohistochemical studies revealed the presence of NK cells and T lymphocytes in the glomerular and interstitial tubular structures of the kidney. Functional studies showed a progressive cessation of diuresis and augmentation of renal vascular resistance when the kidney was perfused with PBL. Electron microscopy examinations of kidney sections perfused with PBL showed swollen endothelial zones, suggesting alterations to and damage of the endothelium.

CONCLUSIONS

This system provides a valuable model for the study of early discordant xenogeneic cellular rejection and demonstrates the predominance of xenograft infiltration by NK cells.

[Anti-pig xenogeneic response by human CD4+ T-lymphocytes]

When considering the hypothesis of xenotransplantation, and if it becomes possible to control hyperacute and delayed vascular rejection, the recognition of porcine graft by human T CD4+ lymphocytes could still constitute a very important barrier. The direct recognition of porcine MHC class II molecules (SLA-DR and SLA-DQ) by human TCR has been demonstrated in vitro. It is accompanied by a proliferative lymphocytic response, as co-stimulatory molecules are able to interact across the species barrier. In vivo, this type of recognition only applies to porcine cells with antigen-presenting functions, mainly the graft dendritic cells which emigrate into the recipient lymphoid organs. The other recognition pathway is indirect, whereby the recipient dendritic cells capture porcine xenoantigens in the graft, then process and present them to the lymphocytes in the lymphoid organs. This indirect pathway can be shown in vitro by utilizing porcine MHC class II-negative endothelial cells. In this model, human purified T CD4+ lymphocyte proliferation is tightly dependent on the presence of human antigen-presenting cells and their HLA class II molecules. As the xenogenic peptides all differ from self peptides, the indirect T-cell response will be very strong and probably difficult to control.

Trophoblast cell line resistance to NK lysis mainly involves an HLA class I-independent mechanism

The lack of classical HLA molecules on trophoblast prevents allorecognition by maternal T lymphocytes, but poses the problem of susceptibility to NK lysis. Expression of the nonclassical class I molecule, HLA-G, on cytotrophoblast may provide the protective effect. However, the class I-negative syncytiotrophoblast escapes NK lysis by maternal PBL. In addition, while HLA-G-expressing transfectants of LCL.721.221 cells are protected from lymphokine-activated killer lysis, extravillous cytotrophoblast cells and HLA-G-expressing choriocarcinoma cells (CC) are not. The aim of this work was therefore to clarify the role of HLA class I expression on trophoblast cell resistance to NK lysis and on their susceptibility to lymphokine-activated killer lysis. Our results showed that both JAR (HLA class I-negative) and JEG-3 (HLA-G- and HLA-Cw4-positive) cells were resistant to NK lysis by PBL and were equally lysed by IL-2-stimulated PBL isolated from a given donor. In agreement, down-regulating HLA class I expression on JEG-3 cells by acid treatment, masking these molecules or the putative HLA-G (or HLA-E) receptor CD94/NKG2 and the CD158a/p58.1 NKR with mAbs, and inducing self class I molecule expression on JAR cells did not affect NK or LAK lysis of CC. These results demonstrate that the resistance of CC to NK lysis mainly involves an HLA class I-independent mechanism(s). In addition, we show that the expression of a classical class I target molecule (HLA-B7) on JAR cells is insufficient to induce lysis by allospecific polyclonal CTL.

Fast detection of tissue factor and tissue factor pathway inhibitor messenger RNA in endothelial cells and monocytes by sensitive reverse transcription-polymerase chain reaction

We developed fast and sensitive reverse transcription-polymerase chain reaction (RT-PCR) procedures to study the expression of tissue factor (TF) and tissue factor pathway inhibitor (TFPI-1) mRNA in human endothelial cells and monocytes. The sensitivity of the technique was checked by performing RT-PCR with limited numbers of cells. Cells were stimulated either with tumor necrosis factor (TNF-alpha) or endotoxin to induce TF mRNA expression or with phorbol ester to increase TFPI-1 mRNA expression. Thus, RT-PCR specific for TF mRNA provided detection from as few as 10(3) TNF-alpha stimulated endothelial cells and 5 x 10(2) monocytes stimulated by endotoxin. TF mRNA expression was increased by TNF-alpha in endothelial cells and in monocytes stimulated by endotoxin. Elevated expression of TF mRNA in monocytes without stimulation by endotoxin was mainly related to cell adhesion. TFPI-1 mRNA was constitutively expressed in endothelial cells and was detected in only 5 x 10(2) unstimulated cells and 10(2) phorbol ester-stimulated cells. Expression was increased upon stimulation with phorbol ester. With this technique, TFPI-1 mRNA in monocytes was rather low even when cells were stimulated with phorbol ester or after adhesion.

Human allogeneic lymphocytes trigger endothelial cell tissue factor expression by a tumor necrosis factor-dependent pathway

Lymphocyte adhesion to endothelial cells and the extravascular deposition of fibrin are 2 important processes during pathologic situations such as allograft rejection. Tissue factor (TF) expression was therefore measured on human umbilical vein endothelial cells (HUVECs) after coculture with allogeneic lymphocytes (PBLs) by a factor Xa generation assay. When cocultured with PBLs, HUVECs expressed strong procoagulant activity related to the TF/factor VII-dependent pathway, which was enhanced when endothelial cells were treated with interferon-gamma (IFN-gamma). The highest TF activity was measured when 10(5) lymphocytes were incubated with 10(4) HUVECs (ratio 10: 1) for 4 hours, a time-dependent course similar to that obtained with tumor necrosis factor-alpha (TNF-alpha), and direct contact between the 2 cell types was necessary. PBL-induced TF activity was inhibited by cycloheximide or actinomycin D, indicating active protein synthesis that was confirmed by the increase in TF mRNA detected by reverse transcription-polymerase chain reaction. It was then demonstrated that 1 of the primary signaling pathways leading to endothelial cell TF expression was a rapid initial interaction between membrane TNF expressed on PBLs and the 75-kd TNF receptor, with subsequent involvement of platelet-activating factor and P-selectin. Finally, we showed that the transduction of external signals involving the activation of protein kinase C and protein tyrosine kinases also contributed to the regulation of TF expression.

Human T lymphocyte proliferative response to resting porcine endothelial cells results from an HLA-restricted, IL-10-sensitive, indirect presentation pathway but also depends on endothelial-specific costimulatory factors

To investigate the mechanisms of cellular rejection in pig-to-human xenotransplantation, the proliferation of different human purified lymphocyte subpopulations in response to swine leukocyte Ag class II-negative porcine aortic endothelial cells (PAEC) was measured in the presence or absence of human autologous adherent cells (huAPC). CD8+ lymphocytes proliferated moderately in the absence of huAPC, and the immune response was slightly increased when huAPC were added. CD56+ lymphocytes failed to proliferate in response to PAEC whether huAPC were present or not. CD4+ lymphocytes alone did not proliferate in response to PAEC, but a strong proliferative response was observed in the presence of metabolically active huAPC. This response was totally abolished by mAbs directed against HLA class II molecules or by pretreatment of huAPC by human IL-10. Even in the presence of huAPC, CD4+ lymphocytes failed to respond to fixed PAEC or to PAEC-lysates, suggesting that PAEC must be viable to support lymphocyte proliferation. Finally, none of the nonendothelial porcine adherent cells tested was able to induce human lymphocyte proliferation, despite the fact that they also provided a large set of xenogeneic peptides. Our results show that the indirect presentation pathway of xenoantigens by huAPC to CD4+ lymphocytes is crucial in the response to porcine endothelial cells, and that IL-10 could be of therapeutic interest to prevent human lymphocyte activation by this pathway. Furthermore, we demonstrated that stimulatory signals specifically provided by endothelial cells are also necessary for this huAPC-restricted proliferative response.

Docosahexaenoic and eicosapentaenoic acids inhibit in vitro human endothelial cell production of interleukin-6

The interaction between lymphocytes, cytokines, and endothelial cells (EC) is a key step in the inflammatory process. Interleukin-6 (IL-6) a pleiotropic cytokine in its effects, seems to be an early indicator of acute systemic inflammation. In this study, we have examined the effects of polyunsaturated fatty acids (PUFAs) on the production of IL-6 by human unstimulated EC or EC stimulated with TNF-alpha (100 U/ml); IL-4 (100 U/ml); LPS (1 ug/ml); or allogeneic peripheral blood lymphocytes (PBL). Twenty-four hour culture supernatants of immunoreactive IL-6 were measured by Sandwich ELISA. We have shown that the production of IL-6 was potentiated when EC were stimulated with TNF-alpha; IL-4; LPS; or monocyte-depleted PBL in comparison to unstimulated EC. The addition of n-3 PUFAs in culture medium (100 ug/ml DHA or EPA) significantly reduces the production of IL-6 by unstimulated EC; or stimulated with TNF-alpha; IL-4 pg/ml); LPS or depleted PBL respectively for DHA and EPA, whereas the n-6 PUFAs (Arachidonic acid), even used at the highest concentration, was ineffective. This inhibitory effect is PUFA dose dependent but is more potent with EPA than DHA. Regardless of the mode of action, since IL-6 is known to be involved in hematopoiesis, in the regulation of the immune response and in the inflammatory reaction, these results suggest that n-3 PUFAs may play a role in suppressing inflammation. Further studies are needed to elucidate the mechanism involved and the choice between the two fatty acids for clinical and therapeutic purposes.

End stage coronary disease treated with the transmyocardial CO2 laser revascularization: a chance for the 'inoperable' patient

OBJECTIVE

The aim of this study is to evaluate the short and mid-term efficacy of the Transmyocardial High Power CO2 Laser Revascularisation (TMLR) as a last resource method for end-stage coronary disease patients.

METHOD AND PATIENTS

The High Power CO2 Laser 800 W Heart Laser (PLC Medical Systems) was used since February 1994 to treat 268 patients. In 52% of the cases (140) the indication for TMLR treatment was virtual inoperability by the classical bypass revascularisation. In the other 128 patients (48%), where only an incomplete revascularisation was expected, the TMLR was combined with a feasible bypass revascularisation (CABG). Of all patients, 71% were operated on 1-5 times before and or treated by several percutaneous transluminal coronary angioplasty (PTCA). All patients were sufferers of angina pectoris and most were classified Canadian Cardiac Society (CCS) 3-4, despite the maximal medical treatment. The ejection fraction was normal in 13% of patients only, and in 47% of them it was below 40% (10-68%).

RESULTS

The operation itself was generally well tolerated. We lost only one patient at the table. The hospital survival was 89.2%; 88.2% in the combined group and 90.3% in the TMLR only group. After the routine follow up screening 3, 6 and 12 months postoperatively (262 patients--131 TMLR and 131 TMRL/CABG), 40% of the TMLR patients upgraded into the functional class CCS 0-1; the combined group of patients scored up even in 84%. All considering their quality of life to be 'better than years ago'. The ergometry stress test, impossible for most of them before, became feasible and better in 80% of the patients. In the follow up period of the combined group, another 6 (4.7%), and in the TMLR only group, 12 (9.4%) patients died.

CONCLUSION

The short and middle term results of this--until now the largest single institution series of TMLR treated patients--were that patients almost without exception were refused for any kind of surgery by several other centres; this shows an acceptable survival rate and a surprising level of pain relief, increased activity and better quality of life then ever expected. In our experience, TMLR is a suitable method for treatment of end stage coronary disease, if all standard measures, medical therapy, PTCA and redo coronary revascularisation possibilities are exhausted. The favourable results imply the question as to whether this method will become an alternative for a second bypass operation in the future. The TMLR as an alternative for heart transplant is already a reality for some of our patients.

Docosahexaenoic and eicosapentaenoic acids inhibit in vitro human lymphocyte-endothelial cell adhesion

Dietary supplementation with fish oil, which contains high amounts of long chain omega 3 ((n-3)) polyunsaturated fatty acids (PUFAs), particularly docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), has recently been shown to have protective and ameliorative effects on diseases characterized by chronic inflammatory reactions. Interactions between vascular endothelium, mononuclear cells, and cytokines are crucial steps in the course of inflammatory processes such as chronic graft rejection. We therefore studied the effects of DHA and EPA on both the adhesion of peripheral blood lymphocytes (PBL) to human endothelial cells (EC) in culture and the expression of EC-adhesion molecules and their counterreceptors on PBL. The addition of DHA or EPA to the adhesion assay significantly decreased the adhesion of PBL to untreated EC and tumor necrosis factor-alpha (TNF alpha)-, interleukin (IL) 4-, and lipopolysaccharide-stimulated EC. When EC were pretreated with (n-3) PUFAs for 18 hr, washed, and then stimulated by TNF alpha, IL-4, or lipopolysaccharide, PBL adhesion was also significantly reduced compared with controls. We also showed that PBL preincubated with DHA or EPA, and then washed and chromium radiolabeled, still exhibited an adhesion inhibition to TNF alpha- and IL-4-treated EC as well as untreated EC. Cytofluorometry and immunoenzymatic analyses indicated that pretreatment of EC with (n-3) PUFAs before their activation significantly reduced the EC-induced expression of vascular cell adhesion molecule 1, whereas the level of expression of intercellular adhesion molecule 1 and E-selectin was not modified. Furthermore, we showed that incubation of PBL with DHA or EPA moderately reduced the level of cell surface expression of L-selectin and leukocyte function-associated antigen 1, but not of very late antigen 4. In all cases, the inhibitory effect of (n-3) PUFAs was specific and dose dependent. In addition, DHA seems to be a more potent inhibitor than EPA, but the two compounds in association had an additive effect. Regardless of the mode of action, this inhibitory effect may explain the protective and ameliorative effects of (n-3) PUFAs on diseases involving chronic inflammatory reaction.

Human lymphocyte adhesion to xenogeneic porcine endothelial cells: modulation by human TNF-alpha and involvement of VLA-4 and LFA-1

Considering that in the allogeneic situation the adhesion of recipient lymphocytes to donor endothelial cells initiates the cellular rejection, we questioned the possible occurrence of a similar process in the xenogeneic situation. The adhesion of human peripheral blood lymphocytes (PBL) to porcine aortic endothelial cells (PAEC) was thus studied in an in vitro porcine-to-human xenogeneic model. It was found that 25.9% of human PBL adhered to resting PAEC. Furthermore, this adhesion increased significantly when the PAEC were stimulated by the human cytokine TNF-alpha (tumor necrosis factor-alpha). The effect of human TNF-alpha was concentration- and time-dependent and was maximal (from 25.9% to 35.6%) with 100 U/ml during 6 h. Moreover, blocking experiments with monoclonal antibody (mAb) demonstrated the role of the PBL adhesion molecules LFA-1 and especially VLA-4. Indeed, an anti-CD11a mAb decreased PBL adhesion to resting PAEC by 17.1% and to TNF-alpha stimulated PAEC by 16.9%, whereas an anti-CD49d mAb decreased dramatically PBL adhesion to resting PAEC by 53.1% and to TNF-alpha stimulated PAEC by 41.0%. Finally, phenotypic analysis of the adherent PBL showed that 50.5% of adherent cells to resting PAEC were NK (natural killer) cells, whereas 50.7% of adherent cells to TNF-alpha stimulated PAEC were T lymphocytes, showing the preferential adhesion of NK cells to resting PAEC, and that the stimulation of the PAEC with human TNF-alpha affects predominantly T lymphocyte adhesion. These results indicate that human PBL could bind to xenogeneic PAEC and that this interaction could be a first step of a xenogeneic cellular rejection.

Human NK cell-mediated direct and IgG-dependent cytotoxicity against xenogeneic porcine endothelial cells

Once hyperacute rejection has been prevented, the pig-to-human xenograft might be exposed to vascular cell-mediated rejection directed against vascular structures. In order to evaluate the relative importance of direct and antibody-dependent anti-endothelial cell-mediated cytotoxicity in different individuals, freshly isolated human blood leukocytes were incubated with confluent porcine aortic endothelial cells (PAEC) in a 4 h Cr-release cytotoxicity assay. Peripheral blood mononuclear cells (PBMC) and lymphocytes (PBL) of all subjects tested (but not monocytes or neutrophils) directly killed PAEC, with wide interindividual variations (from 2.8% to 32%). The addition of heat-inactivated autologous serum to PBMC and PBL (but not to myeloid cells) always enhanced cytotoxicity. This antibody-dependent cell-mediated cytotoxicity (ADCC) was also observed in the presence of adult pooled serum and cord blood pooled serum and was eliminated after adsorption of adult pooled serum to insoluble protein A, demonstrating that IgG is the only class of immunoglobulin involved in this phenomenon. Moreover, blocking Fc gamma RIII with an anti-CD16 mAb eliminated ADCC without affecting direct cytotoxicity. When the ADCC exerted by the PBL of all subjects was assessed with the same preparation of purified IgG, wide interindividual variations were again observed. Surprisingly, there was no correlation between direct cytotoxicity and ADCC although, as depletion experiments demonstrated, both were due to CD16+ natural killer (NK) cells. These results argue that CD16+ NK cells could play an important role in early vascular rejection of porcine discordant xenografts, by both a direct and an IgG xenoreactive natural antibody-dependent cell-mediated cytotoxicity.

Evolution of blood coagulation activators and inhibitors in the healthy human fetus

Blood coagulation proteins were determined in 285 healthy fetuses from 19 to 38 weeks' gestation and compared with those of 60 normal full-term newborns and 40 adult controls. Prolongation of the coagulation screening tests, prothrombin time, activated partial prothrombin time, and thrombin clotting time, in fetuses throughout intrauterine life was explained by low levels of vitamin K-dependent factors (II, VII, IX, and X), contact factors (XI, XII, prekallikrein, and high-molecular-weight kininogen), factor V, factor VIII, and fibrinogen. Low levels of antithrombin III, heparin cofactor II, protein C and protein S, and tissue factor pathway inhibitor were also found, and these probably contributed to a satisfactory hemostatic balance. Some of these parameters were evaluated by both immunologic and functional assays to detect possible "fetal" proteins. An increase in factor levels was observed after the thirty-fourth week of intrauterine life for most of the coagulation activators and inhibitors, but only factors V and VIII reached adult values at birth. This study therefore showed that fetal hemostasis is a dynamic system that evolves gradually toward the neonatal state and then toward the adult state.

Removal of terminal alpha-galactosyl residues from xenogeneic porcine endothelial cells. Decrease in complement-mediated cytotoxicity but persistence of IgG1-mediated antibody-dependent cell-mediated cytotoxicity

To determine the role of the terminal alpha-galactosyl residue in the endothelial damage mediated by human xenoreactive natural antibodies (IgM and IgG), we treated porcine endothelial cells in culture with green coffee bean alpha-galactosidase. A practically complete removal of terminal alpha-Gal residues (as evaluated by flow cytometry with Bandeiraea simplicifolia isolectin B4) and concomitant exposure of N-acetyllactosamine were obtained without altering cell viability. A dramatic decrease in IgM and IgG binding (from a pool of human sera) was observed, confirming the key role of the alpha-galactosyl residues. The enzyme treatment did not induce any nonspecific immunoglobulin binding sites, but led to the exposure of new epitopes for a minor fraction of IgM. The main residual IgM and IgG binding could be due to xenoantigens other than the alpha-galactosyl residues. When alpha-galactosidase-treated endothelial cells were used as targets in cytotoxicity experiments, they were less susceptible than untreated cells to complement-mediated cytotoxicity induced by fresh human serum. In contrast, they did not acquire resistance to human IgG-dependent cellular cytotoxicity, despite the decrease in IgG binding. Because it is known that antibody-dependent cytotoxicity mediated by CD16+ NK cells is dependent on IgG1 and IgG3, and not on IgG2 or IgG4, which was confirmed by blocking experiments, we studied the binding of all four subclasses to intact and alpha-galactosidase-treated endothelial cells. Two major subclasses, IgG1 and IgG2, bound to untreated endothelial cells, whereas IgG3 binding was low and IgG4 binding was negligible. A decrease in IgG1, IgG2, and IgG3 binding was observed upon alpha-galactosidase treatment, indicating that antibodies belonging to these three subclasses recognize alpha-galactosyl residues. The decrease in IgG2 binding was more pronounced than the decrease in IgG1 binding. Collectively, these data indicate that IgG1 xenoreactive natural antibodies, including those which are not directed at the alpha-galactosyl residues, could play a major role in the early delayed vascular rejection of pig xenografts.

Docosahexaenoic and eicosapentaenoic acids inhibit human lymphoproliferative responses in vitro but not the expression of T cell surface activation markers

The effects of polyunsaturated fatty acids (PUFAs: docosahexaenoic (DHA) and eicosapentaenoic (EPA) acids) on induced lymphocyte proliferation and expression of CD25alpha chain of interleukin-2 receptor, CD71 and HLA-DR were investigated. PUFAs had no effect on phytohaemagglutinin (PHA)-induced lymphocyte agglutination, but they strongly inhibited the lymphoproliferative response to PHA. This inhibitory effect is PUFA dose-dependent and seems to be more potent with DHA than EPA, Pre-incubation experiments showed that lymphocytes cultured with PUFAs for 6 h then washed and exposed to PHA, still inhibited lymphocyte proliferation. The authors also showed that this inhibitory activity was time dependent but became nonsignificant when PUFAs were added after 48 h lymphocyte culture. The addition of excess exogenous human recombinant rIL-2 partly restored PHA-lymphocyte proliferation inhibited by EPA but not by DHA. On the other hand, the authors showed that PUFAS did not inhibit IL-2 stimulated lymphocyte proliferation. The addition of PUFAs to cell culture medium had no inhibitory action on the PHA-induced lymphocyte expression of CD25, CD71 and HLA-DR. Furthermore, this effect appeared independent of eicosanoid synthesis or peroxide formation. Indeed, the inclusion of aspirin and vitamin E in the culture medium did not prevent the inhibitory effects of PUFAs on lymphocyte proliferation. Regardless of the mechanism of action, the inhibitory effect of PUFAs on activated lymphocytes may explain why some clinical trials of fish oil supplemented diets containing high amounts of DHA and EPA have been successful in improving the health status of patients suffering from inflammatory and autoimmune disorders.

A simplified and low-cost one-stage chromogenic assay for tissue factor dependent procoagulant activity of endothelial cells

We developed a sensitive tissue factor (TF) chromogenic assay on a limited number of endothelial cells (EC), performed in microtiter plates, and which uses a normal pooled human plasma instead of purified concentrates as a source of coagulation factors. Primary cultures of human umbilical vein EC (HUVEC), both unstimulated and stimulated by lipopolysaccharide (LPS) were incubated with 50 microliters of of diluted normal human plasma (NHP) and 50 microliters of Factor Xa-specific chromogenic substrate (CBS 31-39, Stago, France). Hirudin was added at 4 U/ml to the plasma/CBS 31-39 mixture to inhibit thrombin generation. Optical densities were read at 405 nm and corresponding amounts of generated factor Xa were expressed in mU Xa/well using a standard curve established with purified human Factor Xa. The following parameters were then defined: the number of EC to plate (10(4) EC/well of a 96-well plate), the plasma-test dilution (1:20), the concentration of CBS 31-39 (0.50 mM) and the incubation time of reagents with EC (2 hours). The procoagulant activity (PCA) measured was only dependent on TF since it was no longer detectable either when FVII-deficient plasma was tested instead of normal human plasma or when PCA assays were performed in the presence of a blocking anti-human TF monoclonal antibody. This method allowed detection of a TF-dependent PCA on as few as 1000 EC per well. In addition, TF expression equal to 50% of maximal values was measured with LPS concentrations as low as 1 ng/ml, supporting the high sensitivity of the assay.

Compared TCR and CD3 epsilon expression on alpha beta and gamma delta T cells. Evidence for the association of two TCR heterodimers with three CD3 epsilon chains in the TCR/CD3 complex

Current models for TCR/CD3 complex stoichiometry involve one or alternatively two TCR heterodimer(s) associated with two CD3 epsilon per complex. They mainly constructed on the basis of biochemical studies involving disruption of membrane complexes. The present study was undertaken to quantify the relative proportions of CD3 epsilon and TCR chains on alpha beta and gamma delta lymphocytes in nondenaturing conditions. Quantitative flow cytometry revealed that alpha beta and gamma delta PBL express on an average 1.56 and 1.52 more CD3 epsilon-chain than beta- and delta-chains, respectively. Accordingly, CD3 epsilon to TCR-alpha, TCR-beta, TCR-gamma, and TCR-delta ratios found on three polyclonal cell lines and on Jurkat cells were all very close to 1.50. These results clearly demonstrate that alpha beta as well as gamma delta T cells express approximately 1.50 more CD3 epsilon-chain than each of the TCR chains. They strongly suggest that alpha beta and gamma delta TCR/CD3 complexes involve two TCR heterodimers associated with three CD3 epsilon-chains (or a multiple of this combination). In addition, our results showed that gamma delta PBL expressed about 1.90 more TCR (-delta vs -beta) and CD3 epsilon-chains than alpha beta PBL. Furthermore, TCR-beta expression and CD3 epsilon expression were higher on CD4+ alpha beta PBL than on CD8+ alpha beta PBL, whereas TCR-delta expression and CD3 epsilon expression were both identical on CD8+ gamma delta PBL and on CD8- gamma delta PBL. These results demonstrate that CD8+ or CD8- gamma delta PBL, CD4+ alpha beta PBL and CD8+ alpha beta PBL express decreasing levels of the TCR/CD3 complex.

Compared TCR and CD3 epsilon expression on alpha beta and gamma delta T cells. Evidence for the association of two TCR heterodimers with three CD3 epsilon chains in the TCR/CD3 complex

Current models for TCR/CD3 complex stoichiometry involve one or alternatively two TCR heterodimer(s) associated with two CD3 epsilon per complex. They mainly constructed on the basis of biochemical studies involving disruption of membrane complexes. The present study was undertaken to quantify the relative proportions of CD3 epsilon and TCR chains on alpha beta and gamma delta lymphocytes in nondenaturing conditions. Quantitative flow cytometry revealed that alpha beta and gamma delta PBL express on an average 1.56 and 1.52 more CD3 epsilon-chain than beta- and delta-chains, respectively. Accordingly, CD3 epsilon to TCR-alpha, TCR-beta, TCR-gamma, and TCR-delta ratios found on three polyclonal cell lines and on Jurkat cells were all very close to 1.50. These results clearly demonstrate that alpha beta as well as gamma delta T cells express approximately 1.50 more CD3 epsilon-chain than each of the TCR chains. They strongly suggest that alpha beta and gamma delta TCR/CD3 complexes involve two TCR heterodimers associated with three CD3 epsilon-chains (or a multiple of this combination). In addition, our results showed that gamma delta PBL expressed about 1.90 more TCR (-delta vs -beta) and CD3 epsilon-chains than alpha beta PBL. Furthermore, TCR-beta expression and CD3 epsilon expression were higher on CD4+ alpha beta PBL than on CD8+ alpha beta PBL, whereas TCR-delta expression and CD3 epsilon expression were both identical on CD8+ gamma delta PBL and on CD8- gamma delta PBL. These results demonstrate that CD8+ or CD8- gamma delta PBL, CD4+ alpha beta PBL and CD8+ alpha beta PBL express decreasing levels of the TCR/CD3 complex.

Evidence of noninvolvement of swine MHC class II in the in vitro proliferative response of human lymphocytes to porcine endothelial cells

Successful pig-to-human xenotransplantation may expose swine endothelium to the human immune system. Since endothelial MHC class II expression is crucial in the genesis of an allogeneic lymphocyte response, the involvement of porcine MHC (SLA) class II molecules in the induction of human lymphocyte proliferation was studied. When cocultured with a confluent monolayer of irradiated porcine aortic endothelial cells (PAEC), human peripheral blood mononuclear cells (PBMC) incorporated tritiated thymidine. Monocyte depletion strongly reduced the magnitude of the lymphocyte proliferative response. Resting cultured PAEC were SLA class II-negative and an induction of these molecules during the xenogeneic mixed lymphocyte endothelial cell culture (XMLEC) was not observed. Moreover, the addition of an antibody directed against the SLA-DR molecule was without effect. Lymphocyte proliferation was also studied in response to SLA class II-positive stimulating cells--either human TNF-alpha-stimulated PAEC or porcine splenocytes. Induction of SLA class II molecules on PAEC had no effect on the human PBMC proliferative response. Moreover, human PBMC did not proliferate in response to porcine splenocytes. These results suggest (1) that SLA class II molecules are not involved in the induction of the human lymphocyte proliferative response and (2) that the endothelial nature of the stimulating cells plays a key role in this proliferation.

Inhibition of induced lymphocyte proliferation by lipid and protein components of the syncytiotrophoblast plasma membrane

PROBLEM

The aim of this work was to define the respective responsibilities of the lipid and protein components of syncytiotrophoblast plasma membranes on the inhibition of lymphocyte proliferation induced in vitro.

METHOD

A fractionation method using octyl-beta-D-glucopyranoside enabled lipoprotein, lipid, and protein fractions to be isolated from the membrane.

RESULTS

The lipid fraction was shown nonspecifically to inhibit lymphocyte proliferation, to a lower extent compared with the native membrane. Alternatively, the protein fraction used as a proteoliposome contained the totality of the cytostatic effect of the native fraction.

CONCLUSION

These results are discussed generally in the context of the immunoregulatory role of membrane lipids and proteins and in relation to the local properties of syncytiotrophoblast plasma membrane components in fetal graft tolerance.

Tissue factor activity of syncytiotrophoblast plasma membranes and tumoral trophoblast cells in culture

During pregnancy, important modifications of hemostasis occur resulting in mothers in hypercoagulability and the role of placental cells such as trophoblast cells has been hypothesized. In this study, we first showed that syncytiotrophoblast plasma membranes, isolated from normal human placenta, expressed a strong tissue factor (TF) activity. We then studied TF activity of two continuous trophoblast cell lines (JEG-3 and BeWo) in comparison to human umbilical vein endothelial cells (HUVEC) and transformed human endothelial cells (ECV-304). TF assays were performed on intact detached confluent cells. Unstimulated JEG-3 and BeWo cells exhibited a very high TF activity which slightly increased after 2 to 4 h TNF-alpha stimulation. In contrast, HUVEC and ECV-304 had a lower basal TF activity which was mainly inducible by TNF-alpha, with a maximum effect after 4 to 6 h stimulation. For both cell types, TF activity was decreased to basal value after 16-hour TNF-alpha stimulation. These results support that trophoblast cells are able to express TF but the involvement of this property in the hemostatic physiological changes observed during pregnancy, remains to be demonstrated.

Preferential use of dilutions of single sera than mixture of sera to standardize the quantitation of anticardiolipin antibodies

The aim of this study was to compare four house standards coming from two University Hospital laboratories with the standards provided by the Antiphospholipid Standardization Laboratory (ASL) in order to quantify anticardiolipin antibodies. Using two different plates and two different buffered protein solutions, slopes from the serial dilutions of each of the four house standards were found comparable. In contrast different slopes were obtained when using the ASL standards which consist of a mixture of sera. Our results indicate that dilutions of single sera are more suitable than mixture of sera when quantification of anticardiolipin antibodies is required.

IL-4, but not tumor necrosis factor-alpha, increases endothelial cell adhesiveness for lymphocytes by activating a cAMP-dependent pathway

IL-4 and TNF-alpha increase endothelial cell adhesiveness for PBL by promoting the expression of adhesion molecules. We investigated the intracellular cAMP involvement in the increased endothelial cell adhesivity induced by IL-4 or TNF-alpha. We showed that both IL-4 and TNF-alpha increased intracellular cAMP in endothelial cells (EC). Furthermore, dibutyryl-cAMP and forskolin (which increased intracellular cAMP) increased basic EC adhesivity for PBL. The co-stimulation of EC with cAMP elevating agents and TNF-alpha, but not IL-4, resulted in an additive increase in EC adhesiveness. 2',5' dideoxyadenosine, an inhibitor of adenylate cyclase, decreased PBL adhesion to IL-4- but not TNF-alpha-treated EC. Similarly, HA1004, a protein kinase A inhibitor, totally reversed the IL-4 but not TNF-alpha effect on EC adhesiveness, whereas H7, a protein kinase C inhibitor, did not antagonise cytokine-enhanced EC adhesivity. These results indicate that IL-4, but not TNF-alpha, uses a cAMP-dependent pathway to increase PBL adhesion. Furthermore, we showed that cAMP elevation in EC did not induce vascular cell adhesion molecule 1, the only identified adhesion molecule induced by IL-4, indicating that a rise in cAMP in EC promotes an as yet unidentified adhesion pathway. Our results show that IL-4 increases EC adhesiveness for PBL through activation of protein kinase A by promoting an unidentified adhesion pathway.

IL-4, but not tumor necrosis factor-alpha, increases endothelial cell adhesiveness for lymphocytes by activating a cAMP-dependent pathway

IL-4 and TNF-alpha increase endothelial cell adhesiveness for PBL by promoting the expression of adhesion molecules. We investigated the intracellular cAMP involvement in the increased endothelial cell adhesivity induced by IL-4 or TNF-alpha. We showed that both IL-4 and TNF-alpha increased intracellular cAMP in endothelial cells (EC). Furthermore, dibutyryl-cAMP and forskolin (which increased intracellular cAMP) increased basic EC adhesivity for PBL. The co-stimulation of EC with cAMP elevating agents and TNF-alpha, but not IL-4, resulted in an additive increase in EC adhesiveness. 2',5' dideoxyadenosine, an inhibitor of adenylate cyclase, decreased PBL adhesion to IL-4- but not TNF-alpha-treated EC. Similarly, HA1004, a protein kinase A inhibitor, totally reversed the IL-4 but not TNF-alpha effect on EC adhesiveness, whereas H7, a protein kinase C inhibitor, did not antagonise cytokine-enhanced EC adhesivity. These results indicate that IL-4, but not TNF-alpha, uses a cAMP-dependent pathway to increase PBL adhesion. Furthermore, we showed that cAMP elevation in EC did not induce vascular cell adhesion molecule 1, the only identified adhesion molecule induced by IL-4, indicating that a rise in cAMP in EC promotes an as yet unidentified adhesion pathway. Our results show that IL-4 increases EC adhesiveness for PBL through activation of protein kinase A by promoting an unidentified adhesion pathway.

Complete saturation of protamine sulphate by dsDNA is necessary in order to obtain a highly sensitive and specific anti-dsDNA ELISA

A protamine sulphate (PS) pretreated solid phase coated with different amounts of dsDNA has been used to develop a sensitive, specific and reproducible anti-dsDNA ELISA. Using low concentrations of a dsDNA coat 50% of SLE sera were found to be positive and false positive reactivity due to anti-PS reactivity was found in 3/40 patients with other auto-immune diseases (OAID). In contrast, when PS was saturated with higher concentrations of dsDNA 80% of SLE sera were detected, the reproducibility of the results was better and anti-PS reactivity of OAID patients with an anti-PS reactivity disappeared. The sera of three other OAID patients contained low avidity anti-dsDNA, measured after a salt elution step in the ELISA procedure, and 2/60 patients with non-auto-immune disease exhibited a false positive anti-dsDNA reactivity since they reacted with the solid phase even in the absence of PS and dsDNA. Thus an ELISA procedure using a PS pretreated solid phase permits the sensitive, specific and reproducible measurement of anti-dsDNA antibodies only if a high concentration of dsDNA is coated on the PS and appropriate controls are performed.

Interleukin 4 and tumour necrosis factor alpha induce different adhesion pathways in endothelial cells for the binding of peripheral blood lymphocytes

We demonstrated that tumour necrosis factor alpha (TNF-alpha) and interleukin 4 (IL-4) increased endothelial cell (EC) adhesiveness for peripheral blood lymphocytes (PBL) by promoting transcription and protein synthesis. The different kinetics observed with TNF-alpha and IL-4 suggest the involvement of different adhesion molecules. Blocking adhesion assays and immunofluorescence analysis showed that PBL adhesion to endothelial cells involves different pair adhesion molecules. Whereas IL-4 promoted an LFA-1-dependent/ICAM-1-independent adhesion pathway on EC, TNF-alpha stimulated an LFA-1-dependent/ICAM-1-dependent adhesion pathway on EC. In contrast, VLA-4/VCAM-1 molecules were involved in PBL adhesion both to IL-4 and to TNF-alpha-stimulated EC. Finally, we found that a CD2-dependent/LFA-3-independent adhesion pathway was mainly involved in IL-4-stimulated EC.

Human Sertoli cells in vitro. Lactate, estradiol-17 beta and transferrin production

Human Sertoli cell parameters, namely lactate, estradiol-17 beta, and transferrin production, were determined after a 24-hour incubation with either human follicle stimulating hormone (FSH) or dbcAMP in the presence or absence of testosterone plus a phosphodiesterase inhibitor (1-methyl-3-isobutylxanthine; MIX). Testicular tissues were obtained from 10 young patients (mean age, 29 years); using a 3-step enzymatic treatment, Sertoli cell enriched preparations (> 92%) were studied after 4 days as primary cultures. No significant changes in lactate, estradiol-17 beta, and transferrin outputs have been observed according to age in patients ranging in age from 16 years to 47 years. Sertoli cell production of the compounds is controlled by testosterone plus MIX; FSH (or dbcAMP) treatment only slightly improves their synthesis. It is suggested that human Sertoli cell function, as far as the parameters measured in this study are concerned, is likely regulated by cAMP-dependent and independent pathways.