Background. Genetic factors other than HLA have been reported to be associated with the outcome of organ transplantations. Because binding of FasL to its receptor Fas could play an important role in ...tubulitis and in the death of graft tubular epithelial cells during kidney allograft rejection, a gene polymorphism recently identified in position –671 in the promoter of the TNFRSF6 gene coding for Fas was investigated in donors. Methods. A case-control study was performed within a cohort of non-hyperimmunized adult patients who had received cadaveric kidney transplants based on the occurrence or absence of acute cellular rejection in the first 6 months after renal transplantation. Each recipient from the acute rejection group (n = 35) was matched for age (± 5 years) and number of HLA-DR mismatches with two recipients within the non-acute rejection group (n = 70). Results. The TNFRSF6-GG genotype was more frequent in donors in the group without rejection episodes. In contrast, patients who received a kidney from a TNFRSF6-A carrier were more likely to experience acute rejection episodes (relative risk nearly 2.1). Conclusion. This study suggests that donor TNFRSF6 polymorphism directly or indirectly influences acute kidney rejection episodes.
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.
: Background: In the multicenter, open‐label Myriade study, renal transplant patients were randomized to early cyclosporine microemulsion (CsA‐ME, day 0) or delayed CsA‐ME (day 6) with ...enteric‐coated mycophenolate sodium (EC‐MPS), steroids and interleukin‐2 receptor induction. One‐yr results have been published previously. We now report the results of an extension study in which patients were followed up for a period of three yr post‐transplant.
Methods: All patients completing the one‐yr core study on‐treatment were eligible to enter the extension study.
Results: Of the 203 patients, 153 completed the core trial on‐treatment; 144 (94%) entered the extension study with a minimum follow‐up of one yr (73 early CsA‐ME, 71 delayed CsA‐ME). In 75% of patients receiving EC‐MPS during the extension, the recommended dose was administered (1440 mg/d). Median creatinine clearance remained constant (57 mL/min) at 12, 24 and 30 months post‐transplant and was similar in the early and delayed CsA‐ME groups as well as in subpopulations with or without delayed graft function. One patient in the early CsA‐ME group died. No grafts were lost. The incidence of BPAR from time of transplant to the end of the extension study was 17% (24/139). Seven patients (5%) discontinued the extension study prematurely because of adverse events.
Conclusion: These results suggest that a regimen of CsA‐ME, EC‐MPS and steroids results in excellent survival rates with stable renal function over a mean follow‐up of 30 months. Immediate introduction of CsA‐ME has no deleterious effect on long‐term renal function, even among patients with delayed graft function.
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-α) 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-α stimulated endothelial cells and 5.10
2 monocytes stimulated by endotoxin. TF mRNA expression was increased by TNF-α 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 5.10
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.
Graft endothelium has a key role in organ transplantation because it regulates graft infiltration by allogeneic activated T cells. Overexpression of death molecules that could induce apoptosis of ...alloreactive T cells might be an alternative to the immunosuppressive treatment currently used in graft transplantation. Several studies have shown that immune-privileged sites express Fas ligand (FasL) and induce apoptosis of activated T-cells. We propose that endothelial cells engineered to express FasL could inhibit alloreactive T cell-proliferation by inducing apoptosis. An expression vector was constructed with human FasL cDNA and used to transfect an endothelial cell line (ECV304 cells). We demonstrated that FasL-transfected ECV304 cells were effective in inducing apoptosis of Jurkat T cell lymphoma as an agonist anti-Fas antibody. Using a mixed lymphocyte-endothelial cell culture model we observed that FasL-transfected ECV304 cells which conserved their two principal costimulatory pathways inhibited alloreactive T cell-proliferation by inducing activated T-cell apoptosis. These results suggest that endothelial cells could be interesting candidates to convey a death signal and induce hyporesponsiveness of alloreactive T cells during organ transplantation.
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.
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-α (tumor necrosis factor-α). The effect of human TNF-α 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-CDl 1a mAb decreased PBL adhesion to resting PAEC by 17.1% and to TNF-α stimulated PAEC by 16.9%, whereas an anti-CD49d mAb decreased dramatically PBL adhesion to resting PAEC by 53.1% and to TNF-α 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-α 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-α 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 xenogeneic cellular rejection.
PDF
