摘要:

Background.Protocols that incorporate donor-specific cell infusions using bone marrow, spleen, or blood transfusion continue to enhance allograft survival and often lead to tolerance in experimental models. Clinical benefits from these modalities have not been as striking, leading to ongoing study in this field. We have explored culture techniques for the in vitro selection and development of cellular effectors capable of enhancing allograft survival.Methods.Rat bone marrow or spleen cells cultured under a variety of conditions were screened for suppressor function. Bone marrow cells, nonadherent to plastic, cultured for 7 days with granulocyte-macrophage colony-stimulating factor, lipopolysaccharide, and with or without splenocytes were found to contain predominantly myeloid lineage cells and had the ability to suppress phytohemagglutinin or mixed lymphocyte reaction-induced splenocyte proliferation. Standard donor-specific peripheral blood transfusion was compared with cultured donor-specific bone marrow cells, splenocytes, or marrow cells cultured with splenocytes (cocultured) administered intravenously at 1×107cells/kg the day before an ACI to Lewis heterotopic heart transplant. Cyclosporine was administered at 10 mg/kg on day -1 and 2.5 mg/kg on days 0-6 relative to transplantation.Results.Mean allograft survival in cyclosporine-treated animals was 8.5 days without and 16.6 days with a donor-specific blood transfusion. Cocultured cells extended allograft survival (39.5 days), whereas bone marrow or splenocytes cultured alone did not. With Percoll gradient separation, two predominant culture subfractions, one with potent suppressor function and another with stimulator function, were identified. Flow cytometric analysis showed mixed populations enriched for macrophages but also including dendritic cells in both subfractions. The suppressive fraction extended allograft survival to 20.8 days and the stimulatory fraction was less effective, yet remixing of both fractions regained the full allograft survival advantage.Conclusions.In this model, the coculture of bone marrow cells and splenocytes with granulocyte-macrophage colony-stimulating factor and lipopolysac-charide produced functionally divergent subpopulations that synergistically enhanced allograft survival. The development of cellular effectors with enhanced ability to prolong allograft survival using in vitro culture techniques is possible, and provides a new therapeutic option in the use of cell infusion-based therapies.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

A major challenge in clinical transplantation today is to design a practical and effective protocol for tolerance induction compatible with cadaver organ transplantation. A preclinical rhesus monkey kidney allograft model using immediate peritransplant anti-CD3 immunotoxin (anti-CD3-IT) and donor bone marrow (DBM) is shown here to induce operational tolerance with prolonged graft survival in the absence of chronic immunosuppressive drugs. Bone marrow harvested from the kidney donor was depleted of mature alloantigen-presenting cells and T cells by removing DRbrightcells and CD3brightcells, respectively. In out-bred, major histocompatibility complex-incompatible donor-recipient pairs with high pretransplant mixed lymphocyte response and cytotoxic T lymphocyte precursor activity, four of six allografts survived for periods of 120 days to >1.5 years. Graft acceptance after peritransplant treatment followed robust elimination of both peripheral blood T cells and lymph node T cells. In most recipients given anti-CD3-IT and DBM infusion, anti-donor immunoglobulin G responses were completely inhibited. Microchimerism was observed in all recipients studied, including those not given DBM, but levels of microchimerism did not cor-relate with graft survival. Anti-CD3-IT induction in combination with modified DBM protocols such as the depletion of mature T cells and DRbrightantigen-presenting cells may offer new opportunities to improve clinical tolerance protocols beyond those attempted in the clinic to date. Overall, these results with anti-CD3-IT show promise for development of cadaver transplant tolerance induction.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Portal venous transfusions (PVTs) of blood have been shown to induce significant immunosuppression in animal models of organ transplantation. A proposed mechanism of PVT-induced immunosuppression is via alteration of Kupffer cell arachidonic acid metabolism with increased secretion of the suppressive metabolite prostaglandin E2(PGE2). This study assessed the hypothesis that PVT increases Kupffer cell PGE2production via up-regulation of Kupffer cell phospholipase A2(PLA2) as well as constitutive (COX1) and inducible (COX2) cyclooxygenase. Kupffer cells from Lewis rats were harvested 1 hr after PVT with either 1 ml of Wistar-Furth blood, systemic transfusion (SVT), or saline via portal vein (PVSal). After lipopolysaccharide stimulation, 24-hr Kupffer cell supernatant fractions were assayed for PGE2. PGE2was increased after SVT (1465±234 pg/ml) compared with PVSal (597±99;P<0.01). PVT increased Kupffer cell PGE2(5370±533;P<0.001 vs. SVT and vs. PVSal) even more substantially. Kupffer cells from PVT-treated rats were then cultured in the presence of inhibitors of PLA2, COX1, or COX2. When Kupffer cells were treated with mepacrine to inhibit PLA2(5575±453 pg/ml), PGE2production was not different from that by PVSal-treated controls (6467±614 pg/ml), but when Kupffer cells were incubated in the presence of the COX1 inhibitor flurbiprofen (3512±407 pg/ml) or the COX2 inhibitor nimesulide (2800±830 pg/ml), production was decreased 46.7% and 56.7%, respectively, over control activity without added inhibitor. PVT also increased Kupffer cells COX1 and COX2 mRNA as measured by Northern blot. Heart transplants were then performed from Wistar-Furth donors into Lewis recipients at the time of PVT, SVT, PVSal, or PVT + indomethacin (COX1/2 inhibitor). PVT prolonged allograft survival (12.0±0.9 days) compared with PVSal (6.3±0.3;P<0.01) or SVT (6.3±0.3;P<0.04). Indomethacin shortened graft survival when given with PVT (6.5±0.3 days). In summary, PVT increased Kupffer cell PGE2production, up-regulated transcription of Kupffer cells COX1 and COX2 mRNA, and prolonged cardiac allograft survival. COX1/2 inhibition abrogated the effect of PVT. The results indicated that the immunosuppressive effect of PVT may be mediated by up-regulation of Kupffer cell COX1 and COX2. Manipulation of Kupffer cell arachidonic acid metabolism may be useful in augmentation of PVT-induced immunosuppression.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Background.Although signaling via class I MHC molecules has been shown to suppress T-cell responses, the mechanisms by which these effects are mediated have not been delineated. Studies were conducted to examine the possibility that 5H7 (a murine anti-human mAb specific for the α3 domain of human class I MHC) induces programmed cell death (PCD).Materials.Normal human T cells and lymphocyte tumor lines were used. PCD was assessed by viable cell recovery (VCR) with trypan blue, ethidium bromide/acridine orange staining, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling techniques.Results.5H7 induced growth inhibition of lymphocyte tumor cell lines as assessed by [3H]thymidine incorporation. 5H7 also induced marked reductions in VCR of lymphocyte tumors and normal human T and B cells, with the most dramatic reductions occurring in B cells and B cell-derived tumors (JY, BeVD, and 521). Reductions in tumor growth observed with 5H7 monoclonal antibody, however, were not observed with other anti-human class I MHC monoclonal antibodies, TP2599 (α3 domain specific) and W6/32 (α2/α3 domain specific). Cells treated with 5H7 demonstrated typical features of PCD including cytoplasmic vacuolization, DNA condensation, and apoptotic body formation. Reduction in VCR was augmented by anti-CD3 monoclonal antibody and was not reversed by exogenous interleukin 2. Induction of PCD was not observed with soluble 5H7 F(ab)′2fragments alone, but cross-linking of 5H7 F(ab)′2fragments by F(ab)′2fragments of human Ig-absorbed goat anti-mouse Ig partially restored PCD induction, indicating that anti-class I MHC monoclonal antibody can induce PCD in an FcR-independent system and that monoclonal antibody cross-linking is necessary for PCD induction.Conclusions.These studies provide the first evidence that class I MHC molecules mediate PCD in human T and B cells.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Background.The purpose of this study was to investigate whether phosphorus-31 magnetic resonance spectroscopy (31P-MRS) of the isolated donor liver can serve as a viability indicator with prognostic value for transplantation outcome.Methods.Forty human donor livers preserved with University of Wisconsin solution were studied shortly before transplantation. The respective spectral peak areas of the isolated donor liver were correlated with the amount of hepatocellular graft damage and liver metabolic function shortly after implantation.Results.The individual phosphomonoesters, inorganic phosphate, phosphodiesters, and nicotine adenine dinucleotide peaks were not prognostic for postoperative hepatocellular damage or liver metabolic capacity. The presence of adenosine triphosphate, however, predicts a significantly better metabolic capacity to eliminate bilirubin, to synthesize fibrinogen and antithrombin III, and to maintain a better prothrombin time after transplantation. Furthermore, this study is probably the first31P-MRS demonstration in the human liver of phosphocreatine.Conclusions.In the clinical setting described, metabolic assessment using31P-MRS did not result in a reliable noninvasive test to predict primary graft dysfunction. Study of the role of phosphocreatine in liver metabolism during cold storage is needed.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Background.Data supporting the differential activation of T helper (Th) 2 cells in transplantation acceptance/tolerance in rodents have been presented by several investigators. However, the differential activation of Th2 cells may be simply the result of allograft acceptance/tolerance induction instead of a contribution to the maintenance of grafts.Methods.Therefore, we established interleukin (IL)-4 transgenic mice under the control of a cardiac α-myosin heavy chain promotor and transplanted IL-4-expressing heart allografts into unmodified recipients to determine the actual contribution of the Th2 bias to allograft acceptance.Results.Among 16 newborn C57BL/6J (B6) mice, three were positive for the IL-4 transgene. Serum IL-4 levels of transgenic versus control B6×C3H F1mice were not statistically different. Reverse-transcriptase polymerase chain reaction showed that the transgenic B6×C3H F1mice expressed IL-4 mRNA in the heart and in the lung, whereas control mice did not express IL-4 in any organ. IL-4 mRNA expression in the transgenic but not in the control heart was also confirmed by RNAse protection assay and fluorescence in situ hybridization. The survival of IL-4 transgenic B6×C3H heart grafts heterotopically placed in C3H recipients was prolonged compared with that of nontransgenic grafts (19.0±9.1 vs. 6.8±2.2 days,P=0.003). Interferon-γ mRNA expression in IL-4 transgenic heart grafts on the fifth posttransplant day as assessed by Northern blotting was suppressed compared with that in control grafts. Reverse-transcriptase polymerase chain reaction analysis showed that IL-2 mRNA was suppressed in the IL-4 transgenic grafts compared with that in control grafts, while IL-4 mRNA was observed only in IL-4 transgenic grafts. IL-10 mRNA was detected at similar levels in both transgenic and control grafts.Conclusions.A Th2 bias may contribute to allograft acceptance in part by inducing the down-regulation of Th1 -cytokine mRNAs, but it may not be sufficient to induce indefinite graft survival.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Previous studies on pathophysiological mechanisms of chronic graft rejection demonstrated the impact of both alloresponsiveness and nonspecific immunological events on the process. To study the role of alloantigen-specific factors further, we hypothesized an acceleration of chronic graft rejection after presensitization. Chronically rejected renal allografts in the established Fischer 344 → Lewis rat model were replaced sequentially by native allografts of donor origin. Grafting of second allografts was performed 2, 4, 8, and 12 weeks after the original transplantation and followed long term. Second allografts demonstrated significantly ameliorated functional and structural alterations with few cellular infiltrates. These changes were independent from the time interval between first and second engraftment (2-12 weeks); immunosuppressive treatment after the second engraftment was not influential. The nonresponsiveness was not restricted to the second kidney allografts, as heart allografts of donor origin in these recipients also functioned indefinitely, whereas third-party grafts (Lewis × Brown Norway F1) and Fischer 344 heart grafts in untreated Lewis control rats were acutely rejected.Thus, donor-specific and tissue-nonspecific graft acceptance is achieved by second engraftment of donor-specific allografts in a model of chronic graft rejection. Those observations demonstrate the synergistic effects of alloresponsiveness and of the injured graft itself for the development of chronic graft failure.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Background.Cyclosporine (CsA)-induced acute nephrotoxicity could be reduced by prevention of parenchymal accumulation of the drug itself. The objective of this prospective study was to evaluate whether cilastatin, an inhibitor of active tubular resorption of CsA, reduces CsA-induced acute nephrotoxicity in kidney graft recipients.Methods.Sixty-nine kidney recipients with immediate graft functional recovery were randomly assigned to either the treatment group (imipenem/cilastatin, n=33) or the control group (ceftazidime, n=36). All patients followed a standard immunosuppressive regimen based on CsA and low-dose prednisone. Graft function and CsA levels were evaluated 3, 5, 10, 15, and 30 days after transplantation.Results.Compared with the control group, imipenem/cilastatin administration reduced the serum creatinine level in the first 2 weeks after transplantation, reaching a significant effect on postoperative day 10 (P<0.05). No significant differences were demonstrated between the two groups for CsA levels, patient and graft survival, and all the other examined parameters.Conclusions.Our findings support the hypothesis that cilastatin administration can reduce CsA-induced acute nephrotoxicity after kidney transplantation.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Background.It has been postulated that chimerism after transplantation might promote graft acceptance. In the present study, we prospectively assessed blood chimerism in 10 lung transplant recipients during the first posttransplant year and investigated whether chimerism was associated with an immunologically stable situation of the graft.Methods.The recipients' peripheral blood mononuclear cells were obtained before transplantation and at various time points during the first postoperative year. Donor cells were detected using nested polymerase chain reaction amplification of a donor-specific HLA-DRB1 allele. Clinical graft acceptance was determined by the number of rejection episodes.Results.The incidence of blood chimerism was high during the first 3 postoperative months and then decreased over time. All patients experienced at least one acute rejection episode, and three patients developed chronic rejection.Conclusion.We, thus, conclude that rejection of the lung allograft may occur in the presence of blood chimerism.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Background.The hepatitis C virus (HCV) quasispecies feature is important for HCV persistence. Most liver grafts are reinfected by HCV after liver transplantation (LTx).Methods.The degree of HCV polymorphisms during LTx was determined by single-strand conformation polymorphism (SSCP) analysis and direct sequencing of the HCV hypervariable region 1 (HVR1).Results.The number of HCV HVR1 SSCP bands in three patients decreased within 3 months after LTx as compared with before LTx. Direct sequencing of serial samples of one patient showed that the number of HVR1 polymorphic sites was lower at 1.5 months after LTx, and that the major sequence was identical to that before LTx. The number of both the HVR1 SSCP bands and the polymorphic sites after 3 months after LTx returned to a similar level as before LTx.Conclusions.Only a subset of the preexisting HCV variants replicates in the transplant liver graft. The limited immunological selective pressure within the first post-LTx period results in a homogenous HCV population that becomes more heterogenous after the first 3 months.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID