ISSN:0041-1337    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Background.To date, several single- and multicenter clinical trials have attempted to induce specific immunological unresponsiveness using donor bone marrow cell infusions to augment solid organ transplantation, but the outcomes have not been definitive.Methods.Between September 1994 and May 1998, 63 cadaver (CAD) renal transplant recipients of either one or two postoperative donor bone marrow cell (DBMC) infusions were prospectively compared with 219 non-infused controls given equivalent immunosuppression. There was at least a 1 HLA DR antigen match present between donors and recipients. The immunosuppressive regimen included a 10-day course of OKT3 induction, and tacrolimus, mycophenolate mofetil, and methylprednisolone maintenance. A total 7.01×108±1.9×108(SD) DBMC/kg was infused into the CAD recipients on either days 4 and 11 (n=42) or one half of that dose on day 4 (n=21) postoperatively. Clinical follow-up has ranged from 2.9 to 6.3 years (mean, 4.7 years). Studies were also performed of humoral immunity and quantitative cellular chimerism.Results.There is clear-cut equivalence in immunosuppressive dosaging and in the other major demographic variables in both groups. However, only 2/63 DBMC recipients had biopsy-proven chronic rejection, whereas 41/219 showed chronic rejection in the controls (P=<0.01). In both groups, mortality was not associated with rejection. The actuarial graft survival at 6.3 years in the CAD DBMC group was 84.3% compared with 72.2% in the control group (not statistically significant). However, if death with a functioning graft was excluded, graft survival was 94.1% in the DBMC group and 79.8% in the controls (P=0.039). Forty patients in the control group continue to have deteriorating renal function (increasing serum creatinine concentrations to 2 mg/dl and higher), compared with 2 patients in the DBMC group (P=0.04). In the DBMC group, chimerism in iliac crest marrow aspirates has increased 3-fold in yearly sequential measurements between 1 and 4 years postoperatively averaging 1.3±0.36% (SE) most recently. This has not occurred in the controls.Conclusions.There now appears to be more solid long-term evidence, in kidney transplant recipients prospectively receiving DBMC infusions, of an improvement in long-term graft survival, and of the degree of chimerism positively correlating with the absence of graft loss.

ISSN:0041-1337    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Background.The Rel/NF-&kgr;B transcription factor pathway, regulated by I&kgr;B proteins, is considered central to immune responses, although there are surprisingly few in vivo data concerning alloresponses.Methods.We undertook analysis of NF-&kgr;B and I&kgr;B mRNA intracardiac allograft expression, and NF-&kgr;B nuclear translocation, during acute rejection versus CD154 monoclonal antibody (mAb)-induced tolerance induction in fully MHC-disparate mice.Results.Intragraft expression of all nine NF-&kgr;B and I&kgr;B genes increased during development of rejection, and nuclear translocation of p50, p52, and p65 was detected. CD154 mAb therapy decreased mRNA levels of all nine NF-&kgr;B and I&kgr;B genes, and impaired nuclear translocation of p50, p52, and p65 NF-&kgr;B proteins. However, prolonged survival could not be induced by CD154 mAb in p50- or p52-deficient allograft recipients, indicating an absolute requirement for expression of these genes in CD154 mAb-induced tolerance.Conclusions.We conclude that, whereas blanket approaches to NF-&kgr;B suppression are unlikely to be effective strategies for tolerance induction, a better understanding of the roles of individual NF-&kgr;B and I&kgr;B genes may allow development of more precise and effective therapies.

ISSN:0041-1337    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Background.How the localization of antigen to the liver, through means such as oral ingestion, induces tolerance is poorly understood.Methods.To elucidate potential mechanisms we used an adoptive transfer system wherein ova-specific T cells were infused into a syngeneic host, and antigen-specific T-cell responses after delivery of soluble antigen into the liver were monitored.Results.After infusion of antigen into the portal vein, the frequency of antigen-specific T cells in lymph nodes draining the liver was lower than the frequency in peripheral lymph nodes. These findings were the reverse of what is typically observed after subcutaneous injection of antigen with adjuvant. Infusion of antigen with adjuvant into the portal vein did not alter this pattern of antigen-specific T-cell localization; however, an increased frequency of T cells, compared with antigen alone, was observed in peripheral lymph nodes and spleen. After exposure to antigen via the portal vein, T cells isolated from lymph nodes draining the liver and challenged with antigen in vitro exhibited a diminished proliferative response compared with T cells isolated from nondraining lymph nodes. This hyporesponsiveness was not observed when the antigen was administered with adjuvant.Conclusions.Our findings suggest that the influence of the liver on immune responses might reflect two processes: (1) loss of antigen-specific T cells after primary antigen injection, and (2) hyporesponsiveness on reexposure to antigen. These mechanisms may contribute to the prevention of undesirable immune responses to foods and enteric bacteria in the gastrointestinal tract. Furthermore, these results underscore the importance of minimizing inflammation in circumstances such as islet transplantation, if endogenous mechanisms of tolerance induction are to be maximized.

ISSN:0041-1337    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Background.Although transplantation of musculoskeletal allografts in humans is technically feasible, the adverse effects of long-term immunosuppression subject the patient to high risks for correcting a non-life-threatening condition. Achieving immunologic tolerance to musculoskeletal allografts, without the need for chronic immunosuppression, could expand the clinical application of limb tissue allografting. Tolerance to musculoskeletal allografts has been accomplished previously in miniature swine in our laboratory. Although stable, mixed chimerism has been suggested as the mechanism underlying long-term tolerance in a rat limb model, the mechanism of this tolerance induction has not been established. This report explores the possible relationship between hematopoietic chimerism and tolerance to musculoskeletal allografts in swine.Methods.Twelve miniature swine underwent vascularized musculoskeletal allograft transplantation from histocompatibility complex (MHC) matched, minor antigen-mismatched donors. Eight animals received a 12-day course of cyclosporine, one of which was excluded due to subtherapeutic levels. Four recipients were not immunosuppressed. Serial biopsies to assess graft viability and flow cytometry to assess chimerism were performed. Donor and third-party skin grafts were placed on recipients with surviving allografts greater than 100 days to validate tolerance.Results.Both groups developed early peripheral chimerism, but this chimerism became undetectable by postoperative day 19 in the cyclosporine group and by day 13 in the control group. Animals receiving cyclosporine developed permanent tolerance to their allografts, whereas those not receiving cyclosporine rejected their allografts in 6–9 weeks. Animals demonstrating tolerance to their bone allografts also demonstrated prolonged donor skin graft survival.Conclusions.Induction of tolerance to musculoskeletal allografts can be achieved in the MHC matched swine. Although hematopoietic chimerism is present in the immediate postoperative period, persistent, long-term chimerism does not seem to be necessary for maintenance of such tolerance.

ISSN:0041-1337    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Background.There is substantial evidence to link early graft loss after islet transplantation to isolation-induced islet cell apoptosis. Measurement of caspase 3 activity and detection of the lost cell membrane asymmetry, revealed by annexin V binding, are newly available assays that allow the analysis of early events of apoptosis.Methods.In this study, we compared these tests with the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) assay and analysis of DNA fragmentation after gel electrophoresis in freshly isolated islets obtained from rats, before and after treatment with interleukin-1 &bgr;, interferon &ggr;, and tumor necrosis factor &agr;, cytokines known to induce islet cell damage.Results.A measurable level of apoptosis was observed the day after isolation when caspase 3 activity and annexin V binding were used as assays, although no substantial DNA fragmentation was detected with TUNEL assay and DNA gel electrophoresis. Baseline caspase 3 activity was 0.8±0.3 U/100 islet equivalents and it increased to 1.4±0.45 U/100 islet equivalents 3 hr after cytokine stimulation (P<0.05 vs. unstimulated islets). The baseline level of apoptosis, as detected by annexin V binding, was 21.1%±5.8%, and it increased to 27.5%±8.1% 6 hr after addition of the cytokine cocktail (P<0.01 vs. unstimulated islets). An increase in the number of TUNEL-positive nuclei was detected 24 hr after stimulation and peaked at 48 hr. DNA laddering was also evident 24 hr after cytokine treatment.Conclusion.These data suggest that measurement of caspase 3 activity and annexin V binding analysis might represent reliable markers of early events of islet cell apoptosis.

ISSN:0041-1337    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Background.The protective effect of heat preconditioning of the liver against ischemia-reperfusion injury has been reported mostly in models of transient ischemia in relation to heat shock protein 70 (HSP70). We estimated the effect of heat preconditioning of liver grafts on the transplant survival rate and on apoptosis of sinusoidal endothelial cells (SEC) as well as hepatocytes in a rat model of liver transplantation.Methods.Donor rats of the heat shock (HS) group were subjected to heat preconditioning 48 hr before graft harvest, and HSP70 levels were estimated by Western blot analysis and immunohistochemistry. The liver isografts from the HS group and control (C) group were preserved in Euro-Collins solution for 6 or 8 hr and transplanted orthotopically. Serum hyaluronic acid and alanine aminotransferase were measured, and apoptosis of the SEC and hepatocytes was analyzed by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling staining and electron microscopy.Results.HSP70 expression was detected not only in hepatocytes but also in SEC. In the 8-hr preservation model, the 1-week survival rate was 60% in the HS group and 0% in the C group. Serum hyaluronic acid and alanine aminotransferase levels in the HS group were significantly lower than those in the C group at 3 hr after reperfusion, and the number of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling–positive SEC in the C group (35.2%) was markedly increased compared with the HS group (10.1%). Electron microscopic examination confirmed the features of apoptosis of SEC.Conclusions.Heat preconditioning of the graft improved the survival rate of the liver transplants. Induction of HSP70 in SEC as well as in hepatocytes might attenuate preservation-reperfusion injury by inhibiting apoptosis of SEC.

ISSN:0041-1337    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Background.Previous studies showed that graft rejection is often associated with the presence of primed cytotoxic T cells (CTLs) with a high avidity for donor cells. Similar high avidity CTLs have been found in individuals who have formed IgG anti-HLA antibodies. The presence of such CTLs to a specific HLA mismatch is therefore considered to be a reflection of an activated immune system, and a contraindication for retransplantation with a donor sharing this particular HLA class I mismatch.Methods.In our study we investigated whether patients have always primed CTLs against all individual HLA class I mismatches present on a rejected graft. Therefore, 14 patients who had undergone transplantectomy after irreversible kidney graft rejection were analyzed with respect to donor-specific CTLp frequencies and the presence or absence of high avidity CTLs directed against HLA class I mismatches present on the rejected graft.Results.Patients, who have not formed anti-HLA antibodies against the donor have mainly naive CTLs. Most of the patients, that have developed IgG anti-HLA antibodies against a donor mismatch, have primed CTLs directed against that particular mismatch. However, patients with IgM anti-HLA antibodies only, and patients with IgG anti-HLA antibodies in historical sera but no IgG anti-HLA antibodies in current sera, have mainly naive CTLs against the donor HLA mismatch.Conclusion.Our results suggest that it is not always necessary to exclude repeated HLA class I mismatches for a subsequent transplantation. In addition to good anti-HLA antibody screening, the CTLp-assay may be a useful tool for donor-selection in retransplant candidates.

ISSN:0041-1337    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Background.Cadaveric kidneys experiencing longer cold ischemia time (CIT) are associated with higher levels of delayed graft function, acute rejection, and early graft loss. One mechanism to explain these results is that ischemia/reperfusion (I/R) injury makes the allograft more immunogenic by upregulating molecules involved in the immune response (e.g., HLA Class I/II).Methods.We evaluated the influence of CIT on the production of HLA Class I antibody level, measured by an antihuman globulin panel reactive antibody (AHG PRA) level, in 90 unsensitized recipients of primary cadaveric renal transplants (from a total of 1442 between 1985 and 1997) who rejected their kidneys.Results.By multivariate analysis, a CIT of 15 hr or more (vs.<15 hr) independently increased the risk of the AHG Class I PRA level being ≥20% after unsensitized patients rejected their first kidneys (relative risk=3.57; 95% confidence interval=1.26 to 10.14;P=0.01), despite the same degree of Class I/II mismatch between the two CIT groups. The overall mean peak PRA level after primary kidney rejection was significantly lower for the CIT<15 hr group (25.9%±33.9; n=24) compared with the CIT≥15 hr group (46.3%±36.5; n=66) (P<0.001).Conclusion.Longer CIT induces a humorally more immunogenic kidney.

ISSN:0041-1337    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Background.Cidofovir (CDV) is a nucleotide analogue with proven in vitro effects against cytomegalovirus (CMV) and adenovirus and has been successfully used in the treatment of CMV retinitis in AIDS patients.Methods.We performed a prospective study to evaluate the efficacy of CDV in 17 patients with hematological malignancies after allogeneic blood stem cell transplantation from related (n=3) and unrelated (n=14) donors. Dose-reduced conditioning (DRC) regimen consisted of busulfan (Bu)/fludarabine (Flu) (n=9) and idarubicin/cytosine arabinoside/Flu (n=1). Myeloablative conditioning (MC) was performed with Bu/cyclophosphamide (Cy)/etoposide (Eto) (n=4), Bu/Cy (n=2), and total body irradiation (TBI)/Cy/Eto (n=1). Antithymocyte globulin (ATG) was used in seven patients with DRC and in six patients with MC. In all patients, either the donor, host, or both were CMV IgG positive pretransplant. Indication for therapy was preemptive treatment of primary CMV antigenemia defined as two consecutive positive tests of pp65 antigenemia assay after transplant. In case of response with a decreasing number of pp65-positive leukocytes, CDV was scheduled in a dosage of 5 mg/kg body weight once a week for 2 weeks followed by maintenance therapy every 2 weeks in an outpatient setting. All patients received probenecid and prehydration as recommended. Patients were monitored using an immunostaining assay for pp65 antigen and a qualitative and quantitative CMV polymerase chain reaction (PCR). Success of treatment was defined as negativity for the pp65 antigen.Results.After DRC, nine of ten patients (90%) showed a response with seven of nine revealing a complete clearance of the virus (pp65 negative, qualitative PCR negative). In the remaining two responders, treatment was changed to ganciclovir because of either renal impairment or slow clearance of antigenemia. Only one of seven patients in the MC group experienced a temporary clearance of pp65 antigen. After MC, two patients experienced CMV disease. Treatment-related toxicity rate was moderate with four patients developing reversible renal impairment (creatinine 133–180 &mgr;mol/L); one patient with proteinuria and three patients with complaints of nausea and vomiting.Conclusion.Our data suggest the feasibility of CDV administration in patients after allogeneic transplantation. In the recommended dose, it might be used successfully for low-risk patients, e.g., after DRC or organ transplantation, in an outpatient setting.

ISSN:0041-1337    

出版商:OVID    

年代:2001

数据来源: OVID