摘要:

Background.Transplant tolerance, rather than immunity, may be favored in the setting of a lower mature lymphoid mass in the recipient induced by anti-T cell agents. A novel immunosuppressive agent, FN18-CRM9, known to specifically kill T cells with great potency, was evaluated in a transplant model.Methods.In order to ablate recipient T cells, the immunotoxin FN18-CRM9 was administered to rhesus monkey recipients of MHC-mismatched renal allografts. Donor lymphocytes were injected intrathymically into some animals.Results.All monkeys with T-cell depletion by immunotoxin had prolonged allograft survival, and tolerance confirmed by skin grafting has been confirmed in five of six long-surviving recipients.Conclusions.In this clinically relevant model, profound but transient T-cell depletion by a single agent substantially promotes tolerance.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Background.The development of strategies to enhance survival of transplanted organs and to potentially lower or even discontinue immunosuppressive therapy would represent a significant advance in posttransplant patient care. The aim of this clinical trial was to determine the effect of timing and dose of peripheral donor bone marrow cell (DBMC) infusion on graft and patient survival after liver transplantation.Methods.DBMC, obtained from vertebral bodies, were administered in 101 recipients of liver allografts (OLTX). There were 107 patients for whom DBMC could not be obtained; they received OLTX alone (controls). A total of 5×108/kg DBMC were infused at day 0 (group 1; n=9); at days 0 and 11 (group 2; n=26); or at days 5 and 11 (group 3; n=26). In group 4 (n=40), patients received up to five infusions of 2×108/kg DBMC at days 5, 14, 21, 28, and 90 after OLTX.Results.When the results from patients receiving two or more DBMC infusions (groups 2, 3, and 4) are considered, both patient and graft survival were significantly improved compared with the control group (P=0.02 andP=0.01, respectively). In groups 3 and 4, 88.5% and 95% of patients were alive with mean follow-up of 536 and 265 days, respectively, compared with 77.6% of patients in the control group (average follow-up of 452 days) (P=0.02). Graft survival was also significantly improved in groups 3 (88.5%) and 4 (92.5%), compared with the controls (72%) (P=0.007).Conclusions.The results suggest that dose and timing of DBMC infusions may be important variables affecting allograft survival. A randomized prospective trial is now in progress to compare group 3 DBMC infusion protocol with controls receiving OLTX alone.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Background.In an outbred pig model of total bowel transplantation, we previously showed that simultaneous donor-specific bone marrow infusion (DSBMI), rather than promoting engraftment, sensitizes recipients and causes rejection; it also aggravates the risk of generalized graft-versus-host disease (GVHD) and infection, and tends to reduce recipient and graft survival. Small and large animal models of bone marrow-induced transplant tolerance suggest that some form of recipient preconditioning (RPC) may facilitate engraftment of co-transplanted bone marrow cells and fully expose their tolerogenic potential.Methods.In a preclinical model, we prospectively studied the effect of RPC on simultaneous DSBMI and total (i.e., small and large) bowel transplantation. RPC consisted of whole body irradiation with 400 R (day 0); some recipients additionally received horse anti-pig antithymocyte globulin (days -2, -1, and 0). We studied six groups of outbred pigs, all of which underwent at least a total bowel transplant: group 1, nonimmunosuppressed control pigs (n=5); group 2, nonimmunosuppressed DSBMI pigs (n=13); group 3, tacrolimus pigs (n=7); group 4, DSBMI+tacrolimus pigs (n=15); group 5, RPC+nonimmunosuppressed DSBMI pigs (n=11); and group 6, RPC+DSBMI+tacrolimus pigs (n=14).Results.RPC did not prolong overall survival at 7, 14, 21, and 28 days after transplant. Survival rates were 100%, 100%, 86%, and 71% in group 3; 71%, 43%, 29%, and 29% in group 6; 55%, 9%, 0%, and 0% in group 5; and 60%, 0%, 0%, and 0% in Group 1. Moreover, RPC (groups 5 and 6) increased the incidence of death from rejection, GVHD, and infection when compared with group 3. Survival was significantly higher for RPC+DSBMI+tacrolimus pigs (group 6), compared with RPC+nonimmunosuppressed DSBMI pigs (group 5). Survival greater than 28 days was noted only in pigs that received tacrolimus after transplant: 71% in group 3 versus 29% in group 6. With both RPC and DSBMI (groups 5 and 6), rejection, GVHD, and infection were not mutually exclusive events. In groups 5 and 6, at autopsy, the incidence of rejection and GVHD was 17%; rejection and infection, 17%; and GVHD and infection, 45%. A combination of all three immunologic events was noted in 14%.Conclusions.RPC, combined with DSBMI, and with or without posttransplant immunosuppression, does not prolong survival after total bowel transplantation. Rather, it increases the incidence of death from rejection, GVHD, infection, or a combination of these three immunologic events. According to this preclinical study, RPC and unmodified DSBMI do not improve patient and graft outcome after total bowel transplantation and need to be refined before being applied clinically.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

A total of 847 inbred Lewis rats of mixed sex were used in this pancreaticoduodenal (Pd) donor aging study. Pd grafts were taken from 9- to 12-month-old donors and transplanted into 3-month-old recipients (thus, the first generation Pd graft, or 1 Pd). After 9 to 12 months, the same Pd grafts were again harvested and transplanted into 3-month-old rats (thus the 2 Pd generation). This cycle was repeated to obtain the 3, 4, and 5 Pd series. Sequential transplantation was able to extend the Pd grafts' mean survival time to 32 months for fourteen 4 Pd grafts, and to 39.2 months for four 5 Pd grafts (the longest lived graft survived for 42 months).The pancreas and duodenal sections of the grafts remained normal throughout the entire study. However, the aortic sections of the grafts (which were harvested to include the superior mesenteric and celiac arteries) all exhibited moderate to massive atherosclerotic changes by the 5 Pd mean survival age of 39.2 months. Such histological changes commenced even before 21 months of Pd graft age in some animals, gradually progressing to dilation of the aorta (and subsequent narrowing of aortic tributaries), as well as formation of an eggshell-like inner membrane shielding the aortic intima, by 42 months. Such atherosclerotic changes precluded transplantations beyond the 5 Pd series.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Long-term tolerance to class I-mismatched renal allografts can be induced in miniature swine by treatment with a short course of cyclosporine (CsA). Kidney recipients treated with CsA and untreated control kidney recipients both demonstrated infiltration of the transplanted kidney by mononuclear cells, which reached a maximum between postoperative days 8 and 11. Recipients that did not receive the tolerizing regimen rejected their grafts between postoperative days 8 and 12 in this model. The kinetics of cytokine gene expression, including interleukin (IL)-1α, IL-1β, IL-2, IL-6, IL-10, tumor necrosis factor, and interferon-γ (IFN-γ), within the grafted kidney of rejector and acceptor animals, were determined using Northern blot hybridization. A strong correlation between rejection and up-regulation of the IFN-γ gene was observed, whereas animals with long-term tolerance showed low levels of IFN-γ, but high levels of IL-10 gene transcription. None of the other cytokine genes demonstrated a reproducible pattern of expression that correlated with acceptance/rejection of allografts. Analysis of transcription patterns of cytokine genes in mononuclear cells purified from renal grafts confirmed the initial observations made on biopsies. The phenotype of graft-infiltrating cells (GIC) showed a dominance of CD8+cells, with an average of 66% single-positive cells and 19% CD4/CD8 double-positive cells, compared with 30% and 14%, respectively, for peripheral cells. Predominance of CD8+GIC was dictated neither by the MHC antigen disparity nor the rejector/acceptor status. These results, therefore, suggest that GIC represent a regulated combination of mononuclear cells producing local immune mediators that, in part, control the fate of allografts in this large animal model.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

The efficacy of murine monoclonal anti-interleukin 2 α chain receptor (Tac) antibodies is limited by a short half-life and the development of antibodies to the heterologous protein. The safety, pharmacokinetics-dynamics, and immunosuppressive effect of a humanized anti-Tac antibody (HAT) was evaluated in 12 renal transplant recipients. Ten patients received living related transplants (three HLA-identical matches and seven one-haplotype or zero-haplotype matches) and two patients received cadaver organs. The patients were divided into four HAT treatment arms: 0.5 mg/kg/week (n=4), 1 mg/kg/week (n=2), 0.5 mg/kg every other week (n=3), and 1 mg/kg every other week (n=3). The first dose of HAT was given within 12 hr before transplantation, and four additional doses were given after transplantation. Patients were also placed on cyclosporine, steroids, and azathioprine. Only one patient, a recipient of a cadaver kidney in the lowest HAT treatment arm, had a reversible rejection episode. The 10 recipients of living related transplants were compared with 17 historical controls treated with an identical immunosuppressive regimen except for HAT. Whereas none of the HAT-treated living related donor recipients had a rejection episode, 6 of 17 (41%) of the historical controls had a rejection episode in the first year after transplantation. There were no first-dose reactions after HAT therapy or other subsequent side effects. None of the patients experienced opportunistic infections or malignancies. One patient developed low-titer anti-HAT antibodies, although the patient maintained high serum HAT concentrations throughout the study. Immune monitoring showed that there were no changes in the percentage or absolute counts of CD3 cells or T-cell subsets after HAT therapy. However, there was a significant decrease in the number of circulating lymphocytes that expressed free Tac. The overall harmonic mean half-life of HAT was 273 hr. The results of this study indicate that HAT given at 1 mg/kg every other week for a total of five doses may provide therapeutic HAT concentration levels and result in good saturation of Tac receptors for at least 12 weeks after transplantation. In summary, HAT is safe and is well tolerated by patients. Its long half-life and lack of immunization could make it a very useful immunosuppressive drug.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Background.The search for more effective and less toxic immunosuppressive agents to control transplant rejection has led to the extensive testing of mycophenolate mofetil (MMF) in clinical renal transplantation.Methods.A pooled analysis of three phase III, randomized, double-blind, multicenter clinical trials conducted in the United States, Canada, Europe, and Australia was performed to further characterize the efficacy of MMF in renal allograft recipients. The three studies enrolled a total of 1493 patients. Tripleand quadruple-therapy regimens of cyclosporine, corticosteroids, and standardized MMF dosages with and without antilymphocyte induction were used: MMF in twice-daily doses of 1.0 g or 1.5 g (MMF 2 g or 3 g) was compared with placebo (PLA) or azathioprine (AZA). The primary efficacy endpoint in the individual trials was biopsy-proven rejection or treatment failure at 6 months. This pooled analysis focused on graft loss, patient death, incidence and treatment of rejection episodes, and graft function (serum creatinine) at 1 year.Results.At 1 year, the graft survival rate was 90.4% and 89.2% in the MMF 2 g and 3 g groups, respectively, compared with 87.6% in the PLA/AZA group. This difference was not statistically significant. MMF significantly reduced the incidence of rejection episodes: 40.8% for PLA/AZA patients versus 19.8% and 16.5% for the MMF 2 g and MMF 3 g groups, respectively. Renal function was consistently better for both MMF treatment groups at 3, 6, and 12 months.Conclusions.MMF proved superior to AZA as a posttransplant immunosuppressant in conjunction with cyclosporine and corticosteroids. MMF-treated groups showed reduced incidence and severity of rejection episodes, similar graft survival, and better graft function over 12 months.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

The enzyme-linked immunosorbent assay (ELISA) using HLA class I molecules purified from pooled platelets has the potential to detect HLA antibodies with increased efficiency without sacrificing sensitivity or specificity. This test, which was originally developed in our institution, has been independently validated by recent studies and is now commercially available. We now present evidence of its usefulness as a routine HLA antibody screening test for renal transplant patients. A total of 515 patients were tested monthly by ELISA (13.9 tests/patient) and by antiglobulin-enhanced panel reactivity (6.3 tests/patient). In patients found to be unsensitized, the incidence of false-positive results was less for ELISA than for the panel studies. In patients who were highly sensitized, both tests performed equally well, whereas discordant results were registered mainly in cases of mild sensitization. Because 66% of our patients were not sensitized, the ELISA was effective in reducing the number of more involved tests aimed at characterizing the antibodies. These results provide a foundation to use the pooled platelet HLA ELISA on a routine basis for HLA antibody screening.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

In order to understand in more detail the role of endogenous interleukin 1 receptor antagonist (IL-1ra) during bone marrow transplantation, IL-1ra serum levels of 28 patients undergoing allogeneic (n=25) or autologous (n=3) bone marrow transplantation were measured with a commercially available ELISA. In addition, the impact of intravenous immunoglobulin (IVIG) was evaluated by analyzing IL-1ra serum levels before and 2, 5, and 24 hr after IVIG infusion.IL-1ra measurements revealed a nadir of circulating IL-1ra levels 3-5 days after bone marrow transplantation, with an increase during conditioning and hematological reconstitution. Circulating IL-1ra levels were significantly increased in patients with cytomegalovirus (CMV) disease, CMV reactivation, graft-versushost disease (GVHD), or fever of unknown origin, when compared with time-matched controls without complications. Highest levels were observed in patients with CMV disease (1922±388 pg/ml), followed by patients with CMV reactivation (1575±435 pg/ml) and GVHD (1178±317 pg/ml). The magnitude of IL-1ra increase in GVHD was related to disease severity. Patients with grade III-IV GVHD developed higher IL-1ra levels than did patients with grade I-II GVHD. Lower but still significantly elevated IL-1ra levels were observed during fever of unknown origin (384±87 pg/ml). An increase of IL-1ra serum levels followed the administration of IVIG before transplantation and after hematopoietic reconstitution, but not during aplasia, pointing to the important role of hematopoietic cells in the production of IL-1ra.In conclusion, we show that IL-1ra release is related to conditioning regimen, hematopoietic reconstitution, complications of infectious and alloimmune etiology after bone marrow transplantation, and exogenously administered IVIG.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

The influence of mismatches for HLA-DR “split” specificities was investigated in more than 8000 cadaver kidney transplants. HLA-DR typing was performed using DNA methodology. Among first transplants, mismatches defined by HLA-DR split specificities did not have a deleterious influence. Among retransplants, however, graft survival was significantly decreased if a mismatch was defined, considering split specificities in patients with no mismatch according to the “broad” definition (P=0.04) and also in grafts with two split mismatches, which showed only one mismatch according to the broad definition (P=0.03). Moreover, consideration of further “subsplit” specificities resulted in clinically relevant mismatches only among retransplants. These data indicate that the recognition of HLA-DR split specificity mismatches is fundamentally different in primary and regraft recipients. The results imply that recipients and donors of kidney retransplants should be typed for HLA-DR split specificities and that these specificities should be considered for organ allocation.

ISSN:0041-1337    

出版商:OVID    

年代:1997

数据来源: OVID