Gary G. Singer

The fas antigen is involved in peripheral but not thymic deletion of T lymphocytes in T cell receptor transgenic mice

The role of a cell death-associated gene, fas, in T lymphocyte development and responses to antigen has been analyzed by breeding a transgenic T cell receptor specific for the 81-104 peptide of pigeon cytochrome c into fas-defective MRL-lpr/lpr and control MRL+/+ mice. Transgene-expressing T cells mature normally in both strains and populate peripheral lymphoid tissues in normal numbers. Mature CD4+ T cells from the lpr/lpr mice are resistant to suppression by high doses of antigen and to apoptotic cell death. In vivo administration of peptide antigen causes deletion of thymic T cells in both MRL-lpr/lpr and MRL+/+ strains. By contrast, antigen-induced deletion of peripheral T cells occurs in the MRL+/+ but not in the MRL-lpr/lpr strain. Therefore, the fas gene plays an essential role in activation-induced cell death in mature T lymphocytes, but not in the negative selection of immature cells in the thymus.

Prophylactic oral ganciclovir compared with deferred therapy for control of cytomegalovirus in renal transplant recipients.

BACKGROUND Treatment with prophylactic oral acyclovir, intravenous ganciclovir, or immunoglobulins to prevent cytomegalovirus (CMV) infection and disease in renal transplantation is associated with variable efficacy and significant expense. We studied control of CMV in renal transplant recipients using either prophylactic oral ganciclovir or deferred therapy with intensive monitoring with polymerase chain reaction (PCR) analysis. METHODS Forty-two recipients were followed for 6 months after transplantation. Ganciclovir (1000 mg p.o. t.i.d.; n=19) or acyclovir (200 mg p.o. b.i.d.; n=23) was begun at transplantation and continued for 12 weeks. PCR for CMV was performed on buffy-coat specimens every week for 15 weeks and at months 5 and 6. RESULTS No patients in the ganciclovir group, compared with 14 of 23 patients (61%) in the deferred-therapy group (P<0.0001), developed CMV disease during the first 12 weeks. In the ganciclovir group, 4 of 19 patients (21%) subsequently experienced 5 episodes, whereas 14 patients in the deferred-therapy group experienced 18 episodes (P=0.013 for subjects and P=0.026 for episodes). The time to disease was also delayed in the ganciclovir group compared with the deferred-therapy group (133+/-17 days vs. 51+/-7 days; P<0.0001). Oral ganciclovir also prevented CMV viremia during prophylaxis (2/19 patients [11%] vs. 23/23 patients [100%]). Time to CMV viremia was delayed in the ganciclovir group; however, 13/19 patients (68%) ultimately showed PCR evidence for CMV viremia (P=0.005). CONCLUSIONS An initial 12-week course of oral ganciclovir prevents CMV disease and infection in renal transplant recipients during prophylaxis, and the benefits persist after discontinuation.

Fulminant hepatic failure resulting from lamivudine-resistant hepatitis B virus in a renal transplant recipient: durable response after orthotopic liver transplantation on adefovir dipivoxil and hepatitis B immune globulin.

BACKGROUND Mutations in the hepatitis B virus (HBV) genome may occur during therapy. METHODS We report an asymptomatic HBV carrier who underwent transplantation for end-stage renal disease. She developed an HBV flare 6 months after transplantation and was placed on lamivudine. After initial rapid improvement, she relapsed clinically and virologically. She decompensated with jaundice, peripheral edema, ascites, encephalopathy, coagulopathy, and hepatorenal syndrome. A liver biopsy specimen revealed submassive necrosis. RESULTS Emergency liver transplantation was performed: lamivudine was discontinued. Hepatitis B immunoglobulin and adefovir dipivoxil were initiated. Sixteen months after orthotopic liver transplantation, she is HBV DNA seronegative with normal liver enzymes. Sequencing of HBV polymerase gene from preliver transplantation sera did not detect the usual lamivudine resistance mutations in the YMDD motif but instead two other mutations (F514-->L, L528-->M). Lamivudine resistance was demonstrated in vitro. CONCLUSIONS Asymptomatic HBV carriers may reactivate following renal transplantation after immunosuppression. Resistance to lamivudine may result in severe hepatic damage in immunocompromised patients.

Apoptosis, fas and systemic autoimmunity: the MRL-Ipr/Ipr model

Proteins encoded by the fas and fas ligand (fasL) genes are involved in apoptotic cell death in lymphocytes. In this article we review the recent elucidation of the role of the Fas-FasL interactions in the maintenance of tolerance to self antigens and in the homeostatic regulation of lymphocyte clonal expansion, and discuss the mechanisms of autoimmunity in Fas- and FasL-deficient mutant mouse strains.

Short course induction immunosuppression with thymoglobulin for renal transplant recipients

BACKGROUND The aim of this study was to demonstrate that 3-days of induction immunosuppression with thymoglobulin was as effective and safe as a 7-day course and reduced initial hospitalization after transplantation. METHODS This was a prospective, nonrandomized trial of 40 consecutive patients receiving thymoglobulin induction for 3 days and followed for 1 year. An historical group of 48 patients that received 7 days of thymoglobulin served as controls. RESULTS At 1 year, acute rejection (5 vs. 4%), graft survival (95 vs. 98%) and patient survival were similar; a composite end point of freedom from death, rejection, or graft loss, the event-free graft survival, was similar as was the safety profile. In the 3-day group, lymphocyte depletion was more sustained and initial hospitalization was significantly shorter (6 vs. 8 days). CONCLUSION Three-day induction with thymoglobulin is as effective and safe as seven days, decreases initial hospitalization and causes more sustained lymphocyte depletion.

Quantitative Polymerase Chain Reaction to Predict Occurrence of Symptomatic Cytomegalovirus Infection and Assess Response to Ganciclovir Therapy in Renal Transplant Recipients

Cytomegalovirus (CMV) DNA levels were measured by quantitative-competitive polymerase chain reaction (PCR) in weekly leukocyte samples from 50 renal transplant recipients, including 23 with symptomatic and 27 with asymptomatic CMV infection. Peak and week 4 CMV DNA levels were higher in symptomatic subjects (P = .07 and .02, respectively). In a logistic regression model, the logarithm of the week 4 level independently predicted symptomatic infection (odds ratio, 1.78 for a 1 log10 increase; 95% confidence interval, 1.14-2.78; P = .01). All subjects whose week 4 level exceeded 1000 copies/100,000 leukocytes developed symptoms. In subjects with adequate samples for analysis, CMV levels declined exponentially with ganciclovir treatment, with an average half-life of 3.3 days. Levels exceeding 10,000 copies were associated with prolonged time to clearing of CMV DNA. Potential clinical applications of quantitative CMV PCR include predicting occurrence of symptomatic first episodes after transplantation and individualizing duration of antiviral therapy.

The effects of lipid-lowering agents on acute renal allograft rejection

Background. Preliminary results from clinical trials suggest that 3-hydroxy-3-methylglutaryl co-enzyme A reductase inhibitors may help prevent acute renal allograft rejection. However, the mechanism for this putative effect of 3-hydroxy-3-methylglutaryl co-enzyme A reductase inhibitors, and whether it is independent of lipid-lowering per SE are unknown. Methods. Immediately after renal transplantation we randomly allocated (proportioned 2:1:2) patients to: 1) simvastatin (10 mg/day, n=53), 2) simvastatin placebo plus gemfibrozil (dose adjusted for renal function, n=36), and 3) simvastatin placebo (n=52). Results. Simvastatin, but not gemfibrozil, reduced total and low density lipoprotein cholesterol during the first 90 days posttransplant. There were no major adverse effects of therapy. However, there were no effects of treatment on acute rejection. Indeed, survival free of acute rejection at 90 days was 72% in the simvastatin group, 72% in the gemfibrozil group, and 77% in the placebo control group (P =0.771). A post hoc power analysis suggested that there was only a 7.5% chance that a true effect of simvastatin on acute rejection (versus placebo) was not detected, and a 2.5% chance that an effect of gemfibrozil on acute rejection (versus placebo) was not detected in this study. Conclusion. Lipid-lowering agents may not reduce the incidence of acute renal allograft rejection. However, additional studies are needed to confirm this observation. In the mean time, many if not most renal transplant recipients should be treated with HMG-CoA reductase inhibitors starting early posttransplant to prevent cardiovascular disease complications. The results of this study suggest that starting lipid-lowering therapy immediately after renal transplantation is both safe and effective in lowering total and low density lipoprotein cholesterol.

Peripheral blood microchimerism in human liver and renal transplant recipients : Rejection despite donor-specific chimerism

BACKGROUND Development of donor-specific microchimerism (DSM) has been proposed as one of the possible mechanisms for induction and maintenance of allograft tolerance. The aim of this study was to determine: (1) the state of DSM in liver transplant (LTx) and renal transplant (RTx) recipients, (2) whether the persistent presence of an allograft is a requirement for maintenance of chimerism, and (3) whether donor-specific blood transfusions (DST) facilitate chimerism development in RTx recipients and whether this correlates with allograft function. METHODS Qualitative and quantitative analysis of DSM in peripheral blood of LTx and RTx recipients was assessed by polymerase chain reaction and competitive polymerase chain reaction using HLA-DR probes for mismatched antigens between the donor and recipient. RESULTS LTx recipients (11 of 12) who had or were having rejection were positive for DSM in circulation compared with 4 of 11 with normal allograft function (P<0.01). The number of donor cells did not correlate with allograft function. LTx recipients (4 of 4) who lost their first allograft and underwent retransplantation retained DSM for the first donors. RTx recipients who received DST (8 of 8) were positive for DSM compared with 6 of 12 of nontransfused recipients (P<0.045). CONCLUSIONS The results suggest that LTx and RTx recipients undergo rejection despite DSM. The development of DSM may not be a prerequisite for normal allograft function. Once DSM is established, the presence of the allograft is not required for maintenance of chimerism. DST facilitated the development of DSM in RTx recipients. Direct correlation was not observed between the development of DSM and allograft function in either DST or nontransfused RTx recipients.

Economic cost of expanded criteria donors in cadaveric renal transplantation: Analysis of medicare payments.

Background. The use of expanded criteria donors (ECDs) in cadaveric renal transplantation is increasing in the US.We assess the economic impact of the use of ECDs to the Medicare end stage renal disease program. Methods. The United Nations for Organ Sharing renal transplant registry was merged to Medicare claims data for 42,868 cadaveric renal transplants performed between 1991–1996 using USRDS identifiers. Only recipients for whom Medicare was the primary payer were considered, leaving 34,534 transplants. An ECD was defined as (1) age ≤5 or ≥55 years, (2) nonheart-beating donors, donor history of (3) hypertension or (4) diabetes. High-risk recipients (HRR) were age >60 years, or a retransplant. Medicare payments from the pretransplant dialysis period were projected forward to provide a financial “breakeven point” with transplantation. Results. There were 25,600 non-HRR transplants, with 5,718 (22%) using ECDs, and 8,934 HRR transplants, of which 2,200 (25%) used ECDs. The 5-year present value of payments for non-ECD/non-HRR donor/recipient pairings was

Cadaveric versus living donor kidney transplantation: A medicare payment analysis.

121,698 vs.