Case Report Demonstrating the Safe and Effective Means of Expanding the Donor Pool With Livers Recovered From Brain-Dead Donors After Ethylene Glycol Toxicity.

The growing disparity between organ supply and demand has become the greatest hurdle facing transplant professionals and life-saving transplants. Because the organ shortage has become the rate-limiting step to effective transplants, it is critical for the transplant community to identify viable mechanisms to expand the donor pool and use every available allograft. Although using kidneys from deceased donors whose demise was secondary to ethylene glycol (EG) toxicity requires great deliberation and precise timing as described by Barbas et al [5], using hepatic allografts in this setting involves far less risk. The following is a discussion of a 61-year-old male who was diagnosed with end-stage liver disease secondary to non-alcoholic steatohepatitis and ultimately underwent a life-saving transplant with a liver recovered from a donor with EG-induced brain death and allocated nationally due to trepidation by local and regional centers to use the liver from a donor after EG toxicity.

Analysis of cell viability using time-dependent increase in fluorescence intensity.

We report the use of resazurin (AlamarBlue) dye in a robust assay for cell viability of primary cells. Human mononuclear cells were used here for immunological studies, but the method can be applied to monitor reduction potential of any living cell. Reduction of AlamarBlue dye is widely used in several commercial assays of cell viability. Although it is fast and easy with immortal cell lines, the method is impractical for the primary cells due to their slower metabolic activity. We propose that the viability of human primary cells can be determined with AlamarBlue by monitoring the increase in fluorescence intensity in a matter of a few hours. In the presence of AlamarBlue, the dynamic increase in cellular reduction capacity is linear for several hours or, alternatively, the assay can be repeated to monitor the viability at any time point of cell culture. In addition to testing cellular growth rates and cytotoxicity, the application can be used to compare sample quality of cells that have been frozen or represent a pool of multiple donors. This application of the AlamarBlue cell viability assay is simple, rapid, and cost-effective, and therefore it is also well suited for high-throughput studies.

Differential regulation of PTEN expression by androgen receptor in prostate and breast cancers.

Prostate cancer and breast cancer are the most common malignancies in the western world. Androgen receptor (AR) and PTEN both have been well documented to have important roles in prostate carcinogenesis. In contrast, AR and PTEN in breast carcinogenesis have not been well studied. Furthermore, the crosstalk and connection between those two pathways remain unclear. Increased AR expression in prostate cancers, combined with decreased PTEN expression, portends a poor clinical outcome. Paradoxically, both high AR and high PTEN levels, detected by immunohistochemistry, in primary breast carcinomas have been associated with better disease-free survival. Here, we performed in silico analysis of publicly available microarray data sets from prostate or breast carcinomas. We found an inverse correlation between AR and PTEN transcript expression in prostate cancer tissues in contrast to the positive correlation in breast cancer. These data led us to hypothesize that AR may directly affect PTEN transcriptional regulation in prostate and breast cancer cells. Here, we show for the first time that AR inhibits PTEN transcription in prostate cancer cells, whereas AR upregulates PTEN transcription in breast cancer cells, which mechanistically explains both the immunohistochemical PTEN-AR expressional data noted in clinical trials and in our in silico analysis of the transcriptomes of breast and prostate cancers. In addition, we have fine-mapped the AR-binding motif within the PTEN promoter. Here we show that, in patients with Cowden syndrome, an inherited cancer syndrome caused by germline mutations scattered throughout PTEN, point variants affecting the 3' end of the AR-binding motif result in abrogation of androgen-mediated transcriptional regulation of PTEN expression. We may speculate that the differential AR effect on PTEN may begin to explain organ-specific and perhaps sex-specific neoplasia predisposition in Cowden syndrome, as well as why only a fraction of women with germline PTEN mutations develop breast cancer, depending on the androgen steroid milieu and levels.

Genetic and phenotypic heterogeneity in the PTEN hamartoma tumour syndrome.

Germline PTEN (Phosphatase and TENsin homologue deleted on chromosome TEN) mutations predispose to phenotypically diverse disorders that share several overlapping clinical features: Cowden syndrome, Bannayan-Riley-Ruvalcaba syndrome, Proteus syndrome and Proteus-like syndrome, collectively classified as PTEN hamartoma tumour syndrome (PHTS). The meticulous acquisition and documentation of PHTS phenotypic data at different levels and the profiling of the plethora of genetic changes in PTEN and other genes within the same or related pathways are important in resolving the challenge of discriminating heritable cancers from sporadic PHTS-mimicking clinical features. The characterization of PTEN and PTEN-related pathways from a multidisciplinary perspective underscores the importance of incorporating data from different -omics, which is crucial for the advancement of personalized medicine.

The activation state of human intrahepatic lymphocytes.

The immune tolerance induced by the liver as an allograft is difficult to reconcile with the evidence that the liver selectively accumulates activated T cells from the circulation. However, much of this information is based on murine liver lymphocytes that were isolated using enzymatic digestion. In the present study we made use of a novel resource, the lymphocytes isolated during the perfusion of living donor liver lobe prior to transplantation. These healthy human liver lymphocytes displayed surface markers indicating a high degree of activation of natural killer cells, CD56(+) T cells, CD4(+) T cells and CD8(+) T cells. These properties were independent of enzymatic treatment or the details of cell isolation. We conclude that the healthy human liver is a site of intense immunological activity.

Arterioportal fistulae following segmental liver transplantation in a child.

We report a case of arterio-portal fistulae in a 12-month-old-child following a segmental liver transplantation. The fistula, probably the result of mass ligature of a vascular pedicle during back table allograft reduction, is to our knowledge the first such case reported. Diagnosed on the third post-operative day, the fistula was successfully managed with transcatheter coil embolization. The child is well and asymptomatic, 33 months after transplantation. In addition to those seen in whole organ transplantation, there are a few complications specifically related to segmental transplantation. These complications, although infrequent, are a direct consequence of the back table liver partition, as in the case herein reported.

A 27-year experience with surgical treatment of Budd-Chiari syndrome.

OBJECTIVE: To determine the effects of surgical portal decompression in Budd-Chiari syndrome (BCS) on survival, quality of life, shunt patency, liver function, portal hemodynamics, and hepatic morphology during periods ranging from 3.5 to 27 years. SUMMARY BACKGROUND DATA: Experiments in the authors' laboratory showed that surgical portal decompression reversed the deleterious effects of BCS on the liver. This study was aimed at determining whether similar benefit could be obtained in patients with BCS. METHODS: From 1972 to 1999, the authors conducted prospective studies of the treatment of 60 patients with BCS who were divided into three groups: the first had occlusion confined to the hepatic veins treated by direct side-to-side portacaval shunt (SSPCS); the second had occlusion involving the inferior vena cava (IVC) treated by a portal decompressive procedure that bypassed the obstructed IVC; and the third group, who had advanced cirrhosis and hepatic decompensation and were referred too late for treatment by portal decompression, required orthotopic liver transplantation. RESULTS: In the 32 patients with BCS resulting from hepatic vein occlusion alone, SSPCS had a surgical death rate of 3%, and 94% of the patients were alive 3.5 to 27 years after surgery. All 31 survivors remained free of ascites and almost all had normal liver function. No patient with a patent shunt had encephalopathy. The SSPCS remained patent in all but one patient. Liver biopsies showed no evidence of congestion or necrosis, and 48% of the biopsies were diagnosed as normal. Mesoatrial shunt was performed in eight patients with BCS caused by IVC thrombosis. All patients survived surgery, but five subsequently developed thrombosis of the synthetic graft and died. Because of the poor results, mesoatrial shunt was abandoned. Instead, a high-flow combination shunt was introduced, consisting of SSPCS combined with a cavoatrial shunt (CAS) through a Gore-Tex graft. There were no surgical or long-term deaths among 10 patients who underwent combined SSPCS and CAS, and the shunts functioned effectively during 4 to 16 years of follow-up. Ten patients with advanced cirrhosis were referred too late to benefit from surgical portal decompression, and they were approved and listed for orthotopic liver transplantation. Three patients died of liver failure while awaiting a transplant, and four patients died after the transplant. The 1- and 5-year survival rates were 40% and 30%, respectively. CONCLUSIONS: SSPCS in BCS with hepatic vein occlusion alone results in reversal of liver damage, correction of hemodynamic disturbances, prolonged survival, and good quality of life when performed early in the course of BCS. Similarly good results are obtained with combined SSPCS and CAS in patients with BCS resulting from IVC occlusion. In contrast, mesoatrial shunt has been discontinued in the authors' program because of an unacceptable incidence of graft thrombosis and death. In patients with advanced cirrhosis from long-standing, untreated BCS, orthotopic liver transplantation is the only hope of relief and results in the salvage of some patients. The key to long survival in BCS is prompt diagnosis and treatment by portal decompression.

Tolerance induced by bone marrow chimerism prevents transplant vascular sclerosis in a rat model of small bowel transplant chronic rejection.

BACKGROUND: The major impediment to success in solid organ transplantation is chronic rejection (CR). The characteristic lesion of CR is transplant vascular sclerosis (TVS). Although the mechanism of TVS is thought to have an immunologic basis, in humans immunosuppression does not prevent or reverse it. One possible therapy to prevent TVS is induction of donor-specific tolerance. Bone marrow chimerism has been successful in inducing tolerance in acute and chronic rejection heart and kidney transplant models. The highly immunogenic small bowel (SB) allograft provides a rigorous test of the efficacy of this tolerance regimen. We examined whether induction of tolerance by bone marrow chimerism could prevent TVS in a model of Fisher 344 (F344) to Lewis (LEW) rat SB transplantation. METHODS: Bone marrow chimeras (BMC) were created by transplantation of T-cell-depleted F344 bone marrow into irradiated LEW rats. Chimerism was assessed by flow cytometric method. F344 SB, heterotopically transplanted into the chimeras, was clinically and histologically assessed for CR. F344 SB grafts, transplanted into cyclosporine-A-treated LEW recipients, served as control grafts for CR. RESULTS: Cyclosporine-A-treated LEW rats chronically rejected F344 SB grafts. By contrast, the BMC group demonstrated tolerance and had long-term SB graft survival (>120 days) without TVS. The BMC demonstrated immunocompetence by prompt rejection of third party ACI (RT1av1) SB allografts. CONCLUSIONS: Bone marrow chimerism prevents chronic graft failure secondary to TVS in a model of chronic SB rejection. TVS fails to develop when tolerance is established, suggesting that the mechanisms involved in TVS are, in part, immunologically mediated.

Lifelong prevention of mesangial enlargement by whole pancreas transplantation in rats with diabetes mellitus.

BACKGROUND: Mesangial enlargement (ME) is one of the hallmark lesions of diabetic nephropathy and plays a major role in diabetic renal failure. Conventional treatment of type 1 diabetes mellitus with insulin injections, diet, and medications has often failed to prevent development and progression of ME, presumably because of difficulty in achieving tight metabolic control. Although many pancreas transplantations have been done in patients with type 1 diabetes mellitus, there is insufficient information about their influence on ME or other diabetic lesions that are responsible for its morbidity and mortality. HYPOTHESIS: Whole pancreas transplantation will prevent diabetic ME throughout the life of the rat with alloxan-induced diabetes mellitus. DESIGN: Mesangial enlargement was studied for 28 months by a highly reproducible quantitative morphologic method in 55 nondiabetic control rats, 57 control rats with alloxan-induced diabetes mellitus, 97 diabetic rats that received a pancreaticoduodenal isograft shortly after the induction of diabetes mellitus, and 126 diabetic rats that received a duct-ligated pancreas isograft shortly after the induction of diabetes mellitus. Mesangial enlargement was determined by measuring the area occupied by camera lucida tracings of the mesangium using an electronic planimeter connected to a computer. RESULTS: Monthly metabolic studies showed that whole pancreas transplantation maintained very tight metabolic control of diabetes mellitus. Alloxan-induced diabetes mellitus produced progressive accumulation of mesangial matrix and progressive enlargement of all elements of the mesangium during the study. The 2 types of whole pancreas transplants provided lifelong protection against abnormal ME (P = .006). CONCLUSIONS: These results, combined with our previous finding of lifelong prevention of abnormal glomerular capillary basement membrane thickening, demonstrate that whole pancreas transplantation performed early in the course of alloxan-induced diabetes mellitus is capable of preventing diabetic kidney lesions. Moreover, these results suggest that whole pancreas transplants might be useful preventive therapy in patients with diabetes mellitus who undergo kidney transplantation for renal failure, in whom recurrence of nephropathy often develops in the transplanted kidney.

Sonography: a useful tool to detect the mechanical causes of renal transplant dysfunction.

PURPOSE: The purpose of this study was to evaluate the utility of sonography in distinguishing between mechanical and nonmechanical causes for renal transplant dysfunction. METHODS: We reviewed all ultrasound examination reports (n = 286) for 63 consecutive patients who received 64 renal transplants. We assessed the sensitivity and specificity of different degrees of hydronephrosis (mild, moderate, or severe) in detecting urinary tract obstruction; different volumes of new or increasing peritransplant fluid in detecting urine leaks; different total volumes of peritransplant fluid in predicting significant compression of the transplant; and Doppler vascular criteria for predicting arterial and venous occlusion. RESULTS: All mechanical complications were detected (100% sensitivity) with specificities of 91.9% for ureteral obstruction (criterion, moderate hydronephrosis), 83.4% for urine leaks (criterion, any new fluid or any increase), 91.4% for fluid collections that compressed the transplant (criterion, > 100 ml), and 100% for vascular occlusion (criteria, no flow for arterial occlusion; no venous flow and reversal of arterial flow during diastole for venous occlusion). CONCLUSIONS: Sonography is very useful in distinguishing between mechanical and nonmechanical causes for renal transplant dysfunction. It has high sensitivity and acceptable specificity in this setting.

Tolerance induction permits the development of graft-versus-host disease: donor-mediated attack following small bowel transplantation in mixed chimeras.

The induction of tolerance to organ allografts would eliminate acute and chronic rejection as well as the need for nonspecific immunosuppression. We have shown that tolerance induced through the creation of mixed allogeneic bone marrow chimeras allows for the long-term engraftment of cardiac and small bowel allografts across strong multiple major histocompatibility barriers. The possibility that tolerance might render the host susceptible to graft-versus-host disease (GVHD) has not been investigated in this or other models of tolerance. To test this possibility chimeras were created by transplantation of T-cell depleted ACI and Lewis bone marrow into lethally irradiated Lewis rats. Chimerism was determined post bone marrow transplant (BMTx) by flow cytometry of lymphocytes from reconstituted animals. ACI/Lew chimeras (ALC), Lewis/ACI F1 (LACF1), and Lewis (LEW) rats all received heterotopic ACI vascularized small bowel grafts. A second group of chimeras received small bowel grafts from ACI rats pretreated with low dose irradiation to eliminate T-cells from the graft. LEW-->LEW small bowel isografts were also performed. Animals were examined for evidence of GVHD by clinical signs and histologic examination of biopsied tissues. GVHD was quantified using the popliteal lymph node enlargement assay. All LACF1 rats developed severe lethal GVHD following ACI small bowel transplant. Bone marrow chimeras, ALC (n = 6), developed fatal GVHD in a similar fashion after receiving a small bowel transplant. LEW-->LEW isografts and chimeras receiving bowel from irradiated ACI rats survived long term without GVHD while ACI-->LEW allogeneic transplants all underwent acute rejection. GVHD or its absence was confirmed histologically. Popliteal lymph node enlargement indices reflected the presence of GVHD in the chimeras (1.87) and LACF1 (5.4) receiving allografts, but not in isografts or chimeras receiving irradiated allogeneic transplants. Analysis of cytokines in the tongues of rats undergoing GVHD showed elaboration of Th1 type proinflammatory cytokines which was not seen in isografted rats or rats receiving preirradiated small bowel. These results demonstrate that tolerance induction through mixed chimerism results in susceptibility to small bowel induced GVHD. Preirradiating the donor bowel prior to SBTx can prevent GVHD.

Urine leaks in renal transplant patients. Diagnostic usefulness of sonography and renography.

We evaluated the utility of sonography and nuclear medicine renography in the detection of urine leaks in 57 renal transplant patients. Sonography and renography were equally sensitive in detecting leaks. But renography was more specific and therefore accurate (p < 0.0001) in detecting leaks. Urine leaks should be considered on sonography, which is often the first imaging study ordered in evaluating renal transplants, with new or increasing peritransplant fluid collections. Leaks should be confirmed by renography before performing additional invasive radiologic or surgical procedures.

A more versatile and reliable method for renal transplantation in the rat.

This study describes the authors' experience with a new method of orthotopic renal transplantation in the rat. This technique combines previously described modifications with the use of the donor inferior vena cava as a conduit to perform an end-to-side venous anastomosis. Survival was 87% and 80% at 3 and 120 days, respectively. Patency was 80% at 120 days, and histologic examination revealed normal renal architecture and parenchyma, with no evidence of ischemic injury. This technique offers a refinement of previous techniques and is reliable, flexible, and can be easily learned by novice microvascular surgeons.

Tolerance induction by intrathymic inoculation prevents chronic renal allograft rejection.

BACKGROUND: These experiments investigated the ability of the donor-specific unresponsiveness created by the intrathymic inoculation of donor alloantigen to effectively prevent chronic rejection in an established rat model of chronic renal allograft rejection. METHODS: Three study groups were examined: (1) Allograft controls--F-344 rats received a Lewis renal allograft plus 10 days of low-dose cyclosporine (CsA); (2) isograft controls--F-344 rats received an F-344 renal isograft and low-dose CsA; (3) experimental group--F-344 rats received a T-cell depleted syngeneic bone marrow transplant and intrathymic injection of Lewis bone marrow. Twenty-one days after bone marrow transplant, these animals received a Lewis renal allograft. RESULTS: Allograft controls demonstrated severe parenchymal fibrosis; isograft controls and intrathymic (IT) animals failed to develop this lesion. Immunohistochemical analysis revealed increased CD4+ T cells infiltrating the cortex of the allograft controls. Cytokine interferon-gamma and interleukin-2 transcripts were strongly positive in allograft controls and were absent from isograft controls and IT allografts as determined by reverse transcriptase-polymerase chain reaction. Analysis of tolerant grafts by flow microfluorimetry and genomic DNA amplification could not detect chimerism to a level of < 0.1%. CONCLUSION: IT inoculation of donor alloantigen can confer long-term unresponsiveness and prevent the development of the characteristic lesions of chronic rejection.

Use of intraoperative ultrasonography during hepatic transplantation.

The aim of this study was to evaluate if intraoperative vascular ultrasonography is of clinical value in the perioperative management of hepatic transplant patients. Fifteen intraoperative ultrasonographic examinations were performed on 13 patients (five female, eight male) during transplantation. These patients had clinically suspected vascular compromise. Among the 13 patients studied intraoperatively, five were correctly diagnosed as having hemodynamically significant vascular compromise. Of the intraoperative vascular sonographic examinations, the results of 13 were in concordance with the surgical impression as to whether further intervention was necessary or if the procedure could be terminated. Intraoperative sonography demonstrates potential to be of aid to the surgeon in recognition of vascular compromise.

Experimental, clinical, and metabolic results of side-to-side portacaval shunt for intractable cirrhotic ascites.

BACKGROUND: Intractable ascites, refractory to medical therapy, occurs in approximately 10 percent of patients with ascites from cirrhosis and is almost always fatal. Sinusoidal hypertension resulting from hepatic venous outflow obstruction plays a primary role in the pathogenesis of cirrhotic ascites and provides the rationale for decompression of the liver by side-to-side portacaval shunt in treatment of intractable ascites. This report presents the experimental basis for the use of side-to-side shunt and long-term results of a prospective study in 34 selected patients with intractable cirrhotic ascites. STUDY DESIGN: In the experimental studies, hepatic venous outflow obstruction and massive ascites were produced in dogs by ligation of the hepatic veins, and the effect of portacaval shunts on ascites, thoracic duct lymph flow, and aldosterone secretion were measured. In the clinical study, 34 carefully selected patients with cirrhosis (91 percent alcoholic) and truly intractable ascites (failure of medical therapy for 5 to 24 months) underwent side-to-side portacaval shunt. The effects on ascites, survival, metabolic abnormalities, and quality of life were studied prospectively during follow-up that was longer than 5 years in all but two patients. Quantitative Child's risk classes in percent of patients were A in 0, B in 68, and C in 32. RESULTS: In the experimental studies, side-to-side portacaval shunt permanently relieved severe ascites, reduced the 13-fold increase in thoracic duct lymph flow rate to almost normal, and abolished the aldosterone hypersecretory response to minimal hepatic venous outflow obstruction. End-to-side portacaval shunt was much less effective. In the clinical study, side-to-side portacaval shunt reduced mean portal vein-inferior vena cava pressure gradient from 282 mm saline to 4 mm and permanently relieved all patients of ascites without subsequent requirement of diuretic therapy. Two patients who died of hepatoma, and one who died of heart failure developed terminal ascites. Thirty-day mortality rate was 6 percent, and long-term survival rates at 5, 10, and 15 years were 75 percent, 74 percent, and 73 percent. In metabolic studies, side-to-side shunt produced marked diuresis and natriuresis and abolished hypersecretion of aldosterone. Quality of life was generally improved as a result of a low incidence of recurrent portal-systemic encephalopathy (6 percent), abstinence from alcohol in 91 percent, improvement in liver function in 81 percent, and improvement in Child's risk class. The portacaval anastomosis remained permanently patent in every patient. CONCLUSIONS: Side-to-side portacaval shunt is very effective treatment of intractable ascites from cirrhosis. Our results are attributable to careful selection of patients, an organized system of care, and a program of rigorous, lifelong follow-up that emphasizes abstinence from alcohol and dietary protein restriction.

Portal vein thrombosis in cirrhosis with variceal hemorrhage.

Organized thrombus in the main trunk of the portal vein was encountered in 85 (6.5%) of 1300 patients with cirrhosis and variceal hemorrhage who underwent direct portacaval shunt (PCS). The thrombus was successfully removed with restoration of portal blood flow in all patients by phlebothrombectomy and balloon catheter extraction. Of the 85 patients, 65 were among 400 unselected patients who underwent emergency PCS (16%), and 20 were among 900 selected patients who underwent elective PCS (2%). All patients were closely followed for at least 5 years. Patients with portal vein thrombosis (PVT) had more advanced liver disease than those without PVT, reflected preoperatively in significantly higher (P < 0.01) incidences of ascites (75%), severe muscle wasting (52%), varices of very large size (94%), the hyperdynamic state (94%), severe hypersplenism with a platelet count of less than 50,000/mm3 (92%), and placement in Child's class C (52%). Side-to-side PCS reduced the portal vein-inferior vena cava pressure gradient to a mean of 23 mm saline solution in patients with PVT, similar to the marked pressure reduction obtained in patients without PVT. PCS promptly stopped variceal bleeding in all patients in the emergency PCS group. Permanent prevention of recurrent variceal bleeding was successful in 95% of patients with PVT and more than 99% of patients without PVT. Survival rates were similar in patients with and without PVT. In patients with PVT, survival rates at 30 days and 1, 5, 10, and 15 years following emergency PCS were 69%, 66%, 65%, 55%, and 51%, respectively, and following elective PCS were 95%, 90%, 70%, 65%, and 60%, respectively. Quality of life was similar in patients with and without PVT. Long-term PCS patency was demonstrated yearly in 93% of patients in the group with PVT and in 99.7% of patients without PVT. Other similarities after 5 years between patients with and without PVT, respectively, were the incidences of recurrent encephalopathy (9% vs. 8%), alcohol abstinence (61% vs. 64%), improved liver function (68% vs. 62% to 75%), and return to work (52% vs. 56% to 64%). It was concluded that in patients with cirrhosis and variceal hemorrhage it is almost always possible to remove portal vein thrombus by means of phlebothrombectomy and then perform a direct PCS with results similar to those achieved in the absence of PVT.

Induction of specific tolerance through mixed hematopoietic chimerism prevents chronic renal allograft rejection in a rat model.

BACKGROUND: Chronic rejection is the leading cause of late graft loss in kidney transplantation. We tested the ability of mixed hematopoietic chimerism to prevent chronic renal allograft rejection in an established rat model and described possible mechanisms responsible for this tolerance. METHODS: Mixed hematopoietic chimerism was established in lethally irradiated F-344 rats by reconstitution with Lewis bone marrow. Four groups (n = 5 each) received orthotopic kidney transplants: (1) allograft controls, (2) isograft controls, (3) experimental chimeras, and (4) specificity control. After 120 days kidney grafts were examined histologically, immunohistochemically, and for cytokine interferon-gamma, interleukin-2 (IL-2), IL-4, and IL-10 gene transcripts by means of reverse transcriptase polymerase chain reaction techniques. RESULTS: Allograft control group exhibited severe parenchymal fibrosis; isograft control and chimera groups failed to develop this lesion. Immunohistochemical analysis revealed increased CD8+ lymphocytes and ED-1+ monocyte-macrophages infiltrating the tubulointerstitium of control allografts. Interferon-gamma and IL-2 were absent in isografts. IL-4 was absent and IL-10 was positive in all grafts. Chimeras promptly rejected third-party allografts. CONCLUSIONS: Induction of specific tolerance through mixed hematopoietic chimerism prevents chronic renal allograft rejection. These results support the hypothesis of an immunologic basis of chronic rejection and advance previous observations that the induction of specific tolerance enables long-term solid organ transplantation without the use of immunosuppression.