Prognostic value of malignant cells in pleural lavage at thoracotomy for bronchial carcinoma

BACKGROUND: It has been reported previously that liver grafts and liver cells seem to be tolerogenic, based on the high frequency of spontaneous tolerance after orthotopic liver transplantation in rodents and on the phenomenon of portal venous tolerance in other models. The purpose of the current study was to characterize in vivo immune responses to allogeneic hepatocytes transplanted into the portal circulation. METHODS: In this functional model of hepatocyte transplantation, "donor" hepatocytes from mice transgenic for human alpha1-antitrypsin (hA1AT) were transplanted by intrasplenic injection into host mice and the secreted hA1AT protein measured in host serum to determine hepatocellular graft survival. Host immune responses were assessed by measurement of donor-specific alloantibodies and delayed-type hypersensitivity responses. In some experiments, liver nonparenchymal cells (NPCs) were co-transplanted with the allogeneic hepatocyte transplant. RESULTS: Allogeneic hepatocyte transplant into immunocompetent hosts resulted in loss of host serum hA1AT by days 7-10 after transplant, whereas syngeneic hosts maintained long-term hepatocellular graft survival as reflected by persistence of serum hA1AT for > 20 weeks. Allogeneic hepatocyte transplantation resulted in the development of donor-specific alloantibody and delayed-type hypersensitivity responses, as well as a "second set" response of accelerated hepatocellular graft rejection after a second transplant. Pretransplantation or co-transplantation of donor-matched liver NPCs at the time of allogeneic hepatocyte transplantation did not prolong hepatocellular allograft survival. CONCLUSIONS: Allogeneic hepatocytes introduced into the portal circulation via intrasplenic injection are immunogenic not tolerogenic and stimulate a weak humoral and strong cell mediated host immune response in vivo. Co-transplantation or pretransplantation of allogeneic liver NPCs did not protect allogeneic hepatocytes from immunologic rejection.     

Analysis of the relationship between chimerism and the allgeneic humoral response

BACKGROUND: Persistence of antigens has been suggested to play a role in two opposing immunological phenomena: tolerance and memory. Therefore, we studied the impact of chimerism on alloreactive antibody (allo-Ab) production in kidney transplant patients. METHODS: Thirty-five female renal transplant recipients of male donor organs were classified into the following groups: group 1, 13 sensitized uremic patients on dialysis; group 2, 5 nonsensitized uremic patients on dialysis; group 3, six sensitized patients experiencing graft rejection (3 acute vascular, 1 acute cellular, and 2 chronic); and group 4, 11 nonsensitized with functioning allografts (9 with good function, 1 with acute cellular rejection, and 1 with chronic rejection). Mean duration of dialysis after graft failure was similar in groups 1 (56+/-29.7 months) and 2 (41.8+/-42.4 months), as was dialysis efficiency. Chimerism was measured indirectly in the peripheral blood lymphocytes by polymerase chain reaction amplification of a specific Y chromosome DNA gene sequence with a detection sensitivity limit of 1 male cell per 1 million female cells. Allo-Ab production was measured by the PRA-STAT enzyme-linked immunosorbent assay (Sangstat) method. RESULTS: Chimerism was observed in 60% of groups 1 and 2, 83% of group 3, and 82% of group 4. Among all groups, graft existence, irrespective of its function, positively predicted chimerism in 92% with a sensitivity of 88% and a specificity of 78%. In group 3, all three patients with acute vascular rejection had chimerism and donor-specific allo-Abs. In group 4, eight of the nine patients with no rejection had chimerism. CONCLUSION: Chimerism relates to persistence of allogeneic stimulus irrespective of its function. Chimerism did not confer protection against allo-Ab production or vascular rejection, and its existence was not crucial for sustenance of allo-Ab production.     

Mycophenolic acid: a welcome adjunct immunosuppressant after organ transplants

Three major double-blind trials in kidney transplantation patients have shown that mycophenolic acid (mycophenolate mofetil), added to an immunosuppressive regimen consisting of cyclosporine and prednisone, reduces the incidence of acute rejection after kidney transplantation by 50%, during the first six months. This statistically significant reduction is achieved equally with daily doses of 2 or of 3 g. In view of the fact that the side effects (diarrhoea, abdominal cramps, leukopenia) are more frequently found in the patients treated with 3 g, it is advised to prescribe 2 g mycophenolic acid. As acute rejection is a risk factor for the development of chronic rejection and because a beneficial effect of mycophenolic acid on chronic rejection in animal models has been observed, there may also be an effect on late graft loss due to chronic rejection after kidney transplantation in man.     

Mycophenolate mofetil decreases rejection in simultaneous pancreas-kidney transplantation when combined with tacrolimus or cyclosporine

BACKGROUND: Historically, the acute rejection rates in simultaneous pancreas-kidney (SPK) recipients have been extremely high (50-80%), with many second and third rejection episodes despite the use of quadruple immunosuppression (antibody induction and cyclosporine [CsA]-azathioprine [AZA]-based maintenance immunosuppression). Although this acute rejection has rarely led to graft loss, it has been a great cause of morbidity and of significantly increased cost. In an attempt to decrease the acute rejection rate and related morbidity in SPK transplant recipients, we compared two "state-of-the-art" immunosuppression regimens in a prospective, randomized, single-center study. METHODS: Patients who received SPK transplants were randomized to receive either tacrolimus (TAC) and mycophenolate mofetil (MMF, n=18) or CsA (Neoral formulation) and MMF (n=18). All patients received OKT3 induction and prednisone, which was tapered to 5 mg/day by 6 months after transplantation. All rejection episodes were biopsy proven. In addition, metabolic control (HgbA1C, hypertension, serum cholesterol), drug toxicity, and infection also were measured. Data were compared with that of a historical group (n=18) who received conventional CsA (Sandimmune formulation) and AZA-based immunosuppression. RESULTS: The incidence of biopsy-proven acute rejection was 11% in both the TAC-MMF and CsA-MMF groups with only two patients in each group experiencing a rejection episode. This rejection rate was significantly decreased from that of the CsA-AZA historical group (77%, P<0.01). There were no significant differences in infection rates, including cytomegalovirus, or in metabolic control (HgbA1C, hypertension, and cholesterol levels). All patients remained on their initial immunosuppression regimen for the first 3 months after transplantation. Between 3 and 6 months after transplantation, three patients were switched from TAC to CsA for recurrent migraine headaches, posttransplant diabetes, and chronic cytomegalovirus infection. Two patients in the CsA-MMF group died of nonimmunologic causes (aspiration pneumonia and arrhythmia) between 3 and 6 months after transplantation. CONCLUSIONS: The data from this study show that MMF treatment significantly decreases the incidence of biopsy-proven acute rejection in SPK transplant recipients compared with AZA-treated historical controls. In addition, we conclude that TAC and CsA (Neoral), when combined with MMF, yield similar, low acute rejection rates with similar graft function and metabolic control.     

SLS-irritated human skin shows no correlation between degree of proliferation and TEWL increase

Vascular endothelial growth factor (VEGF), a very important in the process of tumor angiogenesis, was chosen as a target in a study to determine whether manipulation of angiogenesis with antibody against VEGF may interrupt tumor growth and metastasis. Anti-VEGF antibody was obtained from immunized rabbits, purified on an affinity column, and identified as neutralized antibody by Mile's assay. IVTA2MA891, a murine spontaneous breast cancer with a high rate of metastasis in lung in TA2 x 615 F1 mice, was chosen as an animal model in this study, because of the high expression of VEGF in the primary tumor as well as in the lung metastatic tumor. The anti-VEGF antibody could inhibit growth of S180 sarcoma in a dose-dependent manner, and the inhibition rate could reach 41.0% with a dose of 200 microg mouse(-1) day(-1). Anti-VEGF antibody could inhibit tumor growth by 76.2% in nude mice bearing human gastric cancer (MGC 803). When anti-VEGF antibody was combined with 131I-3H11, a murine monoclonal antibody conjugated with 131I, only one of five nude mice developed tumor and 84.0% more inhibition of tumor growth was obtained in comparison with treatment by 131I-3H11 alone. The growth of the primary tumor was inhibited by 44.0% and the number and size of the metastatic foci in the lungs were reduced by 73.0% and 83.7% respectively in the animal model, with a high rate of metastasis in lung. The anti-VEGF antibody may be potentially useful for clinical treatment of cancer and metastasis.     

Corneal transplantation in antibody-deficient hosts

PURPOSE: To examine the role of donor-specific antibodies, with or without complement, in rejection of orthotopic corneal transplants by using mice as recipients in which the genes for the heavy chain of immunoglobulin or the third complement component have been eliminated by homologous recombination. METHODS: BALB/c corneas were transplanted into eyes of B-cell-deficient (n=17) or wild-type control C57BL/6 (n=30) mice and into eyes of complement (C3)-deficient (n=15) or wild-type control 129-C57BL/6 (n=13) mice. After surgery all grafts were evaluated over 8 weeks in a masked manner by biomicroscopy for signs of rejection. RESULTS: The rates of corneal transplant rejection were similar among B-cell-deficient and C3-deficient mice compared with rejection rates in their respective wild-type control subjects. This similarity applied to the time course of rejection and to cumulative survival rates. CONCLUSIONS: Neither donor-specific antibody nor the third component of complement play essential roles in acute rejection of orthotopic corneal allografts in mice.     

A study comparing mycophenolate mofetil to azathioprine in simultaneous pancreas-kidney transplantation

BACKGROUND: Mycophenolate mofetil (MMF; Cell-Cept) is a potent and selective inhibitor of B and T lymphocyte proliferation that has proven effective in reducing the incidence of acute rejection in cadaveric kidney transplant recipients in several randomized, blinded clinical studies. Because the frequency and characteristics of rejection episodes may be different and more severe after combined pancreas-kidney transplantation, we hypothesized that MMF would have a significant impact on pancreas-kidney rejection and graft outcome. Therefore, we compared the efficacy of MMF versus azathioprine (AZA) in cyclosporine-treated simultaneous pancreas-kidney transplantations. METHODS: A retrospective comparison of 358 consecutive primary SPK transplantations performed from 1990 to 1997 was conducted. Patients received either MMF (n=109, 3 g/day) or AZA (n=249, 2 mg/kg q.d.) in combination with cyclosporine-based immunosuppression. All patients received a quadruple-drug sequential induction protocol with either OKT3 or Atgam. Several outcome parameters, including patient and graft survival rates and frequency of rejection, were analyzed. RESULTS: MMF-treated patients demonstrated a markedly reduced rate of biopsy-proven kidney rejection (31 vs. 75% AZA, P=0.0001), clinically significant pancreas rejection (7 vs. 24% AZA; P=0.003), and steroid-refractory rejection (15 vs. 52% AZA; P=0.01). As a result, kidney and pancreas allograft survival was significantly better in MMF patients compared with AZA patients (2-year survival rates: kidney, 95 vs. 86%; and pancreas, 95 vs. 83%). Although surgical infections after transplantation were more frequent in MMF patients, MMF patients were more likely to have undergone enteric drainage. Importantly, we did not observe an increased incidence of any of the bacterial, fungal, or viral infections that typically plague immunosuppressed transplant recipients. CONCLUSIONS: This retrospective study demonstrates that MMF is a highly effective immunosuppressant in SPK transplantation. It is not associated with an increased risk of opportunistic infections when a balanced immunosuppressive management approach is used. MMF strikingly reduces the frequency of acute cellular and steroid-resistant rejection. As a result of this combined experience, it is not unexpected then that we observe significantly improved graft survival rates in MMF-treated SPK patients compared with patients receiving a more traditional immunosuppressive regimen.     

Effect of adenosine metabolites on methyltransferase reactions in isolated rat livers

As introduction to a light- and electron-microscopial examination of rejected human corneal grafts a summary is given of the clinical signs of rejection. It is extremely important to recognize these signs in time and to initiate the correct therapy. Most failures in corneal transplantation are due to rejection. Rejection reactions are often not recognized early enough. The differential diagnosis is difficult because so many factors can trigger off a rejection. As the diagnosis is so often missed it is a good thing to consider the clinical picture of graft rejection once more. Maumenee: 'most ophthalmologists do not recognize the signs of early graft failure and usually do not refer the patient back for therapy until considerable oedema has developed from endothelial destruction' (1962). In the cases with a good prognosis the rejection percentage is plus or minus 12%; in vascularized corneas and complicated corneal transplantations as high as 75% (Polack, 1977).     

Effect of cytomegalovirus on an experimental model of chronic renal allograft rejection under triple-drug treatment in the rat

BACKGROUND: Cytomegalovirus (CMV) infection is thought to be a risk factor of chronic rejection. In clinical studies and animal models, mainly concerning graft vasculopathy, CMV has been demonstrated to enhance allograft arteriosclerosis. In this study we have investigated the effect of CMV on the early inflammatory response and graft histology in an experimental model of renal transplantation in a rat strain combination that develops chronic rejection under triple-drug immunosuppression. METHODS: Renal transplantations were performed in a rat strain combination of DA-->BN receiving triple-drug treatment (2 mg/kg methylprednisolone, 2 mg/kg azathioprine, 5 mg/kg cyclosporine daily subcutaneously). One group of immunosuppressed animals was infected with rat CMV, the Maastricht strain (10(5) plaque-forming units intraperitoneally), and the other group was left uninfected. As a positive control for alloresponse, one group of recipients received neither immunosuppression nor virus. Syngenic transplantations with triple-drug treatment and CMV were used as negative controls. The grafts were monitored by frequent ultrasound-guided fine-needle aspiration biopsies, and the intragraft inflammation was quantified in detail by the increment method and expressed in corrected increment units (CIU). Graft histology was performed in parallel. RESULTS: Nonimmunosuppressed animals developed acute rejection with a high peak of inflammation (7.9+/-3.2 CIU), a typical blast response, and lymphocytosis followed by infiltration of macrophages and necrosis within 7 days. Triple drug-treated animals had a short, mild inflammatory response (3.3+/-1.4 CIU at the peak) in the graft 3-5 days after transplantation but ended up with histological changes characteristic of chronic rejection with vasculopathy and fibrosis 40-60 days later. Triple drug-treated animals with CMV demonstrated a significantly stronger inflammation (4.5+/-1.8 CIU, P<0.01) than those without, and lymphoid activation continued longer and was followed by infiltration of macrophages in the graft. CMV infection of the graft was demonstrated by viral culture and antigen detection. In histology, chronic rejection with intimal thickening of arteries and arterioles and medial necrosis of large arteries was seen at 14 days, ending up with remarkable graft fibrosis within 20 days after transplantation. CONCLUSION: CMV prolonged and increased graft inflammation and accelerated chronic rejection of renal allografts under triple-drug treatment.     

Determinants of graft survival after renal transplantation

We studied multiple determinants of graft survival at a single center and the effects of nonimmunologic graft loss on transplant survival. This retrospective study examined the results of 589 cadaver donor transplants performed between 1986 and 1992. Graft survival rates were calculated using Kaplan-Meier estimates for both overall graft survival (all causes of graft loss) and immunologic graft survival (function lost due to acute or chronic rejection and noncompliance). Cadaver graft survival was significantly poorer with an increasing degree of DR mismatch (P=0.02). An analysis of pretransplant variables showed graft loss risk was highest with greater DR mismatches, two B-antigen mismatch, higher donor serum creatinine, and younger recipient age. After transplantation, acute rejection was the most significant factor associated with long-term graft survival. Our data demonstrate a significant advantage for zero DR and one DR mismatch cadaver donor transplants, with excellent immunologic graft survival. This study suggests that a combination of immediate graft function, prevention of acute rejection by appropriate early immunosuppressive therapy, and acceptable DR match enhances cadaveric graft survival.     

Rat heart-aorta cluster transplantation: a novel model to study transplant rejection

The purpose of this study was to develop a microsurgical cluster model of heart plus entire thoracic aorta transplantation and to compare it to the isolated model of heart transplantation as a tool to study transplant rejection. Thirty-six syngeneic (DA x DA and Lew x Lew) and allogeneic (DA x PVG and DA x Lew) cluster heart-aorta transplants were compared to 43 syngeneic and allogeneic isolated heart grafts. Graft survival, recipient survival and histological data on myocardial and aortic tissues were assessed. There was no statistically significant difference in graft survival between the two models studied (P > 0.05). In the cluster transplants, the aortic component was spared the severity of acute rejection noted for the myocardial counterpart. In conclusion, the results demonstrated that the cluster model was technically feasible and highly reproducible. Additionally, it was possible to apply this model to the study of experimental allograft rejection using novel immunosuppressants. The success of the cluster model in strongly mismatched transplant strain combinations underscores its potential for application in slower rejection combinations, making it particularly suited for chronic rejection studies. The inherent capacity for sampling a broader range of vessel sizes in one animal makes the cluster model more suitable than the isolated models of aorta or heart for application to experimental protocols.     

Late acute rejection and subclinical noncompliance with cyclosporine therapy in heart transplant recipients

BACKGROUND: Although noncompliance with immunosuppressive medication is recognized as a critical behavioral risk factor for late acute rejection episodes and graft loss after transplantation, little is known about the degree of subclinical cyclosporine noncompliance, its associated risk for acute late rejection episodes (>1 year after transplantation), and its determinants in heart transplant recipients. METHODS: The convenience sample of this longitudinal study included 101 European heart transplant recipients (87 men and 14 women), with a median age of 56 (Q1 = 50, Q3 = 61) and a median posttransplantation status of 3 (range 1 to 6) years. Subclinical cyclosporine noncompliance was measured during a 3-month period with electronic event monitoring. Selected sociodemographic, behavioral, cognitive, emotional, health, and treatment-related determinants of medication noncompliance were measured by using instruments with established psychometric properties or by patient interviews. With the use of iterative partitioning methods of cluster analysis, including nonstandardized electronic event monitoring compliance parameters, patients were categorized by degree of subclinical cyclosporine noncompliance into a 3-cluster solution. RESULTS: Overall compliance was high, with a median medication taking compliance of 99.4%. The 3 derived clusters, that is, excellent compliers (84%), minor subclinical noncompliers (7%), and moderate subclinical noncompliers (9%), differed significantly by degree of subclinical noncompliance (p < .0001) and showed a 1.19%, 14.28%, and 22.22% incidence of late acute rejections (p = .01), respectively. The 3 groups also differed in terms of former medication noncompliance (p = .02), appointment noncompliance (p = .03), and perceived self-efficacy with medication taking (p = .04). CONCLUSIONS: Although in absolute numbers cyclosporine compliance in this sample was high, minor deviations from dosing schedule were associated with an increased risk for acute late rejection episodes. This suggests a pivotal role of patient compliance in successful long-term outcome after transplantation.     

Dual pathways of tubular morphogenesis of vascular endothelial cells by human glioma cells: vascular endothelial growth factor/basic fibroblast growth factor and interleukin-8

In this study, we examined whether human glioma cells are angiogenic in a model using human microvascular endothelial cells, and also which factor is responsible for the glioma-dependent angiogenesis. Tubular morphogenesis in type I collagen gel by human microvascular endothelial cells was stimulated in the presence of 10 and 100 ng/ml of vascular endothelial growth factor (VEGF), 10 ng/ml basic fibroblast growth factor (bFGF) and 10 ng/ml of interleukin-8 (IL-8). Tube formation of the microvascular endothelial cells was assayed in the glioma cell lines IN157 and IN301, co-cultured using the double chamber method. IN301 cells had much higher levels of VEGF, bFGF and transforming growth factor-beta mRNA than IN157 cells, whereas the two had similar levels of transforming growth factor-alpha mRNA. By contrast, IN157 cells had much higher levels of IL-8 mRNA than IN301 cells. IN301-dependent tubular morphogenesis was inhibited by anti-VEGF or anti-bFGF antibody, and the inhibition was almost complete when anti-VEGF and anti-bFGF antibodies were present. On the other hand, IN157-dependent tubular morphogenesis was inhibited by anti-IL-8 antibody, but not by anti-VEGF or anti-bFGF antibodies. These findings demonstrated dual paracrine controls of tumor angiogenesis by human glioma cells. One is mediated through VEGF and/or bFGF, and the other, through IL-8.     

Low level of interleukin 10 synthesis during liver allograft rejection

Interleukin 10 (IL-10) is a macrophage and T-cell-derived cytokine with potent immunosuppressive properties. To assess its role in liver allograft rejection, we evaluated the plasma level and in situ production of IL-10 after liver transplantation and designed in vitro studies to asses the effects of IL-10 on the allogeneic response. Normal controls and liver transplant recipients with acute rejection, chronic rejection, other complications (recurrent hepatitis C, biliary complications), or no complications were evaluated. The plasma IL-10 level was measured by an immunoenzymatic technique. IL-10 expression in the liver was detected on frozen liver biopsies by in situ hybridization and immunohistochemistry. Plasma IL-10 levels were not elevated during acute or chronic rejection, when compared with liver recipients with uncomplicated transplants. IL-10 mRNA and protein expressions in the liver graft were restricted to rare scattered sinusoidal cells of transplant recipients with acute or chronic rejection, as well as in those with no complications. In mixed lymphocyte cultures performed with peripheral blood mononuclear cells (PBMC) from normal subjects, IL-10 decreased the cell proliferation in a dose-dependent manner, and this immunosuppression was synergistic with that of cyclosporine or FK506. These findings indicate that IL-10 production is low during allograft rejection. Thus, IL-10 therapy in association with cyclosporine or FK506 might be proposed after liver transplantation.     

Pancreas and islet transplantations

Pancreas transplantation has been established as a treatment option for type I diabetes mellitus with one-year patients survival rate of 91% and one-year graft survival rate of 71%. Simultaneous pancreas and kidney transplantation with the bladder-drainage technique is most frequently performed. The bladder drainage technique makes amylase activity measurement in the urine as well as urine cytology possible, which facilitate a diagnosis of acute rejection. Combination treatment with cyclosporine, azatioprine, steroid and anti-lymphocyte globulin is usually employed for immunosuppression. In addition, FK506 in now available and expected to contribute to better graft survival. In contrast, islet transplantation has not yet achieved satisfactory results. Although a large number of islets can now be obtained from one pancreas, they are not sufficient for stabilizing a diabetic condition and multiple donors are still required. Xeno-transplantation may resolve the problem. Both pancreas and islet transplantation will achieve better results with further advance of transplant techniques including immunosuppressive treatment and diagnostic methods for acute rejection.     

The pattern of disulfide linkages in the extracellular loop regions of connexin 32 suggests a model for the docking interface of gap junctions

This study evaluated the contribution of acute parenchymal rejection and interferon (IFN)-gamma to the development of graft arterial disease (GAD) in totally allogeneic murine cardiac transplants. BALB/c (H-2d) hearts were transplanted into wild-type C57BL/6 (B6, H-2b) or B6 IFN-gamma-deficient (GKO) recipient mice. Assessing the role of acute parenchymal rejection in the GAD process involved two different immunosuppression protocols using anti-CD4 and -CD8 monoclonal antibodies (MAbs): virtually complete long-term immunosuppression (denoted as complete immunosuppression) was achieved by administering both MAbs 6, 3, and 1 day before transplantation and weekly thereafter; in contradistinction, a single, early, transient episode of rejection (transient rejection) was attained by administering MAbs beginning 4 days after transplant and then at weekly intervals. The extent and duration of T cell depletion under these two regimens were evaluated using flow cytometric analysis of peripheral blood lymphocytes. After a single injection of MAbs, peripheral blood CD4+ and CD8+ T cell depletion was approximately 98% at 1 week and approximately 88% at 2 weeks. After three injections (analogous to days 6, 3, and 1 before transplant), peripheral blood CD4+ and CD8+ T cell depletion was >98% at 2 weeks and approximately 87% at 4 weeks. Functioning cardiac allografts were removed at 8 and 12 weeks after transplant and analyzed by hematoxylin and eosin, elastic tissue, and immunohistochemical stains, and the severity of parenchymal rejection versus GAD was scored. With complete immunosuppression (antibody before and after transplant), BALB/c allografts showed little parenchymal rejection or GAD, suggesting that persistent depletion of T cells blocked subsequent development of GAD. However, even a single transient acute rejection episode allowed the subsequent development of GAD accompanied by augmented major histocompatibility complex (MHC) class II, VCAM-1, and ICAM-1 expression at 12 weeks; these allografts showed no residual CD4+ or CD8+ T cells. In comparison, allografts undergoing transient rejection in GKO recipients did not develop GAD, despite persistent macrophage and natural killer cell (NK) infiltrates comparable to those seen in wild-type recipients. Moreover, the arterioles of hearts transplanted into GKO recipients showed no or minimal increases in MHC class II, ICAM-1, and VCAM-1 relative to baseline expression. In conclusion, a single episode of allogeneic injury mediated by T cells suffices to evoke subsequent graft arteriosclerosis, even in the absence of additional T-cell-mediated injury, and the process appears to depend on IFN-gamma.     

Importance of T cells to accelerated rejection and acceptance of renal allografts in sensitized rat recipients

BACKGROUND: Sensitized recipients often experience fulminant allograft loss by yet ill-defined cellular and/or humoral immune mechanisms. In this study, we analyzed the contribution of cellular elements, in particular T cells, to the accelerated rejection of renal allografts in sensitized rats. METHODS AND RESULTS: LEW rats sensitized with BN skin grafts died of uremia in 3.3+/-0.9 days after transplantation of a BN kidney, similarly to bilaterally nephrectomized animals. Adoptive transfer of 10(6) graft-infiltrating mononuclear cells as well as their CD25+ subset into otherwise normal LEW recipients accelerated rejection of BN test cardiac allografts (5.4+/-0.5 days to 6.6+/-0.4 days vs. 7.8+/-0.8 days in controls, P<0.0007), while the CD25- population was ineffective (8.0+/-0.6 days, NS). Furthermore, alpha/beta-T-cell receptor (TCR)-targeted therapy with R73 monoclonal antibody abrogated accelerated rejection, and produced long-term survival in sensitized animals treated before kidney engraftment (day -7 to day -1). Long-term survival was associated with an up-regulation of intragraft interleukin-4 and interleukin-10 expression in conjunction with depressed Th-1-type cytokines. In addition, alpha/beta-TCR-targeted therapy even in low subtherapeutic dose decreased IgM alloantibody levels, and prevented the switch from IgM to IgG alloantibody response. CONCLUSIONS: This is the first report that documents the striking efficacy of alpha/beta-TCR-targeted therapy in sensitized rat renal transplant recipients. The results provide evidence for a critical role of T cells for both accelerated rejection and long-term graft survival. Up-regulation of Th2-type cytokine profile may, at least in part, contribute to the acquisition of immune unresponsiveness after alpha/beta-TCR-targeted therapy in this well-defined rat renal transplant model.     

Liver tumor targeting of drugs: Spherex, a vascular occlusive agent

In order to determine whether the donor-specific T cell allorepertoire evaluated in patients before transplantation can be predictive for kidney graft survival, a study has been set up in which the number and activation state of donor-specific T lymphocytes before transplantation were correlated to transplant survival time. Limiting dilution analysis assays were carried out to determine precursor frequencies of both T helper and cytotoxic T lymphocytes. The activation state of these cells was studied by evaluating the inhibitory capacity of cyclosporine on helper and cytotoxic T cells and/or a monoclonal antibody directed against CD8 on cytotoxic T cells. This study shows that neither a significant difference in the number nor activation state of donor-directed helper and cytotoxic T cells before transplantation could be detected when patients who acutely rejected their grafts were compared with patients who still had a well-functioning kidney graft after more than 10 years. Moreover, no significant differences in the donor-specific T cell repertoire were found when patients who had been subject to multiple rejection episodes were compared with patients who experienced few complications after transplantation. Therefore, we conclude that in individuals who have not been sensitized to HLA antigens of the donor, the donor-specific peripheral T cell allorepertoire prior to transplantation is not predictive of kidney graft survival.