Absence Of Rejection Research Articles

T-Cell autoreactivity to Hsp in human transplantation may involve both proinflammatory and regulatory functions

Heat shock proteins (Hsp) are moving from the category of basically intracellular chaperone molecules to important proteins in both innate and acquired immune responses, with great potential for clinical application as immunomodulators. Both proinflammatory and regulatory Hsp-reactive T cells have been described in animal models of autoimmune diseases. To investigate the role of autoreactivity to Hsp60 and Hsp70 in human transplantation, we analyzed, sequentially, peripheral blood mononuclear cell proliferation and cytokine production before and at different time points after renal transplantation, as well as the modulation of proliferation to Hsp in the presence of exogenous cytokines. Proliferation to Hsp60 and Hsp70 in the pretransplantation (pre-Tx) period was significantly associated with rejection episodes in the first months post-Tx. In contrast, IL-4 production was significantly associated with absence of rejection. Addition of exogeneous IL-4 distinctly modulated the proliferative response to Hsp60; inhibiting proliferation in 83% of patients in the early post-Tx period (0–6 months), in which rejection episodes occurred, and inducing proliferation in 62.5% of patients in the later period (> 12–24 months), when no rejection was observed. Characterization of autoreactive anti-Hsp60 regulatory T cells may permit new approaches to control the proinflammatory response to the graft, as well as aggressive autoimmunity.

The avidity of allospecific cytotoxic T lymphocytes (CTL) determines their cytokine production profile.

Donor-specific CTL present within the cardiac allograft during a rejection episode are distinct from those that populate the cardiac allograft in the absence of rejection. Whereas the former generally have a high avidity for donor cells, the latter mainly have a low avidity for donor cells. This observation made us reason that high-avidity CTL are implicated in transplant rejection, whereas low-avidity CTL are not. In the present study, we analyse whether both CTL subsets were distinct with respect to their IL-2, IL-4, IL-6 and interferon-gamma (IFN-gamma) secretion pattern. CTL clones with either a high or a low avidity for donor antigens were stimulated with donor cells, third party cells, or immobilized anti-CD3 MoAb and the amount of cytokine released was measured. High- and low-avidity CTL clones were found to differ with respect to their IFN-gamma production profile. Stimulation with donor cells resulted in IFN-gamma secretion by high-avidity CTL clones, but not by low-avidity CTL clones. CD3 stimulation, in contrast, led to secretion of equivalent amounts of IFN-gamma by both CTL subsets. These observations indicate that low-avidity CTL are fully capable of producing IFN-gamma, but, in contrast to high avidity CTL, fail to do so when they encounter donor cells. As IFN-gamma favours the occurrence of transplant rejection, this observation emphasizes the relevance of high-avidity CTL in the rejection process. Additionally, the data show that the cytokine production profile of CTL depends on the nature of the stimulus.

Computerized heart allograft-recipient monitoring: a multicenter study.

Computerized heart allograft recipient monitoring (CHARM) is a unique concept of patient surveillance after heart transplantation (HTx), based on the evaluation of intramyocardial electrograms (IEGMs) recorded non-invasively with telemetric pacemakers. Previous open, single-center studies had indicated a high correlation between CHARM results and clinical findings. The present study was initiated to assess the suitability of CHARM for monitoring the absence of rejection in a blind, multicenter context. During the HTx procedure, telemetric pacemakers and two epimyocardial leads were implanted in 44 patients at four European HTx centers. IEGMs during pacing were recorded and transferred via the Internet to the CHARM computer center, for automatic data processing and extraction of diagnostically relevant information, i.e., the maximum slew rate of the descending part of the repolarization phase of the ventricular evoked response (VER T-slew). The study period comprised the first 6 months after HTx, during which the transplant centers were blind to the CHARM results. A single threshold diagnosis model was prospectively defined to assess the ability of the VER T-slew to indicate clinically significant rejection, which was defined as an endomyocardial biopsy (EMB) grade greater than or equal to 2, according to the grading system of the International Society for Heart and Lung Transplantation. All EMB slides from three centers were reviewed blind by the pathologist of the fourth center in order that agreement among the histological diagnoses at the various centers could be assessed. Totals of 839 follow-ups and 366 EMBs were obtained in 44 patients. Thirty-seven patients were alive at the end of the study period. Age at HTx, EMB grade distribution, and rejection prevalence varied significantly between the centers. Review of the EMB results showed considerable differences with respect to classification of significant rejection. Comparison of average VER T-slew values with and without rejection in the 15 patients who exhibited both states revealed significantly lower values under the influence of rejection (97+/-13% vs 79+/-15%, P<0.0001). Twenty out of the 25 cases with significant rejection were correctly identified by VER T-slew values below a threshold of 98% (sensitivity =80%, specificity =50%, negative predictive value =97%, positive predictive value =11%; P<0.0005). Of the EMBs, 48% could have been saved if the diagnosis model had been used to indicate the need for EMB. A high negative predictive value for the detection of cases with significant rejection has been obtained in a prospective, blind, multicenter study. The presented method can, therefore, be used to supplement patient monitoring after HTx non-invasively, in particular to indicate the need for EMBs. In centers with patient management similar to the ones who participated in the study, this may allow a reduction in the number of surveillance EMBs.

Renal function as a predictor of long-term graft survival in renal transplant patients.

Acute rejection is a major risk factor for kidney graft failure. However, as acute rejection has been progressively reduced by recent immunosuppressive regimens, other risk factors are becoming increasingly important. Evidence is accumulating that early renal function predicts long-term outcome. A recent registry survey of more than 100 000 kidney transplants found that 6- and 12-month serum creatinine levels, as well as the change between 6 and 12 months, are strongly associated with long-term graft survival. A survey of paediatric renal transplant recipients showed that poor creatinine clearance (<50 ml/min) as early as 30 days post-transplant predicted an annual rate of graft loss of 13% compared with <3% in patients with 30-day clearance >50 ml/min. This association between early renal function and long-term outcome was confirmed in multicentre studies. Renal transplant recipients (n=572) with 6-month serum creatinine levels >1.5 mg/dl suffered 3-year graft loss of 19.3% compared with only 8.5% in patients with levels <1.6 mg/dl (P<0.001). Significantly fewer patients receiving tacrolimus had 12-month serum creatinine levels >1.5 mg/dl compared with cyclosporin (42 versus 54%, P<0.05). Interestingly, a single-centre study (n=436) found that while glomerular filtration rate (GFR) at 6 months post-transplant had remained stable over the last decade, the rate of loss of renal function had decreased. A lower rate of GFR loss was associated with absence of rejection, use of mycophenolate mofetil rather than azathioprine and use of tacrolimus rather than cyclosporin (P<0.01). In conclusion, early measures of renal function allow identification of those patients at highest risk of graft failure and provide an invaluable tool for improving outcomes by tailored immunosuppression. The choice of such immunosuppression should be guided not only by its ability to prevent rejection, but also by its impact on renal function.

Granzyme expression in fine-needle aspirates from liver allografts is increased during acute rejection.

We investigated whether determination in fine-needle aspiration biopsy (FNAB) specimens of cells expressing granzymes (Grs) and Fas ligand would provide a reliable, easy, and quantitative measure of rejection activity in the transplanted liver. Retrospectively, 13 FNAB specimens obtained during clinical acute rejection, 10 FNAB specimens obtained during subclinical rejection, 12 FNAB specimens obtained during cytomegalovirus (CMV) infection, and 26 FNAB specimens obtained in the absence of rejection or infection were included on the study. Cytospin preparations of FNAB and peripheral-blood specimens were immunocytochemically stained for Fas-ligand and Gr, and increments in the liver were calculated by subtracting frequencies of positive cells in blood from those in FNAB specimens. Only sporadically Fas ligand-expressing, but many Gr-expressing, cells were detected in FNAB specimens. Increments in Gr-positive (Gr(+)) cells were significantly greater in FNAB specimens obtained during clinical rejection (median, 70 Gr(+) cells; range, 0 to 312 Gr(+) cells; P = .006) and tended to be greater in FNAB specimens obtained during subclinical rejection (median, 62 Gr(+) cells; range, 5 to 113 Gr(+) cells; P = .09) compared with those obtained in the absence of rejection (median, 16 Gr(+) cells; range, 0 to 103 Gr(+) cells). Increments obtained during clinical or subclinical rejection did not differ from those obtained during CMV infection (median, 27 Gr(+) cells; range, 6 to 212 Gr(+) cells). With the exclusion of specimens obtained during CMV infection, the sensitivity of Gr determination in FNAB specimens for the diagnosis of acute rejection (either clinical or subclinical) was 70%, and specificity, 69%. In FNAB specimens obtained during clinical and subclinical acute rejection episodes after liver transplantation, increased numbers of Gr-expressing cells were present; in the absence of CMV infection, their quantification provides a measure for rejection activity with moderate accuracy.

Molecular and immunohistochemical characterization of the onset and resolution of human renal allograft ischemia-reperfusion injury.

BACKGROUND Following allotransplantation, renal ischemia-reperfusion (I/R) injury initiates a series of events that provokes counter-adaptive immunity. Though T cells clearly mediate allospecific immunity, the manner in which reperfusion events augment their activation has not been established. In addition, comprehensive analysis of I/R injury in humans has been limited. METHODS To evaluate the earliest events occurring following allograft reperfusion and gain insight into those factors linking reperfusion to alloimmunity, we examined human renal allografts 30 to 60 minutes postreperfusion (n=10) and compared them with allografts with normal function that had resolved their I/R injury insult (>1 month posttransplant, n=6) and to normal kidneys (living donor kidneys before procurement, n=8). Biopsies were processed both for immunohistochemical analysis as well as for transcript analysis by real-time quantitative polymerase chain reaction (RT-PCR). RESULTS Reperfusion injury was characterized by increased levels of gene transcripts known to be involved in cellular adhesion, chemotaxis, apoptosis, and monocyte recruitment and activation. T-cell-associated transcripts were generally absent. However, recovered allografts exhibited increased levels of T-cell and costimulation-related gene transcripts despite normal allograft function. Consistent with these findings, the immediate postreperfusion state was characterized histologically by tubular injury and monocyte infiltration, while the stable posttransplant state was notable for T-cell infiltration. CONCLUSIONS These data suggest that monocytes and transcripts related to their recruitment dominate the immediate postreperfusion state. This gives way to a T-cell dominant milieu even in grafts selected for their stable function and absence of rejection. These data have implications for understanding the fundamental link between I/R injury and alloimmunity.

Histology predicts cirrhotic evolution of post transplant hepatitis C.

Hepatitis C recurring after orthotopic liver transplantation varies in severity and some patients rapidly develop fully established liver cirrhosis. Neither clinical nor biological markers of such rapid cirrhotic evolution are available. To assess the value of histology in identifying patients who will develop cirrhosis shortly after liver transplantation. Only cases of recurrent hepatitis C diagnosed by both hepatitis C virus-RNA positive serum and liver changes consistent with hepatitis, with no other causes of allograft injury, were considered. A total of 128 liver biopsies were scored from 29 consecutive patients with a mean follow up of 48 (13.97) months. The histological activity index was evaluated according to Ishak et al. The time of the first histological diagnosis of recurrent hepatitis C in the absence of rejection was defined as time of histological recurrence (RHC-T). First histological diagnosis of recurrent hepatitis with no features of rejection was obtained at the six month biopsy in 23 of 29 cases. By the end of follow up, nine patients had developed cirrhosis (mean follow up 38 (14.39) months (range 18-60)). The remainder (mean follow up 46 (13.40) months (24-72)) showed a spectrum of fibrosis but no cirrhosis. Severe necroinflammatory lesions at RHC-T significantly correlated with rapid development of cirrhosis. At the RHC-T biopsy, only cases evolving into cirrhosis showed confluent necrosis. The median value of the histological activity index was 11 (mean 11.11 (1.76) (range 9-14)) in patients who developed cirrhosis and four (mean 4 (1.78) (range 1-8)) in the others (p<0.0001). A histological activity index > or =9 was associated with rapid development of cirrhosis in 100% of cases. After liver transplantation, the histological activity of recurrent hepatitis C predicts the risk of development of cirrhosis. By adopting Ishak's scoring system, a histological activity index > or =9 was 100% sensitive/specific in identifying subjects who rapidly developed cirrhosis.

Islet xenograft rejection in absence of CD8 + T cells does not require either interferon-γ or interleukin-5

We recently demonstrated that interleukin-5 and eosinophils mediate rejection of skin allografts when CD8 + T cell-dependent and Th1-type CD4 + T cell-dependent pathways are not functional. The purpose of this study was to determine whether a similar mechanism might be operative during rejection of rat islet xenografts in mice. First, we observed that eosinophils indeed infiltrate rejected islet grafts together with CD4 + and CD8 + T cells. CD8 + T cell depletion significantly enhanced graft survival and a further prolongation of islet function was obtained in combination with interferon-γ neutralization. However, islet rejection characterized by prominent eosinophil and macrophage infiltration still occurred in this setting. Although eosinophil infiltrates were dramatically reduced in interleukin-5 deficient mice, the ability of these animals to reject islet xenografts under CD8 + T cell depletion and interferon-γ neutralization was similar to that of wild-type mice. We conclude that in absence of CD8 + T cells and interferon-γ, macrophages, but not eosinophils, mediate rejection of rat-to-mouse islet xenografts.

Can a Transplanted Living Donor Kidney Function Equivalently to its Native Partner?

Early renal functional adaptation was examined in 81 haploidentical donor and recipient pairs, as well as long-term stability of glomerular filtration rate (GFR) in 78 recipients. GFR was determined pre- and 1 month postnephrectomy in donors and 1 month post-transplant and yearly thereafter in recipients. Compensatory increase in filtration (CIF) of transplanted and native kidneys was calculated using donor pretransplant GFR: [CIF = (GFR at 1 month/donor prenephrectomy GFR) × 100]. Annual rates of change in GFR were estimated using within-patient linear regression analysis (slopes). Recipients without rejection (n = 62) and their donors had similar early GFR and CIF. Those with acute rejection (n = 19) had significantly lower GFR and CIF than their donors (61 ± 16 mL/min/1.73 m2 and 57 ± 14% vs. 75 ± 11 and 69 ± 9; p = 0.01 and p < 0.001). Recipients without cyclosporine (n = 52) had 1 month GFR and CIF of 70 ± 14 and 67 ± 14 vs. 72 ± 11 and 69 ± 11 for their donors. Those with cyclosporine (n = 29) had 1 month GFR and CIF of 64 ± 14 and 62 ± 16 vs. 69 ± 12 and 67 ± 11 for their donors (p = 0.15 and 0.16). Comparison of median (25th, 75th) rates of change of GFR with and without acute rejection or cyclosporine did not demonstrate significant effects of either on stability of allograft function, although there was a trend towards greater loss of GFR in cyclosporine-treated patients [− 1.1 (−2.5, 0.8) vs. 0.0 (−1.8, 1.2) mL/min/1.73 m2/year, p = 0.47]. We conclude that, in the absence of rejection, the transplanted kidney maintains the same capacity for functional adaptation as its native partner. Therapy with cyclosporine does not significantly inhibit early physiological adaptation of renal transplants.

In vitro T cell proliferation from kidney allograft biopsies with unremarkable pathology: new strategies for an old problem.

Acute rejection of renal allografts is mediated by infiltrating alloreactive T cells. The goals of this study were to correlate T cell proliferation with rejection and to determine whether T cell proliferation in the absence of rejection would predict future rejection episodes. Toward this, kidney biopsies (n=100) were cultured in the presence of interleukin-2. Cultures were examined at 4, 24, and 48 hr for T cell proliferation. A strong correlation was observed between T cell proliferation at any time point and rejection. There was not a significant correlation between T cell proliferation in biopsies with no rejection and the occurrence of a rejection episode within 2 months. However, T cell proliferation after 4 hr was a better predictor of the occurrence of rejection within 2 months compared with observations after 24 and 48 hr. Therefore, a subgroup of patients with unremarkable biopsies but T cell proliferation may be at risk for rejection and warrant closer observation and possible tailoring of immunosuppression.

Expression of endothelial adhesion molecules and thrombomodulin in cardiac transplantation

Objective: To describe the pattern of endothelial cell activation (ECA) in the transplanted human heart. Methods: 39 donor hearts had trucut biopsies from the right (RV) and the left ventricles (LV) at: initial assessment of the donor, end of warm ischaemia and after 10 min. of reperfusion. In addition, heart transplant patients had follow up RV biopsies during rejection surveillance at 1 week, 1 month and 3 months postoperatively. Biopsies exhibiting rejection were excluded from the analysis. 6 of the patients were cystic fibrosis domino donors. Another 9 patients undergoing routine cardiac surgery served as controls. Psel, VCAM-1, Esel and thrombomodulin (Thr) were examined by immunohistology. Results: There was no difference between the RV and the LV at any of the intraoperative time points, but important time-dependent variations were seen. Psel, and VCAM-1 (but not Esel) are upregulated in brain-dead and in domino donors (p 0.01 for LV and p 0.005 for RV). Thr is reduced at the baseline in all hearts used for transplantation, and the depletion accentuates postoperatively (p 0.30 for LV and p 0.02 for RV). Psel is present in 85% of vessels throughout transplantation and decreases to cca. 60% post-transplant (p 0.001). VCAM-1 is present in 20% of vessels initially, decreases to 5% during storage (this fall is inversely correlated to the ischaemic time), increases to 47% at reperfusion and gradually decreases thereafter (p 0.001). Esel expression increases progressively from 15% initially to 45% at reperfusion and decreases postoperatively (p 0.001). Patients with donor organ failure did not have any specific pattern of ECA. However, there was a trend towards accumulation of clinical risk factors in this group. Recipients of aprotinin had reduced expression of Esel and VCAM-1 in the LV at reperfusion. Conclusion: Cardiac transplantation (including domino) is associated with marked ECA changes, with no difference between the two ventricles. The changes persist in the postoperative period even in the absence of rejection. Expression of ECA markers is influenced by aprotinin but is not predictive of donor organ failure.

Blood and alveolar lymphocyte subsets in pulmonary cytomegalovirus infection after lung transplantation.

BackgroundCytomegalovirus (CMV) pneumonitis has been shown to be associated with lymphocytic alveolitis after lung transplantation. In the present study, we investigated a series of bronchoalveolar (BAL) and blood samples, collected in the absence of rejection or acute infectious episodes. in order -1: to evaluate intra-alveolar cell population changes concomitant with CMV replication and -2: to reappraise the value of cell population analysis in the management of patients after lung transplantation.MethodsWe used flow cytometry to investigate modifications of lymphocyte subpopulations related to pulmonary cytomegalovirus infections in blood and BAL samples from a series of 13 lung transplant recipients. After exclusion of samples obtained during pulmonary rejection, bronchiolitis obliterans or acute bacterial infection, 48 blood and BAL samples were retained for analysis: 17 were CMV positive by shell-vial assay and 31 were CMV negative in blood and BAL.ResultsOur results demonstrate that pulmonary CMV infection is associated with a significant increase in the total lymphocyte population in BAL samples, but with minor modifications of the various lymphocyte subpopulations and a significantly higher absolute number of B lymphocytes in blood samples.ConclusionsCytomegalovirus pulmonary infection is accompanied by only minor changes in BAL lymphocyte subpopulations. The study of BAL lymphocyte subpopulations therefore appears to be of limited clinical value in the diagnosis of pulmonary CMV infection. However, increased blood B-lymphocytes seems to be a clinical feature associated with CMV infection.

CD40 signaling replaces CD4+ lymphocytes and its blocking prevents chronic rejection of heart transplants.

Chronic rejection remains the major obstacle to long term survival in heart transplant recipients. The cellular and molecular mechanisms that underlie chronic rejection are not known, and their discovery can form the basis of clinical intervention. Several investigators have suggested that the development of chronic rejection in solid organ transplants is dependent on help mediated by CD4(+) lymphocytes. Importantly, the mechanism through which help is provided has not been fully delineated in transplant rejection. Using a murine heterotopic heart transplant model without immunosuppression, this study defines the functional role of CD4(+) lymphocytes in chronic rejection. In an MHC class II-mismatched model, we demonstrate that chronic rejection was absolutely contingent on the presence of CD4(+) lymphocytes. Importantly, here we report that signaling through CD40 can replace the requirement of CD4(+) lymphocytes, demonstrated by the development of chronic rejection in CD4 knockout recipients treated with a CD40-activating mAb (FGK45). The return of rejection appears to be a CD8(+) lymphocyte-dependent process, noted by the absence of rejection in FGK45-treated recombinase-activated gene knockout (CD4(+) and CD8(+) lymphocyte-deficient) recipients. The CD40 signaling pathway works independently of B7-CD28 costimulation, as indicated by the development of severe chronic rejection in CD28 knockout recipients. Importantly, this study provides evidence that CD40 ligand-targeted therapies may prevent chronic rejection only in strain combinations where CD4(+) lymphocyte help is absolutely required.

Surveillance transbronchial lung biopsies: Implication for survival after lung transplantation

Objectives: We wished to determine whether early rejection after lung transplantation as assessed by surveillance transbronchial biopsy predicts for survival. Methods: Between 1990 and 1997, 96 consecutive patients had lung transplantation: 89 had a minimum 1-month follow-up. For 71 consecutive patients we have 1-year follow-up and for 69 patients we have the results of the first 3 biopsies. Cytomegalovirus status, bronchiolitis obliterans prevalence, and use of total lymphoid irradiation are noted. Biopsies were done at 1 week and 1, 3, and 6 months. Standard immunosuppression consisted of induction antilymphocyte globulin and high-dose methylprednisolone induction for 1 week and standard maintenance triple therapy. Acute rejection treatment was with pulse methylprednisolone. Bronchiolitis obliterans syndrome was treated with total lymphoid irradiation and a change to tacrolimus and mycophenolate. Blinded grading using International Society for Heart and Lung Transplantation classification was done retrospectively. Results: Survival at 1 month and 1, 2, and 3 years for the 96-patient cohort with 1-year follow-up was 93%, 74%, 62%, and 56%. Survival was not significantly different for subsets with rejection on any combination of the first 3 biopsies (1/3, 2/3, 3/3) or absence of rejection on the first 3 biopsies. Ninety-one positive biopsy results were graded. Eighteen of 71 patients had one or more moderate or severe rejection episodes without survival difference relative to the others. There was no statistically significant association between acute rejection on the first 3 surveillance biopsy results and bronchiolitis obliterans. Conclusions: Intensive induction and maintenance immunotherapy with surveillance transbronchial biopsies and aggressive treatment of acute rejection is associated with a survival similar to that of patients without early acute rejection. This regimen appears to uncouple the association between early acute rejection and bronchiolitis obliterans. Further study may elucidate this mechanism. (J Thorac Cardiovasc Surg 2000;119:27-38)

Th1/Th2 cytokines and ICAM-1 levels post-liver transplant do not predict early rejection.

Th1 derived cytokines IFN-gamma and IL-2, Th2 cytokine IL-4, and ICAM-1 have been implicated in liver allograft rejection. In order to determine whether monitoring of cytokine profiles during the first days post-liver transplant can predict early rejection we measured IFN-gg, IL-2, sIL-2 receptor, IL-4 and ICAM-1 in 22 patients, in plasma samples obtained within 4 h after liver perfusion (baseline) and between postoperative days (POD) 3-6. ICAM-1 and sIL-2R levels at POD 3-6 were significantly higher than at baseline but did not differ in presence or absence of rejection. Mean percentage increase of ICAM-1 levels was significantly lower in patients with Muromonab-C3 Orthoclone OKT3 (J.C. Health Care) (OKT3) whereas percentage increase of sIL-2R levels was higher in OKT3-treated patients. IFN-gamma levels at POD 3-6 increased from baseline while IL-4 levels were unchanged. Levels of IFN-gamma, IL-4 and their ratios did not correlate with rejection or immunosuppressive therapy. Thus, Th1/Th2 cytokine monitoring during the first week post-transplant does not predict early rejection and immunosuppressive therapy is the predominant factor affecting ICAM and sIL-2R levels after liver transplantation.

Segmental Porcine Pancreatic Autotransplantation as Model for Pancreas Preservation Studies Using Two Different Techniques for Vascular Reconstruction

Pancreatic segmental autotransplantation in the pig has been considered an attractive model to study several aspects of pancreas transplantation because of the absence of rejections related to the immune system. However, the frequent presence of anatomical variations in the vascular supply of the left pancreatic segment in the pig makes this model difficult, impairing the access for vascular flushing and revascularization in pancreatic autotransplantation. We assessed pancreatic vascular anatomy of 71 Landrace pigs: group I (G1, n = 32) transplanted after direct reconstruction of the hepatic flow; and group II (G2, n = 39) transplanted after hepatic-celiac arterial reconstruction (HECAR) with an iliac vascular graft between the celiac trunk and the hepatic artery. HTK (histidine-tryptophan-ketoglutarate; Custodiol) and UW (University of Wisconsin; Viaspan) solutions were used. In total, 23 technically successfully transplanted animals (HTK = 15; UW = 8) after 24 h of cold storage were studied. Reconstruction time was longer in G2 than in G1 (p = .04). Thrombosis of the reconstructed hepatic artery occurred more in G1 than in G2 (45% vs. 8%, respectively, p = .013). Pancreatic arterial thrombosis was noticed in 10 animals in G1 (32%) and in 2 in G2 (5%) (p = .026). Ninety-four percent of pancreas grafts were suitable for cold storage study in G2 versus 45% for G1 (p < .001). No differences were noticed in K values, weight of transplanted grafts, preoperative and 24 h postoperative glycemia, for both preservation solutions. Segmental pancreatic autotransplantation can be successfully performed for cold preservation studies. A high percentage of pancreas useable for transplantation can be achieved using hepato-celiac arterial reconstruction. HTK solution is suitable for flushing and 24 h of preservation for pancreatic grafts in the porcine model.

Effects of graft-versus-host reaction on intrahepatic islet transplants.

The use of donor-specific bone marrow transplantation might represent a valuable approach for the induction of hyporesponsiveness to concurrent allogeneic organ and tissue grafts. In this setting, the occurrence of subclinical forms of graft-versus-host reaction (GVHR) can seldom be formally ruled out. When systemic administration of donor-specific bone marrow is performed together with intraportal transplantation of islets of Langerhans, GVHR might damage the implanted islets through an innocent bystander mechanism. The liver is, in fact, a prominent target of GVHR, and islets are sensitive to the noxious effects of proinflammatory mediators, including selected cytokines produced during GVHR. A parent (Lewis) to F1 (Lewis x Brown Norway) splenocyte transfer model was used to induce GVHR in rats. Islets were also obtained from Lewis donors and implanted into F1 recipients to examine the effects of GVHR on islet function in the absence of rejection. Selected doses of splenocytes were infused in F1 recipients to induce GVHR. When 150 x 10(6) cells were administered, all recipients developed clinical lethal GVHR. When 100 x 10(6) or 80 x 10(6) cells were given, lethal GVHR was observed in 40 and 20% of the F1 animals, respectively. A transient clinical syndrome occurred in the remaining animals and spontaneously subsided; histological findings consistent with persistent low-grade GVHR were observed in these animals at the time of death several months after splenocyte inoculation. When simultaneous splenocyte infusions and islet grafts were performed in chemically diabetic animals, no adverse effect of either clinical or subclinical GVHR was observed on islet function. Blood glucose profiles were normal, as were intravenous glucose tolerance test profiles. In conclusion, GVHR does not seem to adversely influence function of islets of Langerhans implanted intrahepatically in this parent to F1 experimental model.

Regional wall motion and strain of transplanted hearts in pediatric patients using magnetic resonance tagging.

Abnormal ventricular systolic torsion is present during histological rejection in adult cardiac transplant patients. Because biomechanical properties of transplanted hearts in the baseline state have not been studied in children, pediatric patients were evaluated to quantify ventricular wall motion and strain. Eight transplant studies and eight normal controls were evaluated. Magnetic resonance tagging was performed to determine radial shortening, twist, and strain in four ventricular anatomic areas at two short-axis levels. Controls had counterclockwise twist. Six transplant studies had clockwise twist, six had akinetic regions, and all had regions of no twist. One demonstrated paradoxical motion of the septum. A comparison between transplant patients and controls revealed strain to be similar in all regions except one (superior wall at the atrioventricular valve level) and strain distribution to be different only in two of eight regions. Pediatric transplant patients demonstrate regional wall motion abnormalities in the absence of rejection. Compared with normal controls, the transplanted left ventricle maintains normal strain in the presence of abnormal twist. This may be a compensatory mechanism and have clinical implications.

Transplant surgery injury recruits recipient MHC class II-positive leukocytes into the kidney

CD4 T cells, which are stimulated by the "indirect pathway" of antigen-presentation, participate in rejection. These T cells are sensitized by recipient major histocompatibility complex (MHC) class II-positive leukocytes that migrate into the transplant. Therefore, an important early step in rejection is the immigration of these recipient MHC class II-positive leukocytes into the renal transplant. The regulation of this early step is not understood. We now test the hypothesis that such leukocytes immigrate into the renal transplant in response to ischemic injury occurring during the transplant procedure. We transplanted Brown Norway (BN) kidneys into F1 Lewis/Brown Norway (L/BN) recipients. The F1 recipients are tolerant to the parental BN antigens, and any infiltration of recipient MHC class II-positive leukocytes results from injury occurring during transplantation surgery. In addition, ischemia/reperfusion injury was also induced by temporarily occluding the native renal arteries for 30 minutes. Transplanted kidneys and native kidneys, which suffered ischemia/reperfusion injury, were studied by immunohistochemistry on days 3, 7, 14, and 28 after surgery. Staining by the new monoclonal antibody (mAb) OX62 and antibodies to MHC class II identified dendritic cells. In addition, the following monoclonal antibodies identified: gamma/delta T cells, V65; B cells, OX33; cells that may be macrophages, dendritic cells, or dendritic cell precursors, ED1 (+) and OX62 (-); and recipient class II MHC, OX3. After transplantation, the serum creatinine increased to 4 mg/dl and then decreased, which was consistent with reversible injury during transplantation and the absence of rejection. We found that the injury of transplantation itself resulted in the infiltration of recipient MHC class II-positive leukocytes into the transplanted kidney. This infiltrate peaked at days 7 to 14 after surgery. The inflammation was peritubular and patchy and involved cortex and outer medulla. Double staining for OX62 and OX3 identified some of the infiltrating leukocytes as dendritic cells. Other recipient leukocytes were MHC class II positive, ED1 positive, and OX62 negative. We also found that MHC class II leukocytes, including dendritic cells, infiltrated native kidneys injured by ischemia/reperfusion injury. To our knowledge, this is the first demonstration that injury to the kidney during transplantation recruits recipient MHC class II-positive leukocytes into the kidney. Some of these leukocytes are dendritic cells.

Metallothionein: localization in human transplant endomyocardium, relation to cytokines and allograft function

Background: The aim of this study was to investigate the role of metallothionein in cardiac transplants in relation to cytokines and allograft function. Recent studies have revealed an association of allograft dysfunction with elevated proinflammatory cytokines independent of cellular rejection. In animal experiments, cytokines induced overexpression of metallothionein, a low–molecular-weight protein implicated in cellular stress response. Methods In 105 consecutive biopsies from 15 patients during the first 3 months after heart transplantation, metallothionein expression was investigated immunohistochemically. Its relation to serum interleukin-6, tumor necrosis factor-α, interleukin-2 (IL-2), soluble interleukin-2 receptor rejection, and echocardiographic parameters was determined. Forty-three biopsies of 12 patients with idiopathic ventricular tachycardia served as controls. Results Metallothionein expression was demonstrated in small vessels, cardiomyocytes, fibrocytes, and interstitial round cells. A positive relation between interleukin-6 levels and the number of metallothionein-positive small vessels ( p < 0.028) was observed. Patients with lower serum IL-2 levels showed significantly higher numbers of metallothionein-positive small vessels ( p < 0.043). Grafts with prolonged ischemic time (>150 minutes) showed a significantly higher myocardial metallothionein score ( p < 0.021). Metallothionein expression was associated with lower fractional shortening, larger left ventricular end-systolic diameter, and lower mean arterial pressure but not with acute cellular rejection. Conclusions Metallothionein expression is associated with elevated interleukin-6 and decreased interleukin-2 serum levels and left ventricular allograft dysfunction in the absence of rejection.