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Background: Low-molecular-weight heparin (LMWH) has been shown to prolong survival of rat cardiac allografts independently from immunosuppressive treatment. Furthermore, long-term treatment reduces the development of chronic graft vascular disease after experimental heart transplantation. The aim of the present study was to determine whether treatment with the LMWH reviparin has a beneficial effect on chronic rejection in a rat renal allograft model., Methods: Kidneys of Fisher (F344) rats were transplanted into unilaterally nephrectomized Lewis (LEW) recipients. LEW-->LEW isografts served as controls. Animals were treated with cyclosporine (5 mg/kg/d) for the first 10 days. Nephrectomy of the remaining kidney was performed after 10 days. Allografted animals were treated either with reviparin (2 mg/kg/d subcutaneously) for 24 weeks (Allo-24), from week 12 to 24 (Allo-12), or with vehicle for 24 weeks. Proteinuria was determined at regular intervals. Kidneys were harvested after 24 weeks for histomorphological and immunohistochemical evaluation., Results: No major bleeding complications were observed in reviparin-treated animals. Proteinuria was significantly reduced in allografted animals both by early as well as by late-onset treatment with reviparin. Transplant glomerulopathy was diminished in Allo-24 and in Allo-12 groups compared to vehicle-treated animals, whereas tubulointerstitial inflammation was influenced only in animals immediately treated with reviparin. Immunohistochemical studies demonstrated a marked reduction of renal monocyte and T-cell infiltration as well as expression of MHC II by treatment with reviparin., Conclusions: Treatment with the LMWH reviparin significantly improved chronic renal allograft rejection in the F344-to-LEW rat model, both after early and late start of therapy. Although the exact mechanisms of this beneficial effect remain unclear, our data offer a potential new therapeutical approach for prevention of chronic allograft nephropathy.

A markedly increased expression of endothelin (ET)-1 has been observed in renal allografts with chronic rejection, one of the most common causes of kidney graft loss. In this study we investigated the effect of treatment with a combined ET-A/B-receptor antagonist on the course of chronic renal allograft rejection. Experiments were performed in the Fisher-to-Lewis rat model of chronic rejection. Lewis-to-Lewis isografts and uninephrectomized Lewis rats served as controls. Animals were treated with either the oral combined ET-A/B-receptor antagonist LU224332 (20 mg/kg/day) or vehicle. Animal survival, blood pressure, creatinine clearance, proteinuria, and urinary ET excretion were investigated for 24 weeks. Kidneys were removed for light-microscopic evaluation and immunohistochemical assessment of cell-surface markers. Treatment with LU224332 did not improve survival after 24 weeks (0.47 vs. 0.38; p > 0.05 by log-rank test), nor did it have an influence on blood pressure, creatinine clearance, or proteinuria. Combined ET-A/B-receptor blockade was associated with a reduction of expression of cell-surface markers for macrophages (EDI), T-cells (R73), and major histocompatibility complex (MHC) II (F17-23-2), but did not lead to an improvement of histologic changes of chronic allograft rejection. Our data show that blocking both ET-A- and -B receptors, in opposition to a previously published beneficial effect of selective ET-A blockade, does not prevent the progression of chronic renal allograft rejection and does not prolong survival in this model. Functional integrity of the ET-B receptor therefore seems to play an important role in the nephroprotection provided by selective ET-A-receptor antagonists in chronic renal allograft nephropathy.

Background: Data on a systematic correlation of specific pathomorphologic lesions in renal allograft biopsy specimens with clinical outcome parameters are crucial to determine the relevance of kidney biopsy findings after transplantation for graft prognosis. Specific histologic lesions of the revised Banff '97 classification were correlated with clinical follow-up data., Methods: The analysis was done on a series of 48 consecutive renal allograft biopsy specimens. Logistic regression was used to compare for response to rejection treatment dependent on histologic grading. Cox regression was applied to analyze the impact of the histologic findings on graft failure during ongoing follow-up., Results: Severity of acute rejection was statistically associated with unresponsiveness to antirejection treatment (odds ratio 2.39, 95% confidence interval 1.13-5.03) and predicted an increased risk of graft failure (hazard ratio 2.16, 95% confidence interval 1.48-3.14). Intimal arteritis (hazard ratio 1.85, 95% confidence interval 1.40-2.45) was the only determinate of a poor survival prognosis. Mean serum creatinine level and the need for antihypertensive drugs were significantly higher in the Banff I-III graded groups after 1 and 2 years of follow-up, whereas patients with borderline rejection were not significantly different from the control group., Conclusion: We confirmed a significant association between the revised Banff '97 classification and graft outcome. Intimal arteritis was the only significant predictor of a poor survival probability. The distinction of borderline rejection and Banff grade I rejection seems to be important from a prognostic point of view.

Background: Epidemiological data implicate that renal transplants from living unrelated donors result in superior survival rates as compared with cadaveric grafts, despite a higher degree of human lymphocyte antigen (HLA) mismatching. We undertook a center-based case control study to identify donor-specific determinants affecting early outcome in cadaveric transplantation., Methods: The study database consisted of 152 consecutive cadaveric renal transplants performed at our center between June 1989 and September 1998. Of these, 24 patients received a retransplant. Donor kidneys were allocated on the basis of prospective HLA matching according to the Eurotransplant rules of organ sharing. Immunosuppressive therapy consisted of a cyclosporine-based triple-drug regimen. In 67 recipients, at least one acute rejection episode occurred during the first month after transplantation. They were taken as cases, and the remaining 85 patients were the controls. Stepwise logistic regression was done on donor-specific explanatory variables obtained from standardized Eurotransplant Necrokidney reports. In a secondary evaluation, the impact on graft survival in long-term follow-up was further measured by applying a Cox regression model. The mean follow-up of all transplant recipients was 3.8 years (SD 2.7 years)., Results: Donor age [odds ratio (OR) 1.05; 95% CI, 1.02 to 1.08], traumatic brain injury as cause of death (OR 2.75; 95% CI, 1.16 to 6. 52), and mismatch on HLA-DR (OR 3.0; 95% CI, 1.47 to 6.12) were associated with an increased risk of acute rejection, whereas donor use of dopamine (OR 0.22; 95% CI, 0.09 to 0.51) and/or noradrenaline (OR 0.24; 95% CI, 0.10 to 0.60) independently resulted in a significant beneficial effect. In the multivariate Cox regression analysis, both donor treatment with dopamine (HR 0.44; 95% CI, 0.22 to 0.84) and noradrenaline (HR 0.30; 95% CI, 0.10 to 0.87) remained a significant predictor of superior graft survival in long-term follow-up., Conclusions: Our data strongly suggest that the use of catecholamines in postmortal organ donors during intensive care results in immunomodulating effects and improves graft survival in long-term follow-up. These findings may at least partially be explained by down-regulating effects of adrenergic substances on the expression of adhesion molecules (VCAM, E-selectin) in the vessel walls of the graft.

Background: Graft-infiltrating T-cell (GIC) lines cultured from biopsies obtained during acute renal allograft rejection exhibit donor-specific cytotoxicity toward proximal tubular epithelial cell (PTEC) lines cultured from corresponding biopsies. This system allows for study of the relative contributions of perforin/granzyme B (GrB)- and Fas ligand (FasL)-based cytotoxicity to killing of PTEC., Methods: Expression of perforin, GrB and FasL was analyzed by immunocytochemical staining of cytocentrifuge preparations of GIC lines cultured from 10 renal allograft biopsies. Specific inhibitors of the perforin/GrB- and FasL-based pathways were used in 51Cr release and apoptosis assays to determine their relative contributions to cytotoxicity of GIC lines toward corresponding donor PTEC lines., Results: Cells with a strong granular pattern were observed upon immunocytochemical staining of GIC lines with anti-perforin or anti-GrB monoclonal antibodies. A diffuse staining pattern was observed upon staining with anti-FasL polyclonal antibodies. Six of eight GIC lines cultured from biopsies with acute rejection showed cytotoxicity toward corresponding donor PTEC lines, whereas two GIC lines cultured from biopsies without rejection did not. Preincubation of cytotoxic GIC lines with concanamycin A, an inhibitor of the perforin/GrB-based pathway, caused inhibition of both lysis and apoptosis of PTEC. Inhibition was not observed upon incubation with monoclonal antibodies that inhibit Fas., Conclusions: The perforin/GrB-based pathway is mainly responsible for cytotoxicity of GIC lines toward corresponding donor PTEC lines, suggesting that this pathway predominates in tubular epithelial cell destruction by cytotoxic T lymphocytes during acute renal allograft rejection in vivo.

To examine the incidence of interstitial and vascular rejection in pancreas allografts and its impact on graft survival, we studied 36 percutaneous pancreas biopsies and 10 pancreas transplantectomy specimens from 32 patients who had undergone simultaneous pancreas-kidney transplantation. Interstitial rejection (IR) was predominantly found in the biopsies, while vascular rejection (VR) was most prominent in the transplantectomies. Pancreas graft survival was significantly decreased for pancreas graft that had suffered from vascular rejection when compared to those with only interstitial rejection. Potential rejection markers, i.e., serum amylase, glucose, creatinine, and urinary amylase, did not correlate with histological signs of rejection, although increased levels of serum amylase were, in all but one case, associated with rejection. We conclude that a percutaneous pancreas biopsy remains the most reliable method to determine pancreas rejection, and that by distinguishing between IR and VR, a pancreas biopsy may provide important diagnostic as well as prognostic information.

A maintenance immunosuppressive regimen of cyclosporine and steroids after renal transplantation has proven to be a successful policy to obtain long-term graft survival. However, serious side-effects are associated with this therapy; these include an increased risk for infections, cancer, and cardiovascular morbidity and mortality. Therefore, this pilot study was conducted to investigate the possibility of reducing the immunosuppressive load after transplantation. To this end, we tried to develop an in vitro assay to predict graft rejection after withdrawing steroids from the immunosuppressive therapy. Patients who had stable renal function at least one year after transplantation were randomly divided into a group that continued to receive standard immunosuppression of cyclosporine and steroids and a group to be withdrawn from steroid therapy, the latter group being the subject of the present study. Patients withdrawn from steroids were monitored closely and when a biopsy-proven rejection occurred, steroid treatment was reestablished. Blood was collected from patients preceding steroid withdrawal and at fixed time points thereafter. In case of suspected rejection, blood was also taken before biopsy, before steroid treatment was reestablished. In the in vitro limiting dilution analysis-assays cytotoxic T lymphocyte precursor frequencies directed against kidney donor HLA-antigens were determined, in the absence or presence of cyclosporine and several concentrations of prednisolone and the combination of these agents. Confirming earlier results, we found that the number of cyclosporine-resistant cytotoxic T lymphocytes increased prior to a rejection crisis, while they did not change or even decreased in patients who retained normal graft function after steroid withdrawal. More importantly, the results show that 10(-7) M prednisolone in vitro differentially affected donor-specific cytotoxic T lymphocyte precursor frequencies in patients who experienced a rejection crisis after steroid withdrawal, compared with those who remained to do well. This heterogeneity could be detected before the start of steroid withdrawal. Therefore, we conclude that the present data justify a prospective clinical trial to investigate the possible application of this in vitro assay to predict for which patients steroid withdrawal might be considered.

Background: Acute rejection is characterized histologically by infiltration of the interstitium by mononuclear cells. Monocyte chemoattractant protein 1 (MCP-1) has recently been identified as a monocyte chemotactic factor. This study examined the possible role of MCP-1 in renal transplantation., Methods: The concentration of MCP-1 in urine and serum of 19 renal transplant patients was investigated using an inhibition radioimmunoassay. The patients were divided into a non-rejection (NRj) and a rejection (Rj) group. Normal healthy volunteers were included as controls. Immunoperoxidase staining for MCP-1 and CD14, as a marker for macrophages, was performed in renal biopsies of transplant patients with rejection and six biopsies from histologically normal kidneys, as controls. The size of urinary MCP-1 was determined by gel filtration chromatography and in a number of fractions assessed for monocyte chemotactic activity using a modified Boyden chamber assay., Results: Urinary excretion of MCP-1 in the Rj group ranged between 250 ng/mmol Cr and 3148 ng/mmol Cr with a median of 612 ng/mmol Cr. This is significantly higher than the results in the NRj group, ranging between 47 ng/mmol Cr and 288 ng/mmol Cr with a median of 229 ng/mmol Cr. In the normal control group, urinary MCP-1 levels ranged between 38 ng/mmol Cr and 74 ng/mmol Cr with a median of 50 ng/mmol Cr. The fractional excretion of MCP-1, calculated on the basis of MCP-1 and creatinine clearances, was found also to be significantly higher in the Rj group as compared to the NRj group. However, there was no significant difference in the serum levels of MCP-1 between the Rj, NRj, and normal control group. The intensity of MCP-1 staining in tubular epithelial cells and the degree of CD14+ cells in the interstitium was significantly higher in renal allograft biopsies than in the normal kidneys. In addition, MCP-1 isolated from urine of renal transplant patients with rejection was filtered with apparent molecular weight of 13 kDa and 11 kDa. Both sizes are chemotactically active for monocytes., Conclusions: These data suggest that urinary excretion of MCP-1 can be used as a marker for the episodes of acute rejection. The increase of urinary excretion of MCP-1 most likely is the result of local production by tubular epithelia cells. MCP-1 produced locally may, at least in part, be responsible for the influx of macrophages into the interstitium during rejection.

Histological and immunohistochemical analyses were made of biopsy specimens from 50 consecutive patients who experienced putative graft rejection. The mean age of the patients was 44.5 years (range, 17-69 years) and 26 were men. There were 67 evaluable allograft specimens, which were grouped according to the histological diagnosis: group 1, acute tubulointerstitial rejection (n = 42); group 2, acute vascular rejection (n = 18); and group 3, diffuse thrombosis (n = 7). Over a follow-up period of 21-57 months, the mean number of rejection episodes was 1.7, 2.8, and 3.3 in groups 1, 2, and 3, respectively. Allograft loss occurred in 7 out of 30, 10 out of 16, and 4 out of 4 patients in groups 1, 2, and 3, respectively. The following histological parameters differed significantly (P < 0.05) among the groups: interstitial edema, congestion of peritubular capillaries, glomerular thrombosis, and glomerular ischemia (group 3 > group 2 > group 1). Interstitial bleeding was seen more often in group 2 and 3 tissues than in group 1 specimens (P < 0.01). Immunohistochemical analyses showed that vascular rejection was associated with WT14 staining for monocytes and macrophages around the tubuli and with interstitial deposition of complement factor 3. With regard to serology, positive anti-endothelial cell antibody-dependent cellular cytotoxicity was associated with vascular rejection and thrombosis of the graft in all patients tested, and with graft loss in 75%. Pre-existent positive anti-IgG immunofluorescence on peritubular capillaries in pretransplant biopsy specimens incubated with patient serum was found in only 3 of the 50 patients, but was associated with graft loss in 2 of the 3. Cytomegalovirus infection was associated with a higher percentage of graft loss. There were significant intergroup differences in panel reactive antibodies before transplantation (P < 0.001), with higher titers in groups 2 and 3. The findings in relation to interstitial rejection are compatible with cellular rejection, while the data on vascular rejection support a humorally mediated pathogenesis.

We propose that tissue-specific alloantigens are of importance in interstitial and vascular rejection. To study this hypothesis we took the following approaches: multivariate analysis on our database (N = 482) was performed, the specificity of T cells cultured from kidneys with rejection was analyzed, and non-anti-HLA antibodies reactive with endothelium were studied. First we observed that in a cohort study of 482 patients receiving a cadaveric renal allograft 76 (15.8%) patients developed vascular rejection and 115 (23.9%) developed interstitial rejection. The incidence of vascular rejection was increased in patients with delayed graft function, HLA-DR mismatches, a prolonged cold ischemia period, and previous transplantations. Next we examined 40 graft infiltrating cell (GIC) lines cultured from renal biopsies taken during rejection episodes. Thirteen GIC lines reacted in a donor-specific fashion to proximal tubular cells (PTEC) but not to donor splenocytes. These GIC recognize polymorphic tissue-specific peptides in the context of allo-MHC Class I. Finally, we studied if non-conventional allo-antigen systems on endothelial cells could be the target of the humoral immune response during vascular rejection. We found the endothelial monocyte (EM) system, and another system that is present on endothelial cells and platelets, which can be tested in an antibody-dependent cellular cytotoxicity assay (ADCC).

Chronic rejection of renal allografts is a major cause of late graft loss. However, time of onset, relation with acute early rejection episodes, and risk factors are largely unknown. We undertook a cohort study of 482 consecutive patients from a single center who received a cadaveric renal allograft between January 1983 and April 1991. During the first 3 months after transplantation, 76 (15.8%) patients developed vascular rejection and 115 (23.9%) developed interstitial rejection. One-year graft survival of patients without rejection, with interstitial rejection, and with vascular rejection was 87.8%, 87%, and 48.7%, respectively. Five-year graft survival was 73.5% for the group without rejection, 71.4% for patients with interstitial rejection, and 34.3% for patients with vascular rejection. The adjusted relative risk of graft loss was 4.92 (95% CI 3.25-7.43) for patients with vascular rejection and 1.27 (95% CI 0.80-2.02) for patients with interstitial rejection compared with patients without early rejection, taking the time dependency of the rejection events and prognostic factors into account. The incidence of vascular rejection was increased in patients with primary nonfunction (RR 1.69, 95% CI 1.01-2.84), with 1 HLA-DR mismatch (RR 2.38, 95% CI 1.44-3.93), with 2 HLA-DR mismatches (RR 3.24, 95% CI 1.25-8.42), with a prolonged cold ischemia time (RR 1.03, 95% CI 1.00-1.06 per hr), and with 1 or more previous transplantations (RR 1.76, 95% CI 1.01-3.07). Risk of developing vascular rejection was decreased in patients using CsA as compared with azathioprine (RR 0.41, 95% CI 0.24-0.67). Early vascular rejection, occurring within 3 months after transplantation, is the most important predicting variable of both early and late graft loss. Use of CsA, less HLA-DR mismatching, and a cold ischemia time of short duration possibly prevent the development of vascular rejection.

Several groups have reported that recipients of a simultaneous pancreas-kidney transplantation suffer from more kidney rejection episodes than do recipients of a kidney transplantation (1-6). However, it is not known whether this is interstitial rejection, vascular rejection, or both. In this study, the renal biopsies and transplantectomies of 45 pancreas-kidney and 48 kidney transplant recipients were evaluated for the presence of interstitial and vascular rejection. Furthermore, the influence of OKT3 induction therapy on rejection after pancreas-kidney transplantation was studied. Of the 45 pancreas-kidney recipients. 4 patients did not suffer from rejection during follow-up, 28 suffered only from interstitial rejection, and 13 suffered from vascular (with or without interstitial) rejection, whereas 12, 19, and 14 of the 48 kidney transplant patients had no rejection, interstitial rejection, or vascular (with or without interstitial) rejection, respectively. Three patients with a kidney transplant were treated for rejection although no biopsy was taken. In the pancreas-kidney group, 38 of the total of 149 biopsies and transplantectomies taken contained no rejection, 92 had interstitial rejection, and 19 had vascular rejection. In the kidney group, these values were 13, 41, and 25, respectively, of 79 biopsies and transplantectomies taken (P = 0.002). Five-year renal graft survival was 79% in the kidney group and 60% in the pancreas-kidney group. Renal graft survival rates differed significantly (P = 0.02). Renal graft survival and occurrence of rejection did not reach significance between pancreas-kidney recipients treated with OKT3 induction therapy and pancreas-kidney recipients receiving conventional triple therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal biopsies were performed 1 week following renal transplantation at a time without clinical evidence of rejection in 43 patients (13 females, mean age 48 years range 18-60 and 30 males, mean age 43 years range 17-59 years). Thirty-six biopsies were available for histological or immunohistochemical analysis. Immunohistochemical analyses were performed with monoclonal antibodies against leukocytes (CD45), monocytes (WT14), complement factor 3 (C3), T-cells (Leu4), T-cell receptor alpha beta and gamma delta, tumour necrosis factor alpha (TNF alpha), IL-2 receptor (IL2-R, TAC), intercellular adhesion molecule-1 (ICAM1) and HLA-DR. The slides were scored semiquantitatively with the observers having no knowledge of clinical or patient data. TNF alpha and IL-2R were also measured by quantative PCR. None of the studied parameters correlated to delayed graft function or graft loss. Histological analysis showed that both focal interstitial infiltrate (18/35) and tubular basement membrane disruption (11/35) were followed by a higher incidence of subsequent rejection (P = 0.03 and 0.02 respectively). Also positivity for WT14 around tubuli (P = 0.02) was associated with subsequent occurrence of rejection. The intensity of staining of ICAM-1 on PTC as well as TAC on proximal tubular cells was associated with the number of subsequent rejection episodes. The association between the IL-2 receptor and subsequent rejection was also found applying PCR to the tissue specimens. We conclude that the presence of focal interstitial infiltrates and tubulitis in 1-week biopsies from well-functioning grafts carries an increased risk of subsequent rejection.(ABSTRACT TRUNCATED AT 250 WORDS)

Lymphocytes have been used as the classic target cells to measure donor specific alloreactivity before and after renal transplantation. This was based on the concept that during rejection after kidney transplantation graft cells were recognized only because of sharing of alloantigens with lymphoid cells. There is, however, sufficient evidence to suggest that tissue specific recognition of proximal tubular cells and graft endothelial cells can occur by allospecific T cells and IgG antibodies, respectively. The antigens involved have not yet been well characterized, but seem to be of relevance in the pathogenesis of both interstitial and vascular rejection. Identification of the antigens involved may lead to more appropriate matching strategies.

Acute interstitial rejection is an important clinical problem after cadaver kidney transplantation. Recently we have reported that six of 17 graft-infiltrating cell (GIC) lines isolated from kidneys undergoing such rejection episodes recognize graft-derived proximal tubular cells but not lymphoid cells from the same donor. In this study we characterized the specificity of one such GIC line in more detail. From this T-cell line, 18 cytotoxic T-cell (CTL) clones were isolated. Four of these were also cytotoxic against donor lymphoid cells. Nine tissue-specific clones were selected for further analysis. They all contained CD8+ and TCR alpha/beta+ cells and cytotoxicity by these cells was class I restricted. Only proximal tubular epithelial cells (PTEC) expressing HLA-A31 (an antigen present in the donor but absent in the recipient) were recognized by all clones. There were, however, three clones that did not lyse all HLA-A31+ PTEC lines, demonstrating recognition of an HLA-A31 tissue-associated polymorphism. Thus during rejection episodes after renal transplantation GIC may recognize various tissue-derived peptides bound to a mismatched HLA molecule on the cell surface of renal parenchymal cells. These GIC are likely to contribute to the observed destruction of tubuli during episodes of acute rejection after kidney transplantation.

Acute rejection after renal allotransplantation is characterized by the presence of a mononuclear cell infiltrate in the interstitium with involvement of tubuli. In a previous study on renal histology we showed that tubular damage by graft infiltrating cells (GIC) is a sign of clinically significant rejection. We cultured proximal tubular epithelial cells (PTEC) and T cells bearing the interleukin 2 (IL-2) receptor from biopsies after transplantation. In vitro outgrowth of T cells from the biopsy was significantly (P = 0.0014) related to histological signs of graft rejection. Of the T cell lines generated from 25 biopsies, only five lines showed no or low cytotoxicity against donor PTEC. Three cell lines were cytotoxic towards donor PTEC, but not against PHA stimulated donor splenocytes, suggesting tissue specificity of GIC. Treatment of PTEC with interferon (IFN) gamma for 72 hours to upregulate MHC class I and to induce MHC class II expression did not necessarily result in an increased susceptibility to lysis. However, three PTEC lines displayed an increment of susceptibility to lysis after IFN gamma treatment. Analysis of one T cell line from the same graft revealed a high percentage of CD4 positive cells, compatible with a class II restricted cytotoxicity. This was confirmed by blocking experiments using anti-CD4, anti-CD8, anti-class I, and anti-class II antibodies. Blocking experiments were done with 12 of these 25 lines. Anti-CD3 and anti-CD18 antibodies inhibited cytotoxicity in every case, showing that cytotoxicity was T cell mediated.(ABSTRACT TRUNCATED AT 250 WORDS)

In a prospective study, 17 early baseline computed tomography (CT) scans were obtained 2 or 3 days after simultaneous kidney-pancreas transplantation. Morphological changes and their relevance to the early detection of graft rejection and complications were evaluated. The pancreatic grafts were enlarged and showed signs of mild pancreatitis. Serial scans obtained during the first renal graft rejection episode were compared with the baseline CT scans (n = 7). They showed a significant increase in pancreatic graft size in the case of biopsy-proven severe renal graft rejection (P = 0.008). Normally functioning pancreatic allografts showed a 15%-40% decrease in size 1-6 months after transplantation. We conclude that the morphological changes observed early after transplantation are compatible with mild pancreatitis, which may contribute to the development of pancreatic graft thrombosis. There is an increase in the number of morphological changes during severe rejection, yet enlarged pancreatic grafts appear to recover from transplantation-related damage and regain their normal size without signs of atrophy.

Sixty-two biopsies taken from 38 kidney grafts were studied for 15 histological and 10 immunohistological parameters. The biopsies were divided into three groups, according to the clinical diagnosis at the time they were performed: group 1, rejection (n = 43); group 2, other causes of dysfunction (n = 10); and group 3, stable function (n = 9). Histological signs of acute rejection included diffuse interstitial infiltrate, tubular basement membrane damage, mononuclear leukocyte infiltration, and congestion of the peritubular capillaries. Immunoperoxidase staining with monoclonal antibodies to ten markers showed a statistically significant association between detection of T-cell receptor subunits alpha-beta (TcR2) and gamma-delta (TcR1) on infiltrating lymphocytes and of intercellular adhesion molecule-1 (ICAM-1) in tubular cells and acute rejection. These results suggest that T-cell receptors and ICAM-1 may be useful markers to differentiate acute rejection from renal graft dysfunctions due to other abnormalities.

We obtained both graft-infiltrating cells of host origin and proximal tubular epithelial cells (PTEC) of donor origin (using a selective serum-free medium) simultaneously from biopsies of rejecting renal allografts. The identity of PTEC cultures was established with monoclonal antibodies. Major histocompatibility complex class I expression could be upregulated and major histocompatibility complex class II expression induced on PTEC by 24- to 48-hr incubation with 200 U interferon-gamma. Graft-infiltrating cells were shown to lyse PTEC grown from the corresponding biopsy and not PTEC from biopsies from other patients. Therefore the lytic activity appeared to be donor-specific. Preincubation of PTEC with interferon-gamma did not consistently increase PTEC lysis. Lysis by graft-infiltrating cells obtained from four patients could be blocked by target-preincubation with anti-class I monoclonal antibodies, in one case both anti-class I and anti-class II monoclonal antibodies could block PTEC lysis. Blocking could also be obtained with anti-CD3 monoclonal antibody. PTEC lysis occurred only with graft-infiltrating cells cultured from biopsies with cellular interstitial rejection. So, PTEC seem to be a target in renal allograft rejection both in vivo and in vitro. This model system may be useful for further studies of cellular interactions between graft-infiltrating cells and their targets.

In 20 patients with a cadaveric renal allograft, serial measurements were made of the serum complement factors C3, C4, factor B (FB), and C3d, the stable conversion product of C3. Measurements were started immediately before transplantation and continued thereafter once a week to investigate whether these assays help to differentiate between acute allograft rejection (R) and an active cytomegalovirus (CMV) infection. Fifteen patients had one or more R episodes, and 9 patients suffered from an active CMV infection. Six patients had an R episode and subsequently a CMV infection 13-64 days after R. No significant changes were found in the levels of C3, C4, and FB during R or CMV infection. C3d levels remained unchanged or decreased slightly during R. However, there was a 43-500% increase in the C3d level during CMV infection. This difference in the behavior of levels of C3d during R and CMV infection is significant (P less than 0.01), and suggests that serial measurements of C3d may be useful in differentiating CMV infection from R after renal transplantation.

In the present study methods are described to obtain both graft infiltrating cells (GIC) of host origin and proximal tubular epithelial cells (PTEC) of donor origin simultaneously from biopsy material of renal allografts undergoing rejection. The identity of PTEC cultures was established using monoclonal antibodies. GIC were shown to exhibit T cell functional activity. These GIC were shown to lyse trypsinized PTEC as well as PTEC monolayers grown from the corresponding biopsy, and not PTEC isolated from biopsies obtained from other patients. Therefore the lytic activity appeared to be donor-specific. Major histocompatibility complex class I antigens were involved since donor PHA-blasts, a target population well known to express class I molecules, were lysed by GIC, and the anti-class I MoAb W6/32 blocked cytolytic activity of GIC against donor PHA-blasts and against donor PTEC. We thus established that donor-specific lysis of a defined population of kidney epithelial cells, namely PTEC, may occur. This model system, in which GIC and PTEC can be propagated from one biopsy specimen may be useful for further study of cell-cell interactions involved in allograft rejection.

Objective: Pleiotropic effects of HMG-CoA-reductase inhibitors (statins), e.g. anti-inflammatory and immunmodulatory effects, are well recognized. Recent studies have shown that statins decrease I/R-injury in rats. The aim of the present study was to evaluate the effect of atorvastatin pre-treatment on cold preservation injury in isogeneic renal transplantation and on acute renal allograft rejection in rats. Methods: Donor rats were pre-treated with atorvastatin (ATOR: 50 mg/kg/d, n = 7) or vehicle (VEH, n = 7) daily by oral gavage 2 days prior to and on the day of explantation. After explantation one kidney was snap frozen in liquid nitrogen for determination of hemeoxygenase- 1 (HO-1) expression by light-cycler PCR and the second kidney was stored for 24 h at +4° in UW solution. For investigation of cold preservation injury kidneys of male Lewis donors were then transplanted syngeneic in bilaterally nephrectomized rats and serum creatinine was measured on days 0, 1, 3 and 5 after transplantation. In the model of acute renal allograft rejection kidneys of male Fisher rats were transplanted allogeneic in uninephrectomized Lewis rats, isogeneic vehicle treated Lewis-Lewis served as control. After 5 days all grafts were harvested for determination of monocyte infiltration and MHC II expression. Results: Pre-treatment with atorvastatin improved renal function, as measured by lower serum creatinine on days 1 and 3 after transplantation (day 1: ATOR 2.04 mg/dl vs VEH 3.10 mg/dl, p < 0.0001; day 3: ATOR 1.26 mg/dl vs VEH 3.47 mg/dl, p = 0.009; t-test) and markedly reduced monocyte infiltration (ATOR 9.48 ± 1.36 vs VEH 19.77± 1.36 pos. cells/high power field, p < 0.0001) after 24 h of cold preservation and isogeneic transplantation. Pre-treatment with atorvastatin significantly reduced monocyte infiltration (VEH 41.29 ± 3.45 vs ATOR 27.60 ± 1.88 pos. cells/high power field, p = 0.0018, ANOVA; isogeneic controls 8.97 ± 1.81 pos. cells/high power field) and MHC II positive cells (VEH 20.46 ± 1.24 vs ATOR 14.75± 1.55 pos. cells/high power field, p = 0.003, ANOVA; isogeneic controls 5.4 ± 0.76 pos. cells/high power field) 5 days after allogeneic transplantation. In donor kidneys pre-treated for 2 days with atorvastatin, a significant up-regulation of the protective enzyme HO-1 was observed compared to animals pre-treated with vehicle. Conclusions: Our data demonstrate, that donor pre-treatment with atorvastatin improves renal function and decreases renal inflammation after prolonged cold storage and isogeneic renal transplantation in rats. Additionally renal inflammation was decreased 5 days after allogeneic renal transplantation in rats. The positive effect may be related to the up-regulation of the protective enzyme HO-1 in kidney tissue by atorvastatin. This observation is of high clinical significance, since it could offer a new strategy to prevent transplantationassociated injury. [ABSTRACT FROM AUTHOR]