The impact of an acute rejection episode on long-term renal allograft survival (t1/2)

Implications of Immunohistochemical Detection of C4d along Peritubular Capillaries in Late Acute Renal Allograft Rejection

BACKGROUND

Immunohistochemical detection of the C4d complement product along peritubular capillaries (PC) may indicate humoral rejection of renal allografts. We examined the frequency of PC C4d expression in renal-allograft biopsies with acute rejection (AR) arising more than 6 months after transplantation and the impact of this finding.

METHODS

C4d was detected by immunoperoxidase in 2-micron paraffin sections of consecutive biopsies obtained over a 3-year period. The extent was classified as diffuse (> or =50% PC C4d+), focal (<50% C4d+), and negative (C4d-). Clinical data were obtained by retrospective chart review. Fifty-five AR episodes with Banff 97 types 1A (n = 13), 1B (n = 26), 2A (n = 11), 2B (n = 3), and 3 (n = 2) met inclusion criteria.

RESULTS

PC C4d expression was diffuse in 23 (42%), focal in 9 (16%), and negative in 23 (42%) biopsies. AR episodes with focal and diffuse C4d expression had higher proportionate elevation of serum creatinine at biopsy and 4 weeks after diagnosis (P< or =0.05). Biopsies with diffuse PC C4d had interstitial hemorrhage (56.5%) and plasmacytic infiltrates (52%) more frequently than C4d- biopsies (22% and 16%), P = 0.02, but had no other distinctive histologic features. Graft loss was greater in diffuse (65%) compared with focal C4d+ (33%) and C4d- (33%) groups 1 year after diagnosis, P = 0.03. Other clinical and pathologic parameters did not differ significantly, including treatment received for AR.

CONCLUSION

Evidence of acute cellular with occult humoral rejection is identified in more than 40% of late AR episodes. Late acute humoral rejection may be associated with interstitial hemorrhage and plasma cells and contributes significantly to graft loss.

Conversion from cyclosporine to tacrolimus after renal transplantation improves cardiovascular risk factors

BACKGROUND

It is vital that after, renal transplantation, immunosuppression is efficacious and causes few complications. It is especially important that hyperlipidaemia, hypertension and toxic influences should be avoided because these conditions can reduce patient and transplant survival. Many studies have demonstrated beneficial effects of tacrolimus in comparison with cyclosporine with regard to these conditions. These results have suggested that a conversion to tacrolimus from cyclosporine is advantageous. Our study investigated whether patients with deteriorating renal functions can profit from this conversion.

METHODS

Thirty patients with a renal transplant were studied retrospectively, using data recorded from 3 years before to 3 years after conversion from cyclosporine to tacrolimus.

RESULTS

While renal function (glomerular filtration rate [GFR]) deteriorated progressively under cyclosporine, it stabilised and even improved under tacrolimus (creatinine: Delta(Cyc)=+1.4 mg/d; Delta(Tac=)-0.7 mg/dl; GFR: Delta(Cyc)=-35 ml/min; Delta(Tac)=14 ml/min). In addition, uric acid level (7.0 vs. 6.4 mg/dl, p<0.05) and cholesterol level (258 vs. 225 mg/dl, p<0.05) were both significantly lower under tacrolimus.

CONCLUSION

Conversion from cyclosporine to tacrolimus is recommended for patients with a kidney transplant, in which there has been a progressive fall in renal function. It leads to stabilisation or even improvement of transplant function and a reduction in cardiovascular risk factors.

Lessons from cyclosporine monotherapy in renal transplantation: the impact of acute rejection on long-term allograft outcome

The introduction of cyclosporine in kidney transplantation rapidly improved short and medium term graft and patient survival rates. Initially many trials used cyclosporine monotherapy to avoid steroid toxicity, but high acute rejection rates lead to a change in the immunosuppressant scheme. The use of prophylactic steroids significantly decreased acute rejection rates, but the long-term benefit of such a reduction has not been assessed.

METHODS

Retrospective analysis of the impact of early acute rejection on long-term outcome (10 years) in 264 consecutive renal transplants performed in a single institution between 1986 and 1993 using cyclosporine monotherapy (CM) (n=139) versus cyclosporine and prednisone (CS) (n=125). Different protocols were used for elderly or immunological high-risk patients and for transplants with delayed graft function and therefore these patients are not included. The incidence and severity of acute rejection episodes and long-term patient and graft survivals were analyzed.

RESULTS

At 1 year, acute rejection episodes showed significantly higher frequency in the CM group than in the CS group (72.66% vs 46.40%). Nevertheless, graft and patient survival rates were similar at 1, 5, and 10 years (Graft: 96.38%, 78.77%, and 59.84% vs 92.59%, 75.62%, and 53.44%;

PATIENT

99.27%, 95.06%, and 84.76% and 95.9%, 93.09%, and 88.28%).

CONCLUSION

The addition of prophylactic steroids decreases the incidence of acute rejection but does not improve the long-term graft survival. These findings suggest that in an era of new immunosuppressants, fewer acute rejection episodes will be evident requiring more effort to detect and treat subclinical rejections.

Evolution of immunosuppression at the University of Minnesota

Immunosuppressive protocols at the University of Minnesota have evolved from identical immunosuppression for all recipients (prednisone, azathioprine, and antilymphocyte globulin) to differing protocols for living (triple therapy) and cadaver (sequential therapy) donor recipients, and then to our current protocol in which all recipients receive induction therapy with rapid discontinuation of prednisone. At the same time, progress has been made in the prevention and treatment of cytomegalovirus infection along with numerous parallel improvements in patient care, including in anesthesia, dialysis, and intensive care unit care. The net result has been an incremental improvement in recipient and graft survival.

Experience with cyclosporine in pediatric renal transplantation

Three decades ago renal transplantation had become the accepted therapy for end-stage renal disease in children. Cyclosporine (CsA) was introduced into the majority of clinical immunosuppressive protocols in the 1980s and attained a vital place in the armamentarium of antirejection drugs for children. However, CsA therapy is not without adverse effects, notably posttransplant hypertension, hyperlipidemia, and nephrotoxicity. The cosmetic side effects of CsA, principally hirsutism and gum hyperplasia, are significant and very important to children particularly when drug compliance issues are vital to achieve success. The central role CsA has played to date in the development of successful treatment protocols for children undergoing renal transplantation is explored, including the importance of therapeutic drug level monitoring to optimize clinical outcomes.

Steroid Withdrawal in Renal Transplant Patients on Triple Therapy with a Calcineurin Inhibitor and Mycophenolate Mofetil: A Meta-analysis of Randomized, Controlled Trials

BACKGROUND

Two previous meta-analyses of randomized, controlled trials of steroid withdrawal after renal transplantation have shown significant increases in acute rejection (both analyses) and graft failure rates (the last analysis). A new examination of this topic including only randomized, controlled trials based on currently used, new, potent therapy with calcineurin inhibitors and mycophenolate mofetil (MMF), avoiding early trials with azathioprine, is justified.

METHODS

Steroid withdrawal in patients on triple therapy including a calcineurin inhibitor and MMF was assessed through meta-analysis of randomized, controlled trials in which intention-to-treat rates of acute rejection and renal allograft failure were established after steroid withdrawal or continuation.

RESULTS

Six trials were included, four in patients receiving cyclosporine and two in patients receiving tacrolimus. The risk ratio (RR) for acute rejection was 2.28 (95% confidence interval [CI], 1.65-3.16; P < 0.00001) and the pooled risk difference (RD) was 0.08 (95% CI, 0.05-0.11; P < 0.001), indicating that the proportion of patients with acute rejection after prednisone withdrawal was significantly higher compared with controls. The RR for graft failure was 0.73 (95% CI, 0.42-1.28; P = 0.27) and the RD was -0.01 (95% CI, -0.03-0.01; P = 0.28), indicating that the proportion of patients with graft failure after withdrawal was not significantly different from that observed in controls. Total cholesterol was significantly lower after steroid withdrawal (weighted mean difference, -0.53 microM (95% CI, -0.70 to -0.36; P < 0.0001).

CONCLUSIONS

Renal allograft recipients on triple therapy with a calcineurin inhibitor, MMF, and steroids are at low but significant risk of acute rejection after steroid withdrawal but do not suffer an increased risk of early graft failure. It is necessary to extend controlled follow-up to confirm graft function stabilization.

Use of simulect can reduce the incidence of acute rejection and demonstrates with superior 3-year patient and graft survival rates in renal transplantation

BACKGROUND

Acute rejection is a major cause of graft loss in renal transplantation. Because the highest risk for acute rejection is in the first month posttransplantation, improved prophylaxis could be most beneficial in this period. Simulect administration provides 30 to 45 days of immunoprophylaxis against acute rejection during the critical period after transplantation.

OBJECTIVES

We sought to assess the incidence of acute rejection episodes and the safety and tolerability of Simulect plus Neoral immunosuppression. Patient and graft survival rates up to 3 years posttransplantation were evaluated.

METHOD

Forty-one transplant recipients received Simulect by intravenous infusion of an initial 20-mg dose on the day of renal transplantation and a second 20-mg dose on day 4 posttransplant. All renal recipients received immunosuppression with Neoral and steroid.

RESULTS

There were eight cases (19.5%) of acute rejection within 1 year. The rejection episodes were easily reversed with steroid pulse therapy in seven patients except for graft loss. The 1-, 2-, and 3-year graft survival rates were 95%, 93%, and 88%, respectively. Overall, the 3-year patient survival rate was 100%.

CONCLUSIONS

Simulect in combination with Neoral and steroid-reduced the incidence of acute rejection without an increase in adverse events. The low incidence and severity of acute rejection may have led to the superior 3-year patient and graft survival rates in renal transplantation.

Differentiation between chronic rejection and chronic cyclosporine toxicity by analysis of renal cortical mRNA

BACKGROUND

In kidney transplantation, chronic allograft nephropathy (CAN) is the major cause of graft loss. Causes of CAN include chronic rejection and chronic cyclosporine A (CsA) nephrotoxicity. It is necessary to differentiate between these two entities in order to apply the appropriate therapeutic regimen for the individual patient, but this is hampered by the lack of discriminating functional and morphologic parameters. We investigated whether renal cortical mRNA levels for several matrix proteins can serve as discriminating parameters.

METHODS

Patients with chronic rejection (N= 19) and chronic CsA toxicity (N= 17) were selected by clinical and histologic criteria. Protocol biopsies without histologic abnormalities, taken at 6 months after transplantation from patients receiving CsA, were used as controls (N= 6). Total RNA was extracted from the renal biopsy tissue, and mRNA levels of transforming growth factor-beta (TGF-beta) and the extracellular matrix (ECM) molecules collagen Ialpha1, IIIalpha1, IValpha3, decorin, fibronectin, and laminin beta2 were measured by real-time polymerase chain reaction (PCR).

RESULTS

In both patient groups, the mean collagen IValpha3 and fibronectin mRNA levels were significantly elevated compared to those in controls, whereas only in CsA toxicity were the laminin beta2 and TGF-beta mRNA levels significantly increased. The increase of laminin beta2 and TGF-beta mRNA levels was significantly higher in the CsA toxicity group than in the chronic rejection group (P < 0.001 and P= 0.004, respectively). Receiver-operating characteristic (ROC) curve analysis showed that with a 15.6-fold increase in laminin beta2 mRNA expression as cut-off point, the presence of CsA toxicity could be predicted with an 87% sensitivity and an 88% specificity.

CONCLUSION

Renal laminin beta2 and TGF-beta mRNA levels can be used to differentiate between chronic rejection and chronic CsA toxicity in renal transplants. The method of mRNA quantification might be applicable as an additional diagnostic tool in clinical practice.

Long-term effects of acute ischemia and reperfusion injury

Ischemia reperfusion (I/R) injury plays a major role in delayed graft function and long-term changes after kidney transplantation. By using different therapeutic strategies to prevent I/R injury in rat models of kidney transplantation we studied relationships between inflammatory cell arrival and adhesion molecule expression. In other rat models for acute renal failure we investigated the effect of up-regulation of protective genes such as heme oxygenase-1 (HO-1) on infiltrating cells, showing that infiltrating cells also contribute to beneficial effects. In order to gain more insight into the complex mechanisms of long-term changes after kidney transplantation, we started a protocol biopsy program to study histologic changes 6, 12, and 26 weeks after transplantation. The following article clarifies some of the complex mechanisms contributing to long-term changes caused by I/R injury.

Early T cell response to allografts occurring prior to alloantigen priming up-regulates innate-mediated inflammation and graft necrosis

The early inflammatory response within organ allografts is initiated by ischemia/reperfusion (I/R) and promotes subsequent alloantigen-primed T cell recruitment into and rejection of the graft. Polymorphonuclear leukocyte (PMN)-mediated tissue damage is a primary component of the early inflammation in allograft rejection. We sought to compare and elucidate the mechanism of early PMN infiltration into cardiac isografts and allografts. Despite identical production of PMN attractant chemokines, PMN infiltration following reperfusion into syngeneic and allogeneic grafts was not equivalent. PMN infiltration into isografts peaked at 9 to 12 hours post-transplant and quickly resolved. In contrast, PMN infiltration into allografts continued to elevated levels, peaking at 24 hours post-reperfusion. This amplified PMN infiltration into allografts did not resolve until 72 hours post-reperfusion and was accompanied by marked parenchymal necrosis. This early innate inflammatory response was regulated by IFN-gamma-producing CD8+ T cells present in the recipient before detectable alloantigen T cell priming. Co-culture with CD62L(low) CD8+ T cells, but not CD62L(high) CD8+ or CD62L(low) CD4+ T cells, harvested from naïve animals induced allogeneic endothelial cells to express IFN-gamma-dependent chemokines. These data demonstrate CD8+ T cell-mediated attack on the vascular endothelium of allografts within hours following organ reperfusion that amplifies innate immune-mediated intra-graft inflammation and necrosis.

The role of anti-IL-2 receptor in high-risk kidney transplant patients

Anti-IL-2 receptor has been proved to be effective in reducing the rate of acute rejection in kidney transplantation and also improving both the rate of graft and patient survival. In this study, we retrospectively review the role of anti-IL-2 receptor as induction immunosuppression in immunologically high-risk kidney transplant patient compared with normally low-risk patients.

METHODS

From January 1999 to December 2002, we performed 246 kidney transplantations in two transplant centers in Bangkok. These were divided into two groups: group 1, high-risk group containing 50 patients who had one of the following criteria: (1) high panel reactive antibody (>50%); (2) retransplantation; (3) marginal donor (with expectancy of delayed graft function); (4) spouse donor; (5) >4 HLA mismatch. All group 1 patients receive anti-IL-2 receptor as induction immunosuppression (either Basiliximab (n = 27) or Daclizumab (n = 23).) Group 2 consisted of the control group of 196 patients with normal immunological risk. The following data of both groups were collected and analyzed: patient demography, type of donor, acute rejection incidence, severity, and time.

RESULTS

In this study, the anti-IL-2 receptors are 27 cases of Basiliximab and 23 cases of Daclizumab. The rates of acute rejection are not significantly different in both groups, namely, 46 of 194 (23.7%) in group 2 compared with 10 of 50 (20%) episodes in group 1 (P = .602). All rejections in both groups responded to pulse steroid treatment. The mortality rate and rate of graft failure were also not significantly different, i.e., 6 of 196 (3.1%) vs 2 of 50 (4.0%) (P = .666) and 7 of 196 (3.6%) vs 3 of 50 (6.0%) (P = .429) in low risk group versus high risk group, respectively. Kaplan-Meier estimates of the probabilities of acute rejection free, patient survival rate, and graft survival rate also showed no difference between groups.

CONCLUSIONS

The use of anti-IL-2 receptor antibodies as induction immunosuppression in immunologically high-risk patients results in the same rate of acute rejection, severity of acute rejection, graft survival, and patient survival as recipients with normal immunological risk.

C4d Deposition in Early Renal Allograft Protocol Biopsies

BACKGROUND

Deposition of the complement protein C4d in renal allograft biopsies obtained during graft dysfunction and rejection has been proposed to be a sensitive marker of antibody-mediated acute rejection. To determine the diagnostic specificity of C4d deposition, it is important to study biopsies from allografts with no evidence of dysfunction. In this study, we examined C4d deposition in protocol biopsies obtained irrespective of clinical status.

METHODS

Immunohistochemistry for C4d was performed on routine protocol biopsies preimplantation and on day 7 posttransplantation from 48 unselected renal allografts. Serum samples obtained up to 1 month after transplantation were assayed for donor-reactive antibodies (DRA). Results were correlated with histopathology and clinical outcome measures.

RESULTS

Diffuse C4d deposition was detected in the peritubular capillaries of 6 of 48 (13%) biopsies. C4d deposition was present in 5 of 15 (33%) biopsies that showed acute rejection (Banff 97, category 4) but only in 1 of 33 (3%) biopsies with no rejection (P=0.003, 97% specificity). Posttransplant DRAs were detected in 21 of 48 (44%) patients. All five recipients with C4d deposition and rejection had posttransplant DRA; the recipient whose biopsy showed C4d positivity, but not rejection, did not have detectable DRA. C4d deposition was not treated with plasmapheresis or intravenous immunoglobulin and was not associated with poor posttransplant graft outcome at 1-year follow-up.

CONCLUSIONS

Our results show that in early posttransplant protocol biopsies, C4d is a specific marker for the presence of humoral rejection, as indicated by its association with DRA and acute histologic rejection.

Role of integrin CD103 in promoting destruction of renal allografts by CD8 T cells

Infiltration of CD8(+)TCRalphabeta(+) T-effector populations (CD8 effectors) into graft epithelial compartments has long been recognized as a key lesion in progression of clinical renal allograft rejection. While the afferent phase of allograft immunity is increasingly well-defined, the efferent pathways by which donor-reactive CD8-effector populations access and ultimately destroy the graft renal tubules (rejection per se) have received remarkably little attention. This is an important gap in our knowledge of transplantation immunology, because epithelial compartments comprise the functional elements of most commonly transplanted organs including not only kidney, but also liver, lung, pancreas, and intestine. Furthermore, there is increasing evidence that attack of graft epithelial elements by CD8-effector populations not only causes short-term graft dysfunction but is also a major contributor to development of chronic allograft nephropathy and late graft loss, which now represent the salient clinical problems. Recent studies of the T-cell integrin, alpha(E)beta(7) (CD103), have provided insight into the mechanisms that promote interaction of CD8 effectors with graft epithelial compartments. The purpose of this communication is to review the known properties of the CD103 molecule and its postulated role in the efferent phase of renal allograft rejection.

Efficacy and safety of tacrolimus compared with cyclosporine microemulsion in primary simultaneous pancreas-kidney transplantation: 1-year results of a large multicenter trial

BACKGROUND

Simultaneous pancreas-kidney transplantation (SPK) transplantation has become an accepted therapy for type 1 diabetic patients with end-stage renal disease. This open-label, multicenter study compared the efficacy and safety of tacrolimus with the microemulsion (ME) formulation of cyclosporine in a clinical setting. The 1-year results are reported here.

METHODS

The study was conducted in 10 European centers and one center in Israel. One hundred three patients were randomly assigned to tacrolimus and 102 to cyclosporine-ME. All patients received concomitant rabbit anti-T-cell globulin induction therapy, mycophenolate mofetil (MMF), and short-term cortico-steroids. The initial daily oral doses were 0.2 mg/kg for tacrolimus, 7 mg/kg for cyclosporine-ME, and 2 to 3 g for MMF.

RESULTS

The 1-year incidence of biopsy-proven kidney or pancreas acute rejection was lower with tacrolimus (27.2%) than with cyclosporine-ME (38.2%; P = 0.09). Pancreas graft survival at 1 year was 91.3% with tacrolimus and 74.5% with cyclosporine-ME (P <0.0005). Renal graft survival was similar in the two study groups. There were no significant treatment-related differences in pancreatic or renal graft function. In total, 34 patients switched treatment from cyclosporine-ME to tacrolimus, but only 6 patients receiving tacrolimus required alternative therapy. Mean doses of MMF at 1 year were also lower in the tacrolimus group (1.36 vs. 1.67 g/day; P = 0.007).

CONCLUSION

These findings support the use of tacrolimus therapy for uremic patients with type 1 diabetes who are undergoing SPK transplantation.

A DECADE OF PROGRESS IN KIDNEY TRANSPLANTATION

Kidney transplantation has become the treatment of choice for patients with end-stage renal disease because of better surgical techniques and the availability of more powerful immunosuppressive drugs. Regimens of immunosuppression should combine both short-term outcomes and predictors of long-term safety and survival. The value of tacrolimus for immunosuppression protocols lies in its ability to reduce the immunologic risk to the allograft and its excellent safety profile. Outcomes for kidney-transplant recipients can be further optimized by individualizing therapy to address each patient's risk profile.

Frequency and impact of nonadherence to immunosuppressants after renal transplantation: a systematic review

Nonadherence to immunosuppressants is recognized to occur after renal transplantation, but the size of its impact on transplant survival is not known. A systematic literature search identified 325 studies (in 324 articles) published from 1980 to 2001 reporting the frequency and impact of nonadherence in adult renal transplant recipients. Thirty-six studies meeting the inclusion criteria for further review were grouped into cross-sectional and cohort studies and case series. Meta-analysis was used to estimate the size of the impact of nonadherence on graft failure. Only two studies measured adherence using electronic monitoring, which is currently thought to be the most accurate measure. Cross-sectional studies (n=15) tended to rely on self-report questionnaires, but these were poorly described; a median (interquartile range) of 22% (18%-26%) of recipients were nonadherent. Cohort studies (n=10) indicated that nonadherence contributes substantially to graft loss; a median (interquartile range) of 36% (14%-65%) of graft losses were associated with prior nonadherence. Meta-analysis of these studies showed that the odds of graft failure increased sevenfold (95% confidence interval, 4%-12%) in nonadherent subjects compared with adherent subjects. Standardized methods of assessing adherence in clinical populations need to be developed, and future studies should attempt to identify the level of adherence that increases the risk of graft failure. However, this review shows nonadherence to be common and to have a large impact on transplant survival. Therefore, significant improvements in graft survival could be expected from effective interventions to improve adherence.

Anti-interleukin-2 receptor antibodies for the prevention of rejection in pediatric renal transplant patients: current status

The anti-interleukin-2 receptor (anti-IL-2R) antibody therapy is an exciting approach to the prevention of acute rejection after renal allograft transplantation whereby immunosuppression is exerted by a selective and competitive inhibition of IL-2-induced T cell proliferation, a critical pathway of allorecognition. The anti-IL-2R antibodies specifically block the alpha-subunit of the IL-2R on activated T cells, and prevent T cell proliferation and activation of the effector arms of the immune system. The anti-IL-2R antibodies are used as induction therapy, immediately after renal transplantation, for prevention of acute cellular rejection in children and adults. During acute rejection, the IL-2Ralpha chain is no longer expressed on T cells; thus, the antibodies cannot be used to treat an existing acute rejection. Two anti-IL-2R monoclonal antibodies are currently in clinical use: daclizumab and basiliximab. In placebo-controlled phase III clinical trials in adults, daclizumab and basiliximab in combination with calcineurin inhibitor-based immunosuppression, significantly reduced the incidence of acute rejection and corticosteroid-resistant acute rejection without increasing the risk of infectious or malignant complications, and neither antibody was associated with the cytokine-release syndrome. Children who receive calcineurin inhibitors and corticosteroids for maintenance immunosuppression, as well as children who receive augmented immunosuppression to treat acute rejection, are at increased risk of growth impairment, hypertension, hyperlipidemia, lymphoproliferative disorders, diabetes mellitus, and cosmetic changes. In older children, the cosmetic adverse effects frequently reduce compliance with the treatment, and subsequently increase the risk of allograft loss. Being effective and well tolerated in children, the anti-IL-2R antibodies reduce the need for calcineurin inhibitors while maintaining the overall efficacy of the regimen; thus, the anti-IL-2R antibodies increase the safety margin (less toxicity, fewer adverse effects) of the baseline immunosuppression. Secondly, the anti-IL-2R antibodies decrease the need for corticosteroids and muromonab CD3 (OKT3) in children as a result of decreased incidence of acute rejection. The recommended pediatric dose of daclizumab is 1 mg/kg intravenously every 14 days for five doses, with the first dose administered within 24 hours pre-transplantation. This administration regimen maintains daclizumab levels necessary to completely saturate the IL-2Ralpha (5-10 microg/mL) in children for at least 12 weeks.The recommended pediatric dose of basiliximab for recipients <35 kg is 10 mg, and 20 mg for recipients > or =35 kg, intravenously on days 0 and 4 post-transplantation. This administration regimen maintains basiliximab levels necessary to completely saturate the IL-2Ralpha (>0.2 microg/mL) in children for at least 3 weeks.

Mycophenolate mofetil in solid-organ transplantation

This review focuses on the use of mycophenolate mofetil (MMF) as an immunosuppressive agent in solid-organ transplantation. MMF, a non-competitive inhibitor of inosine monophosphate dehydrogenase, blocks de novo purine synthesis in T and B lymphocytes, resulting in the selective inhibition of proliferation of these cells in response to antigenic stimuli. MMF may also promote apoptosis of these cells. The immunosuppressive ability of MMF is thought to derive mainly from the inhibition of inosine monophosphate dehydrogenase. The other effects of MMF include suppression of antibody synthesis by B lymphocytes, inhibition of proliferation of smooth muscle cells in culture and impaired glycosylation of adhesion molecules. MMF may exhibit anti-inflammatory effects resulting from decreased activity of the inducible form of nitric oxide synthase, a consequence of depletion of tetrahydrobiopterin, which leads to decreased generation of peroxynitrite, a pro-inflammatory molecule. The pharmacokinetics, pharmacodynamics and principles underlying therapeutic drug monitoring of MMF are reviewed. The results of the pivotal clinical trials of MMF in kidney and heart transplantation are discussed and a summary of the major studies demonstrating a positive effect of MMF on renal transplantation outcomes is presented. The use of MMF in the context of ABO-incompatible renal transplantation, renal transplantation in highly sensitised and cross-match positive recipients, humoral rejection of renal allografts, chronic allograft nephropathy and steroid/calcineurin inhibitor minimisation in renal transplantation are also discussed.

Histological evaluation of renal allograft protocol biopsies in the early period and 1 year after transplantation

We histologically evaluated protocol biopsy specimens of renal allografts obtained in the early period and 1 year after transplantation. The patients were divided into those with at least one history of acute rejection (AR group) and no history of rejection (NAR group), and the histopathological features in the two groups were compared. A total of 45 early protocol biopsy specimens were obtained from 40 patients, and 31 1-year biopsy specimens were obtained from 30 patients. Acute rejection (AR) or borderline change was observed in the early protocol biopsy specimens from 19 (45.2%) cases. AR or borderline change was observed in 12 of 19 (63.2%) in the AR group, and in 7/26 cases (26.9%) in the NAR group. The incidence of AR or borderline change in the AR group was higher than in the NAR group. Toxic tubulopathy was found in the early protocol biopsy in 16 cases (35.6%). The 1-year biopsies tended to reveal more complicated findings. Chronic rejection (CR) was seen in 8/16 cases (50.0%) in the AR group, and it was more frequent than NAR group (two cases, 13.3%). In conclusion, the incidences of both AR and CR were higher in the cases with a previous episode of AR. The early protocol biopsy was useful in screening for subclinical AR and toxic tubulopathy. The 1-year biopsy was useful for evaluating various types of chronic graft damage. We expect that adequate treatment based on protocol biopsy findings in each patient will lead to better graft survival.

Mycophenolate mofetil reduces deterioration of renal function in patients with chronic allograft nephropathy

BACKGROUND

Although studies have shown that mycophenolate mofetil (MMF) with cyclosporine (CsA) and prednisone can reduce the incidence of acute rejection and increase the half-life of the graft, the effects of MMF on established chronic allograft nephropathy (CAN) are controversial.

METHODS

We studied 121 patients with biopsy-proven CAN, 59 treated with CsA and prednisone and 62 treated with triple-drug therapy with azathioprine. At inclusion, each group received 2 g per day of MMF and azathioprine was stopped. Renal function was measured by the glomerular filtration rate (GFR) obtained by creatinine clearance (Cockcroft-Gault) and monitored by the slope of the GFR, adjusted using linear regression.

RESULTS

The median follow-up, after incorporation of MMF, was 36 (13-36) months, with 103 (85.1%) having a full 3-year follow-up. Before the introduction of MMF, there was progressive deterioration in renal function (GFR: 54.8+/-20.9 vs. 39.7+/-14.0 mL/min, P<0.001). After introduction of MMF, renal function remained stable (GFR: 39.7+/-14.0 vs. 41.3+/-10.8 mL/min, P=NS), with a significant change in the slope of the GFR (-0.0144 vs. +0.00045, P<0.001). In 65 patients in whom CsA blood levels remained unchanged during follow-up (148.0+/-65.6 vs. 154.1+/-58.2, P=NS), the slope of the GFR showed a reduction in loss of renal function (-0.0147 vs. -0.0001, P<0.001).

CONCLUSIONS

Treatment with MMF reduced the progressive deterioration of renal function in patients with CAN, independently of the blood levels of CsA.

Three-year posttransplant graft survival in renal-transplant patients with graft function at 6 months receiving tacrolimus or cyclosporine microemulsion within a triple-drug regimen

BACKGROUND

Registry data can provide valuable information about possible treatment effects; however, pretreatment differences in patient characteristics may influence treatment assignment. Careful analysis must therefore be undertaken when evaluating treatment differences in the context of nonrandomized studies so that the impact of treatment selection bias is minimized.

METHODS

A multivariable risk factor analysis of adult patients registered in the US Renal Data System who received a primary renal allograft during 1995 to 1998 was undertaken to compare 3-year graft survival using tacrolimus or Neoral with mycophenolate mofetil (MMF) and steroids.

RESULTS

In total, 9,449 patients were included (cadaveric donor n=6,011; living donor n=3,438). Patients (2,130) received tacrolimus, and 7,319 received Neoral. At 3 years posttransplant, the proportion of cadaveric donor recipients experiencing all causes of graft loss was 10.0% for tacrolimus and 10.6% for Neoral; for living donor recipients these figures were 6.5% and 6.7%, respectively (unadjusted Kaplan-Meier analysis). The incidence of graft failure excluding death was also similar between the two groups. With Cox proportional hazards modeling, the adjusted relative hazard of 3-year graft failure for cadaveric donor patients taking tacrolimus versus Neoral was 1.02 (95% confidence interval [CI] 0.8-1.3), and for living-donor recipients it was 1.15 (95% CI 0.8-1.8).

CONCLUSIONS

These results indicate excellent 3-year graft survival for both cadaveric and living-donor renal-transplant patients receiving either Neoral or tacrolimus with MMF and steroids, with no significant differences between treatment groups. On the basis of these results, relative cost-effectiveness may become increasingly important in selection of tacrolimus or Neoral as primary immunosuppressant for renal-transplant patients.

The natural history of chronic allograft nephropathy

BACKGROUND

With improved immunosuppression and early allograft survival, chronic allograft nephropathy has become the dominant cause of kidney-transplant failure.

METHODS

We evaluated the natural history of chronic allograft nephropathy in a prospective study of 120 recipients with type 1 diabetes, all but 1 of whom had received kidney-pancreas transplants. We obtained 961 kidney-transplant-biopsy specimens taken regularly from the time of transplantation to 10 years thereafter.

RESULTS

Two distinctive phases of injury were evident as chronic allograft nephropathy evolved. An initial phase of early tubulointerstitial damage from ischemic injury (P<0.05), prior severe rejection (P<0.01), and subclinical rejection (P<0.01) predicted mild disease by one year, which was present in 94.2 percent of patients. Early subclinical rejection was common (affecting 45.7 percent of biopsy specimens at three months), and the risk was increased by the occurrence of a prior episode of severe rejection and reduced by tacrolimus and mycophenolate therapy (both P<0.05) and gradually abated after one year. Both subclinical rejection and chronic rejection were associated with increased tubulointerstitial damage (P<0.01). Beyond one year, a later phase of chronic allograft nephropathy was characterized by microvascular and glomerular injury. Chronic rejection (defined as persistent subclinical rejection for two years or longer) was uncommon (5.8 percent). Progressive high-grade arteriolar hyalinosis with luminal narrowing, increasing glomerulosclerosis, and additional tubulointerstitial damage was accompanied by the use of calcineurin inhibitors. Nephrotoxicity, implicated in late ongoing injury, was almost universal at 10 years, even in grafts with excellent early histologic findings. By 10 years, severe chronic allograft nephropathy was present in 58.4 percent of patients, with sclerosis in 37.3 percent of glomeruli. Tubulointerstitial and glomerular damage, once established, was irreversible, resulting in declining renal function and graft failure.

CONCLUSIONS

Chronic allograft nephropathy represents cumulative and incremental damage to nephrons from time-dependent immunologic and nonimmunologic causes.

Basiliximab widens the therapeutic window for AUC-monitored neoral therapy early after kidney transplantation

Early adequate cyclosporine exposure has been shown to predict low acute rejection. Recently basiliximab induction has been added to immunosuppressive regimens to further reduce rejection. The aim of this study was to determine the importance of achieving the early cyclosporine therapeutic threshold with basiliximab induction. A retrospective analysis of first cadaver and nonidentical living donor transplant recipients treated with or without basiliximab induction was performed. All patients (n = 170) received neoral, mycophenolate mofetil, and prednisone. The cyclosporine absorption profile was measured on day 3. Adequate cyclosporine exposure was defined as area under the curve (AUC) 0-4: >4400 microg x h/L at day 3. The primary outcome was acute rejection (AR) within the first 6 month. In the no basiliximab (control) group, AR occurred in 22% (17/78) of recipients and was strongly associated with low cyclosporine exposure on day 3. AR occurred in 39% (9/23) with cyclosporine AUC0-4 < 4400 microg x h/L compared with 15% (8/55) with AUC0-4 > 4400 microg x h/L (P =.016). In the basiliximab group, AR occurred in only 9% (8/92) of recipients and did not correlate with cyclosporine exposure. AR occurred in 8% (2/24) with cyclosporine AUC0-4 < 4400 microg x h/L compared with 9% (6/68) with AUC0-4 > 4400 microg x h/L (P =.94). Achieving cyclosporine therapeutic targets by day 3 may not be required when anti-IL2 induction is used.

Five-year results of kidney transplantation under tacrolimus-based regimes: the persisting significance of vascular rejection

BACKGROUND

Acute rejection has been the major risk factor for medium-term kidney graft loss because of chronic allograft nephropathy. We investigated whether the use of improved immunosuppression has altered the relationship between acute and chronic rejection by analyzing data from 245 renal transplant patients receiving Tacrolimus-based immunosuppression.

RESULTS

Five-year graft survival (censored for death with functioning graft) was 88.8% with no significant difference between living and cadaveric kidney transplants. The only significant predictor of medium-term graft loss was acute vascular rejection.

CONCLUSION

Under Tacrolimus-based immunosuppression, the occurrence of acute interstitial rejection, even when occurring late, repeatedly, or with failure of graft function to return to baseline, was not associated with chronic allograft nephropathy or medium-term graft loss. Vascular rejection remains the major immunological obstacle to long-term transplant success. Five-year overall survival rates with a functioning graft of 80% with 90% graft survival censored for death with function seem to be realistic and achievable goals.

Influence of hypercholesterolemia and acute graft rejection on chronic nephropathy development in renal transplant recipients

Graft endothelial lesions resulting from acute rejection may be sustained by concomitant hypercholesterolemia, thus increasing the risk of chronic graft failure. The present study was undertaken to examine the influence of hypercholesterolemia and acute graft rejection (AGR) episodes on graft function and graft loss due to chronic nephropathy. A cohort of 336 patients transplanted between 1993 and 2000 having graft function at 12 months after transplantation were examined. Immunosuppressive therapy consisted of CsA, azathioprine, and corticosteroids in 90% with 10% of patients receiving mycophenolate mofetil in place of azathioprine. During the first year after transplantation, AGR occurred in 134 (39.8%) and hypercholesterolemia (6.2 mmol/L) in 132 (39.2%) of patients. The population was divided into four groups according to AGR occurrence and cholesterol concentrations during the first year after transplantation for analysis of serum creatinine concentrations and graft loss at 5 years of follow-up. Patients with AGR irrespective of cholesterol levels displayed significantly higher creatinine concentrations. Graft loss in these patients increased over twofold compared to the remaining groups. Patients without hypercholesterolemia and AGR showed normal creatinine concentrations and low graft loss rates during 5 years of follow-up.

Longitudinal evaluation of the pharmacokinetics of cyclosporin microemulsion (Neoral) in pediatric renal transplant recipients and assessment of C2 level as a marker for absorption

BACKGROUND

There are important differences in CsA pharmacokinetics between adult and pediatric patients, such that pharmacokinetic data can not necessarily be extrapolated from the adult to the pediatric setting. Research in adult renal transplant patients has shown that adequate cyclosporin exposure (AUC0-4) in the first week post-transplant is important for successful clinical outcome, and that cyclosporin concentration at 2 h post-dose (C2) provides the optimal single-time point marker for AUC0-4. Clinically, dose management based on C2 level results in a low incidence of acute rejection in the adult renal transplant population. The study reported here undertook pharmacokinetic profiling in de novo renal transplant patients over a period of 6 months and retrospectively assessed alternative monitoring strategies based on pharmacokinetic findings and clinical outcomes.

METHODS

This open-label, observational, prospective study was carried out at four UK transplant centers over a period of 6 months in pediatric de novo renal transplant recipients receiving the microemulsion formulation of cyclosporin (Neoral) according to local protocol. Twelve-hour pharmacokinetic profiles (8-16 blood samples each) were performed on days 5 and 14 and at weeks 4, 13 and 26 post-transplant.

RESULTS

Thirty-two patients were recruited (median age 10 yr, range 3-18 yr). At 6 months, patient survival was 100% and graft survival was 91%. The incidence of clinically determined acute rejection was 41% (13 of 32). Six patients discontinued Neoral before 6 months: three due to graft loss, one due to rejection, one due to renal toxicity and one due to hypertrichosis. At all time points studied, C2 correlated more closely with AUC0-4 and with AUC0-12 than did the pre-dose cyclosporin concentration (C0, or trough). Patients achieving C2 > 1.5 microg/mL by the fifth postoperative day experienced no acute rejection in the first 6 months, compared with a 50% rejection rate among patients with C2 < 1.5 microg/mL (P < 0.05). Binary logistic regression analysis showed that C2 level >1.7 microg/mL was associated with approximately 90% probability of freedom from acute rejection. Analysis of renal function across patients grouped according to cyclosporine exposure (AUC0-4, C2) showed no adverse effects of higher/increased exposure on creatinine or GFR.

CONCLUSIONS

C2 level provides a more reliable marker for CsA exposure than C0 in pediatric renal transplant recipients, and is more closely predictive of acute rejection risk. A C2 target of 1.7 microg/mL appears appropriate in this population during the immediate post-transplant period in order to maximize clinical benefit.

Molecular heterogeneity in acute renal allograft rejection identified by DNA microarray profiling

BACKGROUND

The causes and clinical course of acute rejection vary, and it is not possible to predict graft outcome reliably on the basis of available clinical, pathological, and genetic markers. We hypothesized that previously unrecognized molecular heterogeneity might underlie some of the variability in the clinical course of acute renal allograft rejection and in its response to treatment.

METHODS

We used DNA microarrays in a systematic study of gene-expression patterns in biopsy samples from normal and dysfunctional renal allografts. A combination of exploratory and supervised bioinformatic methods was used to analyze these profiles.

RESULTS

We found consistent differences among the gene-expression patterns associated with acute rejection, nephrotoxic effects of drugs, chronic allograft nephropathy, and normal kidneys. The gene-expression patterns associated with acute rejection suggested at least three possible distinct subtypes of acute rejection that, although indistinguishable by light microscopy, were marked by differences in immune activation and cellular proliferation. Since the gene-expression patterns pointed to substantial variation in the composition of immune infiltrates, we used immunohistochemical staining to define these subtypes further. This analysis revealed a striking association between dense CD20+ B-cell infiltrates and both clinical glucocorticoid resistance (P=0.01) and graft loss (P<0.001).

CONCLUSIONS

Systematic analysis of gene-expression patterns provides a window on the biology and pathogenesis of renal allograft rejection. Biopsy samples from patients with acute rejection that are indistinguishable on conventional histologic analysis reveal extensive differences in gene expression, which are associated with differences in immunologic and cellular features and clinical course. The presence of dense clusters of B cells in a biopsy sample was strongly associated with severe graft rejection, suggesting a pivotal role of infiltrating B cells in acute rejection.

Chronic allograft nephropathy uniformly affects recipients of cadaveric, nonidentical living-related, and living-unrelated grafts

BACKGROUND

Chronic allograft nephropathy (CAN) remains a major barrier to long-term allograft survival. The authors retrospectively compared the development of CAN in recipients of cadaveric (CAD), living-related donor (LRD), and living-unrelated donor (LURD) transplants at their center.

METHODS

The authors retrospectively examined the impact of various factors on the incidence of CAN using univariate and multivariate proportional hazards analysis in a single-center kidney transplant population.

RESULTS

Between 1 January 1990 and 31 May 2000, 2,140 kidney-alone transplants were performed at the authors' center. The overall 5-year incidence of biopsy-proven CAN was 12.2% (n=203). Risk factors for CAN included the number of transplants (P=0.0001), acute rejection (P=0.0001), panel reactive antibody (P=0.0001), discharge creatinine (P=0.0001), 1-year creatinine (P=0.0015), delayed graft function (P=0.007), total human leukocyte antigen (HLA)-B and -DR mismatches (P=0.0005), recipient age (P=0.003), black donor race (P=0.001), black recipient race (0.0457), donor age (P=0.0053), cold storage time (P=0.019), and cytomegalovirus infections (P=0.002). Interestingly, although the LRD HLA-identical recipients had a significantly lower incidence of CAN (P=0.0015), the incidence of CAN in CAD and HLA-nonidentical LRD recipients did not differ. Graft survival was significantly worse in CAD recipients compared with all other groups (P<0.001).

CONCLUSIONS

These results demonstrate the importance of immunologic and nonimmunologic factors on the development of CAN. The disparities in overall graft survival, despite the similarities in CAN rates, suggests that other factors, in addition to CAN, influence the increase in graft loss in CAD transplant recipients.

Predicting long-term kidney graft survival: can new trials be performed?

BACKGROUND

As short-term transplant results improve, it has become difficult to use patient or graft survival or acute rejection as clinical trial endpoints, except in large, multicenter studies. Despite better outcomes, graft failure continues over time.

METHODS

We studied 6- and 12-month creatinine (Cr) level and change in creatinine (deltaCr) level (3-12 months, 6-12 months) as predictors of graft survival for 1,389 primary kidney transplants (minimum graft survival 1 year). Determining the prognostic value of Cr level (6 or 12 months), the subgroups were as follows: less than 1, 1 to 1.4, 1.5 to 1.9, 2.0 to 2.4, 2.5 to 2.9, and greater than or equal to 3 mg/dL. For deltaCr level, the subgroups were as follows: less than 0, 0, 0.01 to 0.2, and greater than 0.2. Subgroup actuarial graft survival was determined. Cox regression analyses were performed with forward, stepwise selection.

RESULTS

After 12-month Cr level entered the model, no other variable was significant. Repeating this with continuous variables, 12-month Cr level was again the best predictor. Five-year graft survival for 12-month Cr level less than 1 (n=38) was 95%; for 1.0 to 1.4 (n=454), 87%; for 1.5 to 1.9 (n=463), 86%; for 2.0 to 2.4 (n=166), 78%; for 2.5 to 2.9 (n=54), 60%; for greater than or equal to 3 (n=45), 41%. A major breakpoint for outcome is 1-year Cr level=2.0. A power analysis was performed for the combined endpoint of graft loss and 1-year Cr level greater than 2, reached by 30% of patients. To avoid missing a reduction to 20% (actual decrease 33%) (alpha=0.05; power=0.8), 313 patients would be required per group. For a reduction to 15% (actual decrease 50%), 133 patients would be required.

CONCLUSIONS

Twelve-month Cr level is an accurate surrogate for long-term outcome. The use of a combined endpoint (graft loss and 12-month Cr level) allows trials to be performed without exorbitant numbers.

The clinical significance of antibody to vascular endothelial cells after renal transplantation

Vascular endothelial cells (ECs) are considered to be a primary target for injury in allograft rejection. However, the relationship between serum antibody activity to ECs and rejection episodes has not been examined extensively in renal transplantation. Twenty-two renal transplant recipients were included in this study. Serum antibody activity to vascular endothelial cells (AECA) was measured using a cellular enzyme-linked immunosorbent assay (ELISA) in which human umbilical vein endothelial cells (HUVEC) and human glomerular endothelial cells (HGEC) were preincubated with TNF-alpha used as target cells. Serum samples were obtained just before transplantation and once a week during the immediate 1-3-month post-transplantation period. There was a significant correlation between the presence of AECA against HGEC and rejection episodes (P < 0.05). Patients with multi-episodes of rejection showed significantly higher frequencies of AECA than patients with mono-episodic rejection (P < 0.0005). It should be noted that patients suffering from multi-episodes of rejection revealed higher AECA titres before transplantation. These findings imply that the HGEC-ELISA could be used as a prospective, informative test to identify patients with a higher risk of acute rejection in renal transplantation.

Interleukin-2 receptor monoclonal antibodies in renal transplantation: meta-analysis of randomised trials

OBJECTIVE

To study the effect of interleukin-2 receptor monoclonal antibodies on acute rejection episodes, graft loss, deaths, and rate of infection and malignancy in patients with renal transplants.

DESIGN

Meta-analysis of published data.

DATA SOURCES

Medline, Embase, and Cochrane library for years 1996-2003 plus search of medical editors' trial amnesty and contact with manufacturers of the antibodies.

SELECTION OF STUDIES

Randomised controlled trials comparing interleukin-2 receptor antibodies with placebo or no additional treatment in patients with renal transplants receiving ciclosporin based immunosuppression.

RESULTS

Eight randomised controlled trials involving 1871 patients met the selection criteria (although only 1858 patients were analysed). Interleukin-2 receptor antibodies significantly reduced the risk of acute rejection (odds ratio 0.51, 95% confidence interval 0.42 to 0.63). There were no significant differences in the rate of graft loss (0.78, 0.58 to 1.04), mortality (0.75, 0.46 to 1.23), overall incidence of infections (0.97, 0.77 to 1.24), incidence of cytomegalovirus infections (0.81, 0.62 to 1.04), or risk of malignancies at one year (0.82, 0.39 to 1.70). The different antibodies had a similar sized effect on acute rejection (test for heterogeneity P=0.7): anti-Tac (0.37, 0.16 to 0.89), BT563 (0.37, 0.1 to 1.38), basiliximab (0.56, 0.44 to 0.72), and daclizumab (0.46, 0.32 to 0.67). The reduction in acute rejections was similar for all ciclosporin based immunosuppression regimens (test for heterogeneity P=1.0).

CONCLUSIONS

Adding interleukin-2 receptor antibodies to ciclosporin based immunosuppression reduces episodes of acute rejection at six months by 49%. There is no evidence of an increased risk of infective complications. Longer follow up studies are needed to confirm whether interleukin-2 receptor antibodies improve long term graft and patient survival.

Impact of acute rejection episodes on long-term graft survival following simultaneous kidney-pancreas transplantation

Although it is well established that acute rejection is one of the major risk factors for chronic graft loss following kidney transplantation, its effect on long-term graft survival following simultaneous kidney-pancreas transplants (SKPTs) is less well known. We analyzed a large cohort of SKPTs and cadaver kidney transplants reported to the United Network for Organ Sharing database during 1988-97, to determine the impact of acute rejection episodes on long-term kidney and pancreas graft survival. Only patients whose kidney and pancreas grafts had survived for at least 1 year were included. Other potential risk factors influencing long-term graft survival were included in the analysis. Of the 4251 SKPTs, 45% had no acute rejection, 36% had kidney only rejection, 3% had pancreas only rejection, and 16% had both kidney and pancreas rejection within the 1st year post transplant. The 5-year kidney and pancreas graft survival rates adjusted for other risk factors were 91% and 85%, respectively; for those with no acute rejection episodes, 88% and 84%, respectively; for those with kidney only rejection, 94% and 83%, respectively; for those with pancreas only rejection; and 86% and 78%, respectively, for those with both kidney and pancreas rejection. The relative risk (RR) of kidney graft failure was 1.32 when acute rejection involved the kidney graft only, while the RR was 1.53 when the rejection involved both organs. We conclude that acute rejection episodes have a negative impact on the long-term kidney graft survival in the SKPT population similar to that in the cadaver kidney transplant population. Patients who had acute rejection episodes of both kidney and pancreas have the worst long-term graft survival.

Pre-transplant Th1 and post-transplant Th2 cytokine patterns are associated with early acute rejection in renal transplant recipients

In this retrospective study, we tried to define pre- and post-transplant immunological parameters that identify patients at risk for early acute rejection. Lymphocyte subpopulations and plasma levels of cytokines and neopterin were determined pre- and post-transplant in 32 renal transplant recipients with biopsy-proven early acute graft rejection. Recipients without early acute rejection served as controls. High pre-transplant interferon-gamma (IFN-gamma) plasma levels (p = 0.006), consistently high levels of neopterin early post-transplant (p = 0.008), a post-transplant switch from a Th1 to a Th2 cytokine pattern with decreasing IFN-gamma (p = 0.02), low CD8+ lymphocyte counts (p = 0.006) and consistently high CD19+ B lymphocyte counts were associated with acute rejection. Our data suggest that patients with a pre-transplant Th1 and an early post-transplant Th2 cytokine pattern are pre-disposed for early acute rejection.

The expression patterns of CD44 and CD45RB on peripheral blood T lymphocytes in the rejection of allogeneic murine skin transplantation

Until now, the rejection was diagnosed through a biopsy, but this method of diagnosis reflected the advanced tissue damage of the transplanted organ and contained the innate problem of being invasive. In relation, our research attempted to evaluate the viability of analyzing the surface antigens of the peripheral blood activated T lymphocytes after murine skin transplantation as a non-invasive and early diagnostic tool for diagnosis of rejection. After mouse skin was transplanted, the expression patterns of activated T lymphocyte markers, CD44 and CD45RB were analyzed along with T lymphocyte markers, CD3, CD4 and CD8 using flow cytometry. The skins from the tails of allogeneic BALB/c(H2d) mice and syngeneic C57BL/6J mice were transplanted to C57BL/6J(H2b) mice as test and control groups, respectively. Peripheral blood, which was sampled from the tail every other day from day 3 to day 15 was stained with anti-CD44 (or CD45RB), anti-CD4 (or CD8) and anti-CD3 monoclonal antibodies simultaneously, and analyzed by 3-color FACS. Rejection occurred only in the test group from day 8 to day 13 (median: day 10). Although the proportions of CD3(+) lymphocytes, CD4(+) lymphocytes and CD8(+) lymphocytes showed no difference, the total number of peripheral blood lymphocytes and the number of CD3(+) lymphocytes and CD8(+) lymphocytes decreased more sharply in the control after day 7. The proportion and the number of CD44(+)CD3(+)-lymphocytes, CD44(+)CD4(+)-lymphocytes and CD44(+)CD4(+)CD3(+)-lymphocytes began to increase after day 7, to peak on day 11, and then to decrease, showing a significant difference. The proportion and number of CD44(+)CD8(+)-lymphocytes and CD44(+)CD8(+)CD3(+)-lymphocytes showed similar trends. No significant difference was observed in any subsets of the CD45RB antigen. The analysis of the expression patterns of surface antigen CD44 on peripheral blood T lymphocytes using flow cytometry is sensitive, safe, easily repeatable and controllable, and, therefore, can be considered a promising tool for the diagnosis of rejection. However, the clear change in CD44 occurred between day 9 and day 13, when rejection was observed grossly. Therefore, it is regarded more useful as a screening test or follow-up indicator rather than as an early diagnostic tool.

A three-arm study comparing immediate tacrolimus therapy with antithymocyte globulin induction therapy followed by tacrolimus or cyclosporine A in adult renal transplant recipients

BACKGROUND

Induction therapy with antithymocyte globulin (ATG) reduces the incidence of acute rejection after transplantation. A study was undertaken to assess the efficacy and safety of ATG induction on tacrolimus-based and cyclosporine A (CsA)-based therapies compared with immediate tacrolimus triple therapy in kidney transplant recipients.

METHODS

In a 6-month, open-label, randomized, prospective study conducted in 30 European centers, 555 renal transplant patients were randomly assigned to tacrolimus triple therapy (Tac triple, n=185), ATG induction with tacrolimus (ATG-Tac, n=186), or ATG induction with CsA microemulsion (ATG-CsA, n=184); all were combined with azathioprine and corticosteroids. The primary endpoint was incidence and time to first acute rejection episode confirmed by biopsy.

RESULTS

Patient demographics and clinical parameters at baseline were similar. Patient and graft survival rates were similar in all groups. The incidence of clinically apparent acute rejection was significantly higher (P=0.003) for Tac triple (33.0%) compared with ATG-Tac (22.6%) and the incidence for ATG-Tac was significantly lower (P=0.004) than for ATG-CsA (37.0%). The incidences of acute rejection confirmed by biopsy (primary endpoint) were 25.4%, 15.1%, and 21.2% for Tac triple, ATG-Tac, and ATG-CsA, respectively (Tac triple vs. ATG-Tac, P=0.004). The incidences of corticosteroid-resistant acute rejection were 7.0% (Tac triple), 4.8% (ATG-Tac), and 10.9% (ATG-CsA) (ATG-Tac vs. ATG-CsA, P=0.038). In the ATG groups, the incidences of leukopenia, thrombocytopenia, serum sickness, fever, and cytomegalovirus infection were significantly higher (P<0.05).

CONCLUSIONS

Acute rejection was significantly lower in the ATG-Tac group compared with the ATG-CsA and Tac triple groups. Significantly more hematologic and infectious adverse events were observed in both ATG induction groups.

Can a pharmacokinetic approach to immunosuppression eliminate ethnic disparities in renal allograft outcome?

Although renal allograft outcome correlates more closely with area under the concentration time curve (AUC) for cyclosporin (CsA) compared with the 12-h trough level (C0), few studies have prospectively evaluated pharmacokinetic monitoring in kidney transplantation. This paper describes a study designed to evaluate the impact of a novel approach to CsA-based immunosuppression on ethnic differences in renal allograft outcome. Sixty (32 African Americans and 28 Caucasians) renal transplant recipients were treated with cyclosporin-based triple therapy. Morning and evening doses were independently adjusted to reach an AUC0-12 of 6600-7200 ng h/mL and a C0 of 250-325 ng/mL, respectively. AUCs were measured within 48 h of starting CsA, and as often as necessary to maintain target levels. Only two patients experienced significant adverse events related to immunosuppression. One (Caucasian) developed haemolytic uremic syndrome and was converted to tacrolimus, while another (African American) developed acute vascular rejection. One graft was lost (Caucasian) due to death with a functioning graft. An average of 8 AUCs (range 5-13) were measured in the first 3 months. AUCs were significantly higher in African Americans compared with Caucasians only in the first and second month. C0 values were similar in both groups throughout the study period. A pharmacokinetic approach to immunosuppression allows individualization of CsA exposure, and appears to reduce ethnic disparities in renal allograft outcome.

Protocol core needle biopsy and histologic Chronic Allograft Damage Index (CADI) as surrogate end point for long-term graft survival in multicenter studies

This study is an investigation of whether a protocol biopsy may be used as surrogate to late graft survival in multicenter renal transplantation trials. During two mycophenolate mofetil trials, 621 representative protocol biopsies were obtained at baseline, 1 yr, and 3 yr. The samples were coded and evaluated blindly by two pathologists, and Chronic Allograft Damage Index (CADI) score was constructed. At 1 yr, only 20% of patients had elevated (>l.5 mg/100 ml) serum creatinine, whereas 60% of the biopsies demonstrated an elevated (>2.0) CADI score. The mean CADI score at baseline, 1.3 +/- 1.1, increased to 3.3 +/- 1.8 at 1 yr and to 4.1 +/- 2.2 at 3 yr. The patients at 1 yr were divided into three groups, those with CADI <2, between 2 and 3.9, and >4.0, the first two groups having normal (1.4 +/- 0.3 and 1.5 +/- 0.6 mg/dl) and the third group pathologic (1.9 +/- 0.8 mg/dl) serum creatinine. At 3 yr, there were no lost grafts in the low CADI group, six lost grafts (4.6%) in the in the elevated CADI group, and 17 lost grafts (16.7%) in the high CADI group (P < 0.001). One-year histologic CADI score predicts graft survival even when the graft function is still normal. This observation makes it possible to use CADI as a surrogate end point in prevention trials and to identify the patients at risk for intervention trials.

Neutrophils mediate parenchymal tissue necrosis and accelerate the rejection of complete major histocompatibility complex-disparate cardiac allografts in the absence of interferon-gamma

A major feature of acute rejection of cardiac allografts is an intense mononuclear cell infiltration accompanied by interferon (IFN)-gamma production. In the current study we tested the role of IFN-gamma in acute rejection of allografts by comparing the histopathology of rejection in wild-type versus IFN-gamma-/- recipients of major histocompatibility complex-mismatched cardiac grafts. Wild-type recipients rejected the allografts at days 8 to 9 after transplant but rejection was accelerated 2 to 3 days in IFN-gamma-deficient recipients. During rejection in wild-type recipients, the allografts were heavily infiltrated with CD8+ T cells and other mononuclear cells. In contrast, allografts in IFN-gamma-deficient recipients had few T cells but an intense neutrophil infiltration accompanied by extensive graft parenchymal necrosis. No difference in expression levels of neutrophil chemoattractants including Groalpha/KC, MIP-2, GCP-2, and MIP-1alpha, was observed in allografts retrieved from wild-type and IFN-gamma-/- recipients. Depletion of neutrophils from IFN-gamma-deficient recipients delayed rejection until days 8 to 10 after transplant and restored the histopathology of acute allograft rejection to that observed in allografts rejected by wild-type recipients. These results indicate the potent regulatory properties of IFN-gamma during acute rejection directed at neutrophil infiltration into allografts and mediating graft tissue necrosis.

Randomized double-blind study of immunoprophylaxis with basiliximab, a chimeric anti-interleukin-2 receptor monoclonal antibody, in combination with mycophenolate mofetil-containing triple therapy in renal transplantation

BACKGROUND

Acute rejection remains a major problem in renal transplantation. Immunoprophylaxis with basiliximab (Simulect) has achieved significant reductions in acute rejection episodes in renal allograft recipients receiving dual immunosuppression. This study explored the tolerability and cumulative benefit of combining basiliximab with triple-drug therapy-cyclosporine (USP Modified, Neoral), mycophenolate mofetil, and steroids.

METHODS

In a randomized, double-blind, placebo-controlled, multicenter study, 123 kidney transplant recipients received either basiliximab at 20 mg before transplantation (day 0) and 20 mg on day 4 (n=59), or placebo (n=64). All received triple-drug immunosuppression and were followed for 6 months.

RESULTS

Tolerability of basiliximab was equivalent to placebo, with no increase in serious adverse events, infection, malignancy, or posttransplant lymphoproliferative disorder. At 6 months, there were trends in favor of basiliximab over placebo in the incidences of first biopsy-confirmed acute rejection (15.3% vs. 26.6%, P=NS) and of acute rejection treated with antibody (5.1% vs. 15.6%, P=NS). Kaplan-Meier estimates at 4 weeks and 6 months were significantly in favor of basiliximab treatment for first acute rejection, biopsy-confirmed rejection, rejection episodes treated with antibody therapy, and treatment failure. Renal function improved more rapidly in the basiliximab group, with mean creatinine clearance at week 2 being 54.7 mL/min versus 43.2 mL/min for placebo (P=0.034). At 12 months, patient survival was 100% in both groups; graft survival was 94.9% with basiliximab and 92.2% with placebo.

CONCLUSIONS

Basiliximab immunoprophylaxis is safe, well tolerated, and shows a trend toward reduction in number of acute rejection episodes in renal transplant patients receiving cyclosporine, mycophenolate mofetil, and steroids.

Long-term use of mycophenolate mofetil is associated with a reduction in the incidence and risk of late rejection

To evaluate the association of long-term continuous (minimum 1 year) mycophenolate mofetil (MMF) vs. azathioprine (AZA) therapy with the incidence of late acute rejection, we analyzed 47 693 primary renal allograft recipients reported to the United States Renal Data System between 1988 and 1998. The primary study endpoint was acute rejection beyond 1 year after transplantation. Univariate Kaplan-Meier analysis and multivariate Cox proportional hazard models were used to investigate the risk of reaching the study endpoints. All multivariate analyses were corrected for potential confounding covariates. Mycophenolate mofetil was associated with a 65% decreased risk of developing late acute rejection as compared to AZA (RR = 0.35, CI 0.27-0.45, p < 0.001). The incidence of acute rejection episodes at 2 and 3 years post-transplantation was significantly lower in the MMF group (0.9% at 2 years, 1.1% at 3 years) than the AZA group (6.1% at 2 years, 9.3% at 3 years). In the primary vs. repeat late rejection analysis, MMF patients exhibited a decreased late acute rejection risk of 72% (RR = 0.28, p < 0.001) and 60%, respectively (RR = 0.40, p < 0.001). In African Americans, the late acute rejection risk was 70% lower in MMF patients than AZA patients (RR = 0.30, p < 0.001). Further study is indicated to determine the optimal duration of MMF therapy after renal allograft transplantation.

The effect of two different cyclosporine formulations on the long-term progression to chronic rejection in renal allograft recipients

INTRODUCTION

The introduction of the microemulsion formulation of cyclosporine (CsA) (Neoral-NEO) has been shown to provide improved absorption and less intrapatient variability than the previous formulation (Sandimmune-SIM) in kidney transplant recipients. It has been suggested that the use of the microemulsion formulation results in less acute rejection, and therefore permits better long-term transplant outcomes. Our aim was to determine whether the microemulsion formulation of cyclosporine has reduced the long-term (5 yr or more) rates of chronic rejection (allograft nephropathy) in a renal transplant population.

METHODS

The study population included 792 (508 cadaveric and 284 living donor) transplants performed in 786 patients at the Cleveland Clinic Foundation and its affiliate hospitals between July 1, 1987 and July 1, 1998. Patients who were less than 18-yr-old or had less than 12 months of graft function were excluded from the analysis. Over 90% of the cadaveric and 11% of the live donor recipients were given an induction antibody. A total of 591 patients were given the SIM formulation and 201 the NEO formulation of cyclosporine. Additional maintenance therapy included either azathioprine or mycophenolate mofetil, and steroids. All patients were followed to graft loss, death, or return to dialysis. The NEO group was followed until December 2001. The diagnosis of acute rejection was biopsy confirmed in >92% of cases. Chronic rejection was identified by clinical and biopsy criteria. Demographic and clinical data was collected from medical records, interviews, and phone contact with patients and treating physicians.

RESULTS

The mean follow-up was 84 +/- 31 months for the SIM group, and 54 +/- 14 months for the NEO group. At 70 months there was no significant difference (p = 0.17) - actuarial patient survival between the SIM (90.7%) vs. the NEO (93%) treated patients. In addition, at 70 months there was no significant difference (p = 0.55) in death censored actuarial graft survival between the SIM (84.3%) and the NEO treated (85.7%) patients. The acute rejection-free rate was 10% higher for the NEO vs. the SIM patients (79 vs. 69%, p = 0.0004). Chronic rejection was diagnosed in 141 of 591 (24%) of the SIM patients and in 56 of 201 (28%) of the NEO patients (p = ns). At 5 yr the mean serum creatinine (mg/dL) was 2.07 +/- 1.69 for the SIM and 2.15 +/- 1.61 for the NEO patients (p = ns).

CONCLUSIONS

The use of the microemulsion formulation of CsA has led to the improved delivery of the parent drug, and a decrease in the number of acute rejection episodes post-transplant. However, patient and graft survival, renal function, and progression to chronic allograft nephropathy at 5 yr were no different. The advantages of greater drug exposure from the microemulsion formulation may be counterbalanced by increased drug induced nephrotoxicity over time.