Influence of surveillance renal allograft biopsy on diagnosis and prognosis of polyomavirus-associated nephropathy

BACKGROUND

Polyomavirus-associated nephropathy (PVAN) is an increasingly prevalent cause of allograft dysfunction.

METHODS

In 18 histologically proven cases of PVAN managed by reduced immunosuppression, monitoring of serum creatinine, and repeated biopsy, graft outcomes were correlated with clinical and histologic indices. Six months postdiagnosis the status of each graft was classified as poor (N = 7) or satisfactory (N = 11). Poor transplant status was defined as graft loss, increased severity of PVAN on repeat biopsy, or serum creatinine>3.0 mg/dL. Diagnosis resulted from either surveillance allograft biopsies (N = 8) or biopsies performed for increased serum creatinine (nonsurveillance, N = 10).

RESULTS

The surveillance biopsy group was more likely than the nonsurveillance group to have satisfactory graft status at 6 months (eight of eight vs. three of ten, P = 0.004) and had significantly lower serum creatinine at diagnosis, 3, and 6 months. Histologic scoring for chronic interstitial and tubular injury was lower in diagnostic surveillance biopsies compared to nonsurveillance biopsies (P = 0.01). Satisfactory transplant status was also associated with reduced or absent virus on repeat biopsy (P = 0.01). Poor transplant status was associated with a higher frequency of recipientneg/donorpos cytomegalovirus (CMV) serology (71% vs. 9%, P = 0.01).

CONCLUSION

Surveillance allograft biopsy provides an important means for earlier detection of PVAN and permits timely alterations to immunosuppression. Early diagnosis is associated with a lesser degree of interstitial fibrosis at diagnosis and lower baseline and subsequent serum creatinine.

Overcoming a positive crossmatch in living-donor kidney transplantation

Many patients who have an otherwise acceptable living-kidney donor do not undergo transplantation because of the presence of antibodies against the donor cells resulting in a positive crossmatch. In the current study, 14 patients with a positive cytotoxic crossmatch (titer </= 1 : 16) against their living donor underwent a regimen including pretransplant plasmapheresis, intravenous immunoglobulin, rituximab and splenectomy. Eleven of 14 grafts (79%) are functioning well 30-600 days after transplantation. Two grafts were lost to accelerated vasculopathy and one was lost to death with good function. No hyperacute or cellular rejections occurred. Antibody-mediated rejection occurred in six patients [two clinical (14%) and four subclinical (29%)] and was reversible with plasmapheresis and steroids. Our results suggest that selected crossmatch-positive patients can be transplanted successfully with living-donor kidney allografts, using a protocol of pretransplant plasmapheresis, intravenous immunoglobulin, rituximab and splenectomy. Longer follow-up will be needed, but the absence of anti-donor antibody and good early outcomes are encouraging.

Prospective, randomized, multi-center trial of antibody induction therapy in simultaneous pancreas-kidney transplantation

A randomized, multicenter, prospective study was conducted at 18 pancreas transplant centers in the United States to determine the role of induction therapy in simultaneous pancreas-kidney (SPK) transplantation. One hundred and 74 recipients were enrolled: 87 recipients each in the induction and noninduction treatment arms. Maintenance immunosuppression consisted of tacrolimus, mycophenolate mofetil, and corticosteroids. There were no statistically significant differences between treatment groups for patient, kidney, and pancreas graft survival at 1-year. The 1-year cumulative incidence of any treated biopsy-confirmed or presumptive rejection episodes (kidney or pancreas) in the induction and noninduction treatment arms was 24.6% and 31.2% (p = 0.28), respectively. The 1-year cumulative incidence of biopsy-confirmed, treated, acute kidney allograft rejection in the induction and noninduction treatment arms was 13.1% and 23.0% (p = 0.08), respectively. Biopsy-confirmed kidney allograft rejection occurred later post-transplant and appeared to be less severe among recipients that received induction therapy. The highest rate of Cytomegalovirus (CMV) viremia/syndrome was observed in the subgroup of recipients who received T-cell depleting antibody induction and received organs from CMV serologically positive donors. Decisions regarding the routine use of induction therapy in SPK transplantation must take into consideration its differential effects on risk of rejection and infection.

Improved scoring system to assess adult donors for cadaver renal transplantation

We previously proposed a quantitative approach to assess donor organs for cadaver renal transplantation. To improve on our original scoring system, we studied 34 324 patients who received cadaver renal transplants from adult donors between 1994 and 1999 and were reported to the UNOS Scientific Renal Transplant Registry. A scoring system was developed from five donor variables (age, 0-25 points; history of hypertension, 0-4; creatinine clearance before procurement, 0-4; cause of death, 0-3; HLA mismatch, 0-3) that showed a significant correlation with renal function and long-term graft survival. Cadaver kidneys were stratified by cumulative donor score: grade A, 0-9 points; grade B, 10-19; grade C, 20-29; and grade D, 30-39. The influence of donor score on renal function and graft survival was most severe above 20 points, designated 'marginal' kidneys. In summary, a donor scoring system developed from a large population database was useful in predicting outcome after cadaver renal transplantation. The improved system provides a quantitative approach to evaluation of marginal kidneys and may improve allocation of these organs in cadaver renal transplantation.

Kidney transplantation without calcineurin inhibitors using sirolimus

INTRODUCTION

With the introduction of new immunosuppressive medicines, it has become possible to determine the extent to which nephrotoxic medicines contribute to CAN. The aim of this study is to compare the safety and efficacy of calcineurin inhibitor (CI) free immunosuppression in a prospective, randomized trial comparing sirolimus-mycophenolate mofetil (MMF)-prednisone to tacrolimus- MMF-prednisone.

METHODS

Patients are randomized at the time of transplant to receive either tacrolimus (target level 12 to 15 ng/mL in the first month) or sirolimus (target level 12 to 18 ng/mL in the first month). All patients also receive MMF (750 mg bid) and prednisone tapered to 10 mg/d by 3 months and thymoglobulin induction (1.5 mg/kg/d on days 0, 1, 2, 4 and 6).

RESULTS

At this point we have 4-month follow-up in 85 patients. The acute rejection rate is 7.5% (3/40) in the tacrolimus group and 6.7% (3/45) in the sirolimus group. We have discontinued sirolimus in eight patients so far, with wound complications being the most common indication. Renal function appears to be better in the sirolimus group at 1 month after transplantation, but the difference is not statistically significant.

CONCLUSIONS

While longer follow-up is needed, these results demonstrate that total avoidance of CI can be achieved with extremely low acute cellular rejection rates using sirolimus-based immunosuppression in combination with thymoglobulin, MMF, and prednisone.

ABO-incompatible kidney transplantation using both A2 and non-A2 living donors

BACKGROUND

Given the scarcity of cadaveric organs, efforts are intensifying to increase the availability of living donors. The current study assessed the feasibility of using ABO-incompatible living-donor kidneys to expand the donor pool.

METHODS

The authors performed 18 ABO-incompatible living-donor kidney transplants between May 1999 and April 2001. Ten patients received living-donor kidneys from A2 and eight patients received kidneys from non-A2 blood group donors. Immunosuppression consisted of Thymoglobulin antibody induction, tacrolimus, mycophenolate mofetil, and prednisone. Eight non-A2 and two A2 kidney recipients also received a pretransplant conditioning regimen of four plasmapheresis treatments followed by intravenous immunoglobulin and splenectomy at the time of transplantation. Antidonor blood group antibody titer was measured at baseline, pretransplant, at 1- to 3-month and 1-year follow-up, and at the time of diagnosis of antibody-mediated rejection.

RESULTS

No hyperacute rejection episodes occurred. One-year graft and patient survival rates in the 18 ABO-incompatible recipients were only slightly lower than those of 81 patients who received ABO-compatible kidney transplants during the same period (89% vs. 96% and 94% vs. 99%, respectively). Glomerular filtration rate and serum creatinine levels did not differ between the groups. Antibody-mediated rejection occurred in 28% of ABO-incompatible recipients, and was reversible with plasmapheresis, intravenous immunoglobulin, and increasing immunosuppression in all patients except one.

CONCLUSIONS

ABO-incompatible living donor kidney transplants can achieve an acceptable 1-year graft survival rate using an immunosuppressive regimen consisting of Thymoglobulin induction, tacrolimus, mycophenolate mofetil, and prednisone combined with pretransplant plasmapheresis, intravenous immunoglobulin, and splenectomy.

Forskolin suppresses insulin gene transcription in islet beta-cells through a protein kinase A-independent pathway

This work was designed to evaluate the effect of cAMP on insulin gene regulation. We studied the effects of forskolin on insulin gene transcription in the INS-1 beta-cell line, confirming key results in primary cultures of human islet cells. Forskolin increased intracellular cAMP and cAMP-responsive element-binding activity. Insulin gene transcription was studied using a reporter construct in which the human insulin promoter was fused to luciferase. When cells were treated with forskolin for 12 h, insulin promoter activity was decreased 2- to 3-fold, whereas islet amyloid polypeptide promoter activity was significantly increased. This effect of forskolin on the insulin gene was time- and concentration-dependent, and was mimicked by 8-bromo-cAMP. Mutagenesis of the CRE-like elements in the insulin promoter had no effect on the forskolin-induced suppression, but dramatically decreased basal insulin promoter activity. Inhibition of PKA with H-89 also did not reverse the forskolin-induced suppression of insulin transcription. However, this effect was completely reversed by inhibition of cellular MAP kinase activity with PD98059 or U0126. These results demonstrate that forskolin suppresses insulin transcription in INS-1 cells through a PKA-independent mechanism that probably involves MAP kinase signalling.

Changes in intragraft gene expression secondary to ischemia reperfusion after cardiac transplantation

BACKGROUND

Ischemia-reperfusion (I/R) injury in transplanted tissue is associated with changes in intragraft cytokines, chemokines, and adhesion molecules. The aim of this study was to perform a comprehensive analysis of gene expression in cardiac grafts secondary to I/R using microarray technology.

METHODS

Heterotopic brown Norway rat cardiac isografts were removed on postoperative day (POD) 3, 5, and 7. RNA was extracted, hybridized on U34A-Affymetrix high-density gene expression arrays, and compared with nontransplanted hearts using the log-average ration (LAR) and Student test.

RESULTS

Of the approximately 8,799 transcripts tested on each chip, 557 were significantly increased by POD5, with fewer induced transcripts observed on POD3 (46) and POD7 (32). The most significantly induced transcripts included MHC class II molecules, interferon-gamma inducing factor, apolipoprotein E, and cathepsin S. In contrast, the highest number of down-regulated transcripts was seen on POD3 (746) with fewer transcripts down-regulated by POD5 (162) and POD7 (298). Down-regulated transcripts included those involved in cellular metabolism: monoamine oxidase-A, mitochondrial-A synthase complex, and cytochrome oxidase subunit. By POD7, oxidative stress inducible protein tyrosine phosphatase and vascular endothelial cell growth factor were significantly decreased in transplanted isografts. Reverse-transcriptase polymerase chain reaction (RT-PCR) data on 10 transcripts agreed with the microarray results.

CONCLUSIONS

Microarrays using LAR analyses generally agree with previous data regarding intragraft changes during I/R injury but provide a larger number of molecules for future study. Although the largest number of down-regulated genes was seen early, the I/R effect may be continuing in that many transcripts remain down-regulated 7 days after transplantation.

Chronic renal dysfunction late after liver transplantation

With the increasing success of liver transplantation, more patients are developing late complications such as renal dysfunction. The goal of the current study was to assess the prevalence of renal dysfunction years after liver transplantation and to identify patients at risk for the development of this complication. Of the 527 liver transplantations performed at our institution between April 1990 and October 1998, 353 had pretransplantation and posttransplantation glomerular filtration rate (GFR) determinations by iothalamate clearance. From this entire group, 198 patients had actual 4-year follow-up and 52 had actual 6-year follow-up. In addition, 191 of these patients had intensive follow-up with GFR measurements pretransplantation and at 1 and 3 years posttransplantation (complete follow-up group). All patients received either tacrolimus- or cyclosporine-based immunosuppression. The overall mean GFR levels in both of these groups was acceptable and was not different in cyclosporine- versus tacrolimus-based immunosuppressive regimens. Renal dysfunction was progressive, with 27.5% of patients in the intensive group having a GFR < 40 mL/min/body surface area 5 years after transplantation. GFR pretransplantation did not correlate well with late renal function; however, GFR at 1 year identified patients with subsequent renal dysfunction. The cumulative incidence of renal failure for the entire group was 6.25% at 7 years and 10% at 10 years. Renal dysfunction is a major late complication after liver transplantation. The GFR at 1 year correlates best with late renal function. Patients with a low GFR at 1 year (< 40 mL/min/BSA) are a high-risk group that might benefit from early therapeutic interventions aimed at preventing subsequent renal failure.

Chronic renal dysfunction late after liver transplantation

With the increasing success of liver transplantation, more patients are developing late complications such as renal dysfunction. The goal of the current study was to assess the prevalence of renal dysfunction years after liver transplantation and to identify patients at risk for the development of this complication. Of the 527 liver transplantations performed at our institution between April 1990 and October 1998, 353 had pretransplantation and posttransplantation glomerular filtration rate (GFR) determinations by iothalamate clearance. From this entire group, 198 patients had actual 4-year follow-up and 52 had actual 6-year follow-up. In addition, 191 of these patients had intensive follow-up with GFR measurements pretransplantation and at 1 and 3 years posttransplantation (complete follow-up group). All patients received either tacrolimus- or cyclosporine-based immunosuppression. The overall mean GFR levels in both of these groups was acceptable and was not different in cyclosporine- versus tacrolimus-based immunosuppressive regimens. Renal dysfunction was progressive, with 27.5% of patients in the intensive group having a GFR < 40 mL/min/body surface area 5 years after transplantation. GFR pretransplantation did not correlate well with late renal function; however, GFR at 1 year identified patients with subsequent renal dysfunction. The cumulative incidence of renal failure for the entire group was 6.25% at 7 years and 10% at 10 years. Renal dysfunction is a major late complication after liver transplantation. The GFR at 1 year correlates best with late renal function. Patients with a low GFR at 1 year (< 40 mL/min/BSA) are a high-risk group that might benefit from early therapeutic interventions aimed at preventing subsequent renal failure.

Survival of mandatorily shared cadaveric kidneys and their paybacks in the zero mismatch era

BACKGROUND

The United Network for Organ Sharing has mandated the national sharing of well-matched cadaveric kidneys with payback to the national pool. On March 6, 1995, the policy was extended to include sharing of cadaveric kidneys for which there is a recipient with a 0-HLA mismatch (0-MM). However, the beneficial effects of this policy have been questioned. To address these concerns, we analyzed the effects of this system on graft survival, cold ischemia time, and the transplantation of highly sensitized patients during the 0-MM era.

METHODS

We analyzed cadaveric solitary kidney transplant data in the OPTN/The United Network for Organ Sharing database. Cox proportional hazards analyses were conducted on 29,401 transplants performed between March 6, 1995 and December 31, 1998 to assess the effects of mandatory sharing and paybacks on graft outcome. We also compared the outcome of pairs of kidneys in which one was shared as either an 0-MM kidney (n=833) or as a payback (n=440) and the mate was transplanted locally.

RESULTS

Overall, 36% of kidneys were shared, 15.6% as 0-MM and 20.4% as paybacks or other shares. Although the sharing of 0-MM kidneys significantly increased cold ischemia time, the risk of graft loss was significantly decreased. The survival of payback kidneys was not significantly different from other shared kidneys. Sharing 0-MM kidneys appeared to increase the chances of transplantation of sensitized patients and 47% of the kidneys transplanted in patients with a panel reactive antibody of more than 80% were from 0-MM donors.

CONCLUSIONS

National sharing of 0-MM kidneys appears to lead to a small but significant improvement in intermediate-term graft survival despite increasing cold ischemia time. The current policy also increases access of highly sensitized patients to transplantation.

Prospective, randomized evaluation of a cuffed expanded polytetrafluoroethylene graft for hemodialysis vascular access

BACKGROUND

A cuffed expanded polytetrafluoroethylene (ePTFE) hemodialysis graft was developed to address the problem of recurrent stenosis at the graft-vein anastomosis. The purpose of this study was to compare graft patency and blood flow rates of cuffed and noncuffed (standard) ePTFE grafts placed for hemodialysis access.

METHODS

Forty-eight patients were prospectively randomized and followed for up to 24 months after placement of a cuffed or standard ePTFE graft for hemodialysis access. Study end points included time to graft failure and blood flow rates on hemodialysis.

RESULTS

Risk factors for graft failure were similar in both groups. However, the overall incidence of graft failure was significantly lower in the cuffed ePTFE graft group (P =.039). Graft patency rates in the cuffed versus standard groups were 64% versus 32% at 12 months (P =.037) and 58% versus 21% at 24 months (P =.0213). No cuffed ePTFE graft failed as a result of venous outflow stenosis. Average graft flow rates were similar when first measured 3 months postoperatively (845 mL/min, cuffed vs 715 mL/min, standard; P =.51) but declined more rapidly in the standard group (12 months, 623 vs 253 mL/min [P =.037]; 24 months, 531 vs 121 mL/min [P =.012]).

CONCLUSIONS

The cuffed ePTFE graft was associated with increased blood flow rates during hemodialysis and improved graft patency compared with a standard ePTFE graft. Our results suggest a beneficial effect of the cuffed venous geometry for hemodialysis vascular access.

Subclinical rejection in tacrolimus-treated renal transplant recipients

BACKGROUND

Subclinical rejection, defined as histologic acute rejection in the absence of graft dysfunction, has been suggested as a cause of chronic allograft rejection. In cyclosporine-treated patients, the incidence of subclinical rejection 3 months after transplant is reported to be approximately 30%. The intent of our study was to determine the incidence of subclinical rejection in tacrolimus-treated renal allograft recipients.

METHODS

We prospectively studied the incidence of subclinical rejection on surveillance biopsies performed 3 months after transplantation in 114 patients transplanted between September 1, 1998 and November 30, 2000. All patients received tacrolimus, mycophenolate mofetil, and prednisone, and 56% received antibody induction.

RESULTS

Subclinical rejection was detected in 2.6% of patients (3/114, 95% confidence interval 0.5-7.5%). Borderline changes were detected in 11% (12/114). Subclinical rejections were treated with bolus methylprednisolone.

CONCLUSIONS

The incidence of subclinical rejection early after kidney transplantation is extremely low in tacrolimus-treated patients in whom early rejections are aggressively treated, suggesting that surveillance biopsies may not be necessary with this regimen.

Can a transplanted living donor kidney function equivalently to its native partner?

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

Thymoglobulin induction decreases rejection in solitary pancreas transplantation

BACKGROUND

Solitary pancreas transplants, both pancreas transplant alone (PTA) and pancreas after kidney (PAK), have higher rejection rates and lower graft survivals than simultaneous pancreas-kidney transplants (SPK). The aim of this study is to compare three different antibody induction regimens in solitary pancreas transplant recipients and to assess the role of surveillance pancreas biopsies in the management of these patients.

METHODS

Solitary pancreas transplant recipients between 01/98 to 02/00 (n=29) received induction with either daclizumab (1 mg/kg on day 0, 7, 14), OKT 3 (5 mg/day x0-7), or thymoglobulin (1.5 mg/kg/day x0-10). Maintenance immunosuppression was similar for the three groups. All rejections were biopsy-proven either by surveillance/protocol or when clinically indicated.

RESULTS

The 1-year graft survival was 89.3% overall and 91.7% in the thymoglobulin group. Thymoglobulin significantly decreased rejection in the first 6 months when compared with OKT3 or daclizumab (7.7 vs. 60 vs. 50%). Acute rejections were seen on surveillance biopsies in the absence of biochemical abnormalities in 40% of patients.

CONCLUSIONS

Thymoglobulin induction regimen led to a low incidence of acute rejection and a high rate of graft survival in solitary pancreas transplants. In addition, surveillance biopsies were useful in the detection of early acute rejection in the absence of biochemical abnormalities.

Cyclosporine elimination in the presence of TOR inhibitors: effects on renal function, acute rejection, and safety

Sirolimus in combination with cyclosporine reduces the incidence of acute rejection in renal transplant recipients when administered in double- or triple-therapy immunosuppressive regimens. Sirolimus administered as primary therapy has a beneficial effect on renal function, and the frequency of rejection episodes is similar to that of primary immunosuppression with cyclosporine. A strategy that may result in a more benign immunologic course with a substantially beneficial effect on renal function is to administer sirolimus and a calcineurin inhibitor early after transplantation, thereby promoting immunologic adaptation, and then to withdraw the calcineurin inhibitor at some point after transplantation to prevent nephrotoxicity. This article examines the results of this approach in recent studies that evaluated the effect of cyclosporine withdrawal on renal function, acute rejection, and safety in patients treated with sirolimus. Two open-label randomized trials of cyclosporine withdrawal were conducted in the United States, Canada, Europe, and Australia. In one of the studies, graft survival, patient survival, and the incidence of acute rejection at 6 months posttransplantation were not statistically significantly different between the patients receiving cyclosporine and the group that had undergone cyclosporine withdrawal. Furthermore, significantly better renal function was observed in the patients who underwent cyclosporine withdrawal compared with patients who continued to receive full-dose cyclosporine. These studies indicate that cyclosporine withdrawal has a beneficial effect on renal function without a significant increase in the incidence of acute rejection episodes.

Donor scoring system for cadaveric renal transplantation

We studied early renal function in 241 consecutive patients who received cadaveric renal transplants at two different transplantation centers (group 1, n = 90; group 2, n = 151). Univariate and multivariate analyses of data from group 1 showed a significant correlation between seven donor variables and early renal function after cadaveric renal transplantation. A scoring system was developed from these seven donor variables (cause of death, 0-6 points; history of hypertension, 0-6; final creatinine clearance before procurement, 0-6; age, 0-6; history of diabetes mellitus, 0-3; cold ischemia time, 0-3; and severity of renal artery plaque, 0-3). Data from group 2 were used to validate the donor scoring system and stratify cadaver kidneys on the basis of score: grade A, 0-5 points; grade B, 6-10; grade C, 11-15; and grade D, 16-32. A significant decline in early renal function was observed with increasing donor score and grade of cadaver kidney. In conclusion, a donor scoring system based on information available at the time of procurement can be used to estimate early graft function after cadaveric renal transplantation and may assist in the allocation of marginal organs.

Preliminary experience with a cuffed ePTFE graft for hemodialysis vascular access

The purpose of this study was to determine graft patency and blood flow rates in recipients of a new cuffed ePTFE graft (Venaflo graft) used for hemodialysis access. A pilot study was conducted with 12 (7 men, 5 women) consecutive patients (age range, 36-76 yr; mean, 65 yr). All patients were recipients of a new cuffed PTFE graft placed for hemodialysis access. Seven were high risk because of a prior history of clotted hemodialysis accesses (1-6; mean, 3.3). Blood flow rates were determined by ultrasound dilution technique at 3 month intervals. One year and 2 year overall graft patency rates were 90.9% and 68.2%, respectively. One graft (high risk, six prior grafts) was lost to thrombosis in the first year; two grafts (one high risk, four prior grafts) were lost to thrombosis in the second year of follow-up. No graft thrombosis resulted from stenosis at the graft-vein anastomosis. Blood flow rates ranged from 550 to 2,110 ml/min (mean, 1,086 ml/min; n = 8) when first measured 3 months after graft placement. Similar flow rates were observed at 12 months (mean, 1,043 ml/min; n = 7) and 24 months (mean, 1,014 ml/min; n = 4) in grafts available for comparison. Dialysis flow rates in excess of 350 ml/min were possible with all patent grafts. A cuffed ePTFE graft provided stable blood flow and satisfactory graft patency during 2 years of follow-up, even in high risk patients with a prior history of vascular access thrombosis.

alpha4 integrin in islet allograft rejection

BACKGROUND

Adhesion molecules are involved in multiple steps of the continuum of allograft rejection. We studied the effects of blockade of the interactions between alpha4 integrin and its ligands, vascular cell adhesion molecule-1 (VCAM-1) and fibronectin, on allograft survival.

METHODS

Streptozotocin-induced diabetic CBA (H-2k) mice received islet transplants from BALB/c (H-2d) donors. Recipient mice were treated with antibodies against alpha4 integrin (PS/2), VCAM-1 (MK 2.7), and a peptide corresponding to the binding site of alpha4 integrin on fibronectin (connecting segment 1 peptide, CS1-peptide). Graft function was measured by daily tail vein blood glucose levels, with rejection defined as the return of hyperglycemia. Graft-bearing kidneys were removed for immunohistochemical analysis.

RESULTS

Treatment with anti-alpha4 integrin antibody, anti-VCAM-1 antibody, or with CS1-peptide led to long-term survival of islet allografts. Recipients with long-surviving islet grafts did not show tolerance, in that they rejected a second donor-type islet allograft. Although both anti-alpha4 integrin antibody and CS1-peptide completely abolished cellular infiltration of the islet graft 7 days after transplantation, anti-VCAM-1-treated recipients showed a dense peri-islet infiltrate of activated, alpha4 integrin+, cytotoxic T cells.

CONCLUSIONS

These data show that alpha4 integrin is critically important to allograft rejection. Anti-VCAM-1 antibody appears to prevent rejection without qualitatively affecting either T cell activation or migration to the graft. Conversely, anti-alpha4 integrin antibody and CS1-peptide may prevent islet allograft rejection by altering either T cell activation or lymphocyte trafficking. Blocking interactions between alpha4 integrin and its ligands may provide novel forms of immunosuppression.

Clinical experience with human anodal trypsinogen (HAT) for detection of pancreatic allograft rejection

To date one of the major dilemmas in clinical pancreas transplantation is the lack of a reliable indicator for pancreas rejection. In a consecutive series of 52 patients undergoing simultaneous pancreas and kidney (SPK) transplantation with bladder drainage technique between October 1991 and December 1992 a new test using serial levels of serum human anodal trypsinogen (HAT) was evaluated for its efficacy to detect pancreas rejection. Postoperative baseline levels of HAT were compared to peak HAT values at time of rejection. HAT profiles at time of rejection were calculated and compared to profiles of urinary amylase, serum amylase, fasting blood sugar and serum creatinine. In this series one year patient survival was 97%, graft survival of the pancreas 86% and of the kidney 90%. In 71% of the patients at least one rejection episode occurred. At time of kidney-biopsy proven rejection with a concurrent serum creatinine rise a significant HAT level rise to more than 1000 ng/ml was observed from baseline levels of 200 ng/ml (P < 0.001) indicating kidney and pancreas rejection (73%). Urinary amylase levels decreased in the majority of rejection episodes at the same time from baseline levels to less than 20,000 U/l. In 25% of the rejection episodes a significant serum creatinine rise was observed without a HAT rise or urinary amylase decrease indicating kidney-only rejection, while in 2% a urinary amylase decrease and simultaneous HAT also was observed with a negative kidney biopsy indicating pancreas-only rejection. We feel that increase in HAT levels significantly correlates with pancreas rejection. After SPK, determination of HAT is an additional helpful non-invasive test. In pancreas transplantation alone HAT can be a useful indicator to detect rejection and facilitate timing of a pancreas biopsy and initiation of antirejection treatment.