Protocol biopsies in renal transplantation: insights into patient management and pathogenesis

A 1-day symposium on the application of protocol biopsies in renal transplantation was held in Boston, 21 July 2006. Representatives from centers with extensive experience in the use of protocol biopsies for routine patient care and research reported results on the pathological findings and their value in patient management. The consensus was that protocol biopsies, in experienced hands, are a safe and valuable means of detecting subclinical disease that can benefit from modification of therapy. Furthermore, molecular studies reveal evidence of activity or progression not readily appreciated by histological techniques. Wider application is expected in multicenter clinical trials to predict and validate outcomes. The principal barrier to wider use of protocol biopsies is knowledge of the benefits of intervention.

The effect of desensitization protocols on human splenic B-cell populations in vivo

Rituximab, intravenous immunoglobulin (IVIG) and rabbit antithymocyte globulin (rATG) all have been suggested to have an effect on antibody producing cells, however, supporting data are lacking. To assess the impact of these agents on splenic B-cell populations in vivo, we retrospectively examined 25 spleens removed from patients treated with these agents as part of desensitization protocols in either ABO incompatible or positive crossmatch living donor kidney transplantation. These were compared to control (CTL) spleens removed for trauma. CTLs and spleens removed at transplant after multiple pretransplant plasmaphereses (PP) plus low-dose IVIG showed similar large numbers of naïve B cells (CD20+ and CD79+), plasma cells (CD138+) and memory B cells (CD27+ cells). Adding rituximab to this PP/IVIG regimen reduced the number naïve B cells, but had no effect on memory or plasma cells. Combination treatment (PP/IVIG, rituximab and rATG) showed a trend toward the reduction of CD27+ cells, but again plasma cells were unchanged. We conclude that none of these protocols reduces splenic plasma cells in vivo. PP/low-dose IVIG does not alter splenic B cells, but the addition of rituximab decreases mature B cells. Memory B cells may be affected by combination therapy including rATG and requires further study.

Comparison of Low Versus High Tacrolimus Levels in Kidney Transplantation: Assessment of Efficacy by Protocol Biopsies

BACKGROUND

The use of calcineurin inhibitors is generally guided by drug blood levels. However, those levels are chosen based on clinical experience, lacking adequate titration studies.

METHODS

In these analyses, we compared clinical and histologic endpoints in two groups of kidney transplant recipients: in the first (HiTAC, January 2000 to June 2002, n=245) tacrolimus levels were significantly higher than in the second (LoTAC, July 2002 to September 2004, n=330). This change in drug levels (15% reduction) was made in an attempt to reduce the incidence of polyoma virus nephropathy (PVAN). Other immunosuppressive medications were unchanged during these two time periods.

RESULTS

The recipient and donor demographics were not statistically different between the two groups. Compared to HiTAC, at one year posttransplant LoTAC had: 1) lower incidence of PVAN (10.5% vs. 2.5%, P<0.0001); 2) lower fasting glucose levels; 3) higher iothalamate glomerular filtration rate (52+/-19 vs. 59+/-17 ml/min/m, P<0.0001); and 4) on protocol one-year biopsies, lower incidence and severity of interstitial fibrosis (67% vs. 45%, P=0.003) and tubular atrophy (82% vs., 66%, P=0.01). The incidence and severity of acute rejection episodes was similar between both groups (7.8% versus 7.6%).

CONCLUSIONS

Modest reductions in tacrolimus exposure early posttransplant are associated with significant beneficial effects for the patient and the allograft without an increased immunologic risk.

Preemptive Living Donor Kidney Transplantation: Do the Benefits Extend to All Recipients?

BACKGROUND

Preemptive kidney transplantation (prior to the institution of dialysis) avoids the morbidity and mortality of dialysis; however, detailed studies of high-risk patients are lacking. The aim of the current study was to compare recent outcomes of preemptive (P) versus nonpreemptive (NP) living donor kidney transplantation with an emphasis on high-risk recipients.

METHODS

We retrospectively analyzed 438 sequential solitary living donor kidney transplants at our institution between January 2000 and December 2002. In all, 44% were preemptive. NP recipients were dialyzed for 21+/-36 months (range 1-312 months).

RESULTS

Overall, three-year patient survival was similar in the NP and P groups. When stratified by diabetes and age >65 years, P and NP recipients again showed similar survival. Death-censored three-year graft survival was better in the P group (97% vs. 90%, P=0.01), but was not significant by multivariate analysis. Delayed graft function was more frequent in NP vs. P (10% vs. 4%; P=0.01), but other early complications were similar including: acute rejection, 16% vs. 11% (P=0.11); primary nonfunction, 3% vs. 2% (P=0.38); and wound complications, 19% vs. 17% (P=0.54). Glomerular filtration rate at three years was similar in the two groups (53+/-23 preemptive vs. 52+/-20 ml/min nonpreemptive; P=0.37).

CONCLUSION

With prompt referral and workup, preemptive kidney transplantation can be performed successfully in a large percentage of renal allograft recipients. Preemptive transplantation avoids unnecessary dialysis and should be emphasized as initial therapy for many patients with end-stage renal disease.

Complications, resource utilization, and cost of ABO-incompatible living donor kidney transplantation

BACKGROUND

The transplantation of living donor renal allografts across blood group barriers requires protocols to reduce and maintain anti-blood group antibody at safe levels. These protocols lead to an increase in resource utilization and cost of transplantation and may result in increased complications.

METHODS

In this retrospective study, we compared 40 ABO-incompatible to 77 matching ABO-compatible living donor renal allografts with respect to complications, resource utilization, and cost from day -14 to 90 days after transplantation.

RESULTS

Overall, surgery-related complications and resource utilization were increased in the ABO-incompatible group, primarily due to the desensitization protocol and antibody-mediated rejection. In the absence of rejection, the mean number of complications was similar for both groups. ABO-incompatible kidney transplantation was approximately 38,000 US dollars more expensive than ABO-compatible transplants, but was cost effective when compared to maintaining the patient on dialysis while waiting for a blood group compatible deceased donor kidney. Actuarial graft and patient survival was similar in the two groups.

CONCLUSIONS

We conclude that ABO-incompatible living donor kidney transplantation is a viable option for patients whose only donor is blood group incompatible despite the additional resource utilization and cost of therapy.

Glomerular volume and renal histology in obese and non-obese living kidney donors

The link between obesity and renal disease is unclear, and there is no consensus as to whether obese individuals are at increased risk for kidney disease after living kidney donation if they otherwise meet acceptance criteria. We retrospectively studied time-zero (implantation) biopsies in 49 obese (body mass index (BMI) > or = 30 kg/m2) and 41 non-obese (BMI < 30 kg/m2) renal donors that met acceptance criteria. We found that our obese donor population had higher systolic blood pressure (P < 0.001 vs non-obese) and higher absolute iothalamate clearance (P = 0.001 vs non-obese) before donation. The obese donors had larger glomerular planar surface area compared to non-obese controls (P = 0.017), and this parameter correlated with patient weight and urinary microalbumin excretion. Detailed examination of the biopsies revealed that although most histologic findings were similar between groups, the obese donors had more tubular dilation (P = 0.01), but less tubular vacuolization (P = 0.02) than the non-obese controls. There was also a trend toward more arterial hyalinosis in the obese patients than controls (P = 0.08). From these data, our studies detected subtle differences in donor organs obtained from obese compared to non-obese individuals. Further studies should be carried out to quantify the long-term impact of these findings.

Collapsing and non-collapsing focal segmental glomerulosclerosis in kidney transplants

BACKGROUND

The aetiological and clinical associations of collapsing focal segmental glomerulosclerosis (cFSGS) following kidney transplantation (KTx) are poorly described. In this study, post-transplant cFSGS and non-collapsing FSGS (ncFSGS) were compared in recent KTx recipients. Evidence for intragraft viral infection was sought.

METHODS

Twenty-nine cases of post-KTx FSGS were identified and classified as cFSGS (n = 10) or ncFSGS (n = 19). Biopsies were scored using Banff '97 criteria and subjected to in situ hybridization (ISH) for parvovirus B19 (pvB19), simian virus 40 (SV40) and BK virus (BKV).

RESULTS

cFSGS and ncFSGS patients were comparable for age, gender, weight, delayed function, human leucocyte antigen (HLA) matching, acute rejection and median time to diagnosis. Deceased donor source was more common among cFSGS cases (70 vs 32%, P = 0.05). FSGS was recurrent in 2/10 cFSGS cases compared with 8/19 ncFSGS (P = NS). cFSGS was associated with more proteinuria (11.9 vs 7.2 g/day, P = 0.05) and higher serum creatinine (4.2 vs 1.9 mg/dl, P = 0.0001) at diagnosis. Plasmapheresis was used in two out of 10 cFSGS and seven out of 19 ncFSGS cases with treatment response in 0 of two and three of seven, respectively. Graft loss was more rapid with cFSGS compared with ncFSGS (P = 0.02). Histologically, cFSGS was associated with more severe chronic vascular abnormalities. All biopsies were negative for pvB19, SV40 and BKV by ISH.

CONCLUSIONS

cFSGS following KTx presents with higher proteinuria, diminished renal function, more severe vascular disease and higher rate of graft loss compared with the non-collapsing form. There was no evidence for infection by pvB19 or polyomaviruses.

Histologic findings one year after positive crossmatch or ABO blood group incompatible living donor kidney transplantation

Recent protocols have allowed successful positive crossmatch (+XM) and ABO incompatible (ABOI) kidney transplantation, although their long-term outcome is not clear. To begin to assess this issue we compared protocol biopsies performed 12 months posttransplant in 37 +XM, 24 ABOI and 198 conventional allografts. Although the majority in all three groups had only minimal histologic changes, transplant glomerulopathy (TG) was significantly increased in +XM (22% vs. 13% ABOI vs. 8% conventional, p = 0.015), and correlated with prior humoral rejection (HR) by multivariate analysis (odds ratio 17.5, p < or = 0.0001). Patients with a prior history of HR also had a significant increase in interstitial fibrosis (No HR 54% vs. HR 86%, p = 0.045). In the absence of HR no difference in histologic changes was seen between groups, although all three groups had a demonstrable mild increase in interstitial fibrosis from biopsies performed at the time of transplant. Thus, although HR is associated with an increase in TG, in its absence allograft histology is similar in +XM, ABOI and conventional allografts 1 year posttransplant.

Interpreting post-transplant proteinuria in patients with proteinuria pre-transplant

Increasing numbers of patients receive kidney transplants before initiation of dialysis or shortly thereafter. Some of these patients have significant proteinuria pre-transplant making the interpretation of post-transplant proteinuria problematic. In this study, we evaluated post-transplant proteinuria in 115 patients who had urine protein measured within 3 months of transplant and assessed the association of proteinuria with allograft pathology. Proteinuria declined rapidly from 3650 +/- 3702 mg/day pre-transplant to 550 + 918 at 3 weeks (p < 0.0001) and continued to decline until 1 year post-transplant (472 +/- 1116, p < 0.0001 vs. 3 weeks). Proteinuria greater than 3000 mg/day was present in 48 patients (42%) pre-transplant, in 1 patient (1%) at 3 weeks and in 4 patients (4%) at 1 year. Surveillance graft biopsies were done at 1 year in 93% of patients. Proteinuria > or = 1500 mg/day and/or an absolute increase in proteinuria > 500 mg/day after 3 weeks post-transplant was associated with allograft glomerular pathology. In conclusion, pre-transplant proteinuria, even when high grade, declines rapidly after transplantation. Failure to decline or persistence of proteinuria greater than 1500 mg/day is indicative of allograft pathology.

Complete avoidance of calcineurin inhibitors in renal transplantation: a randomized trial comparing sirolimus and tacrolimus

Calcineurin inhibitors have decreased acute rejection and improved early renal allograft survival, but their use has been implicated in the development of chronic nephrotoxicity. We performed a prospective, randomized trial in kidney transplantation comparing sirolimus-MMF-prednisone to tacrolimus-MMF-prednisone. Eighty-one patients in the sirolimus group and 84 patients in the tacrolimus group were enrolled (mean follow-up = 33 months; range 13-47 months). At 1 year, patient survival was similar in the groups (98% with sirolimus, 96% with tacrolimus; p = 0.42) as was graft survival (94% sirolimus vs. 92% tacrolimus, p = 0.95). The incidence of clinical acute rejection was 10% in the tacrolimus group and 13% in the sirolimus group (p = 0.58). There was no difference in mean GFR measured by iothalamate clearance between the tacrolimus and sirolimus groups at 1 year (61 +/- 19 mL/min vs. 63 +/- 18 mL/min, p = 0.57) or 2 years (61 +/- 17 mL/min vs. 61 +/- 19 mL/min, p = 0.84). At 1 year, chronicity using the Banff schema showed no difference in interstitial, tubular or glomerular changes, but fewer chronic vascular changes in the sirolimus group. This study shows that a CNI-free regimen using sirolimus-MMF-prednisone produces similar acute rejection rates, graft survival and renal function 1-2 years after transplantation compared to tacrolimus-MMF-prednisone.

Kidney transplant function and histological clearance of virus following diagnosis of polyomavirus-associated nephropathy (PVAN)

Polyomavirus-associated nephropathy (PVAN) is managed by reduced immunosuppression with or without antiviral therapy. Data from 55 patients with biopsy-proven PVAN were analyzed for adverse outcomes and influence of baseline variables and interventions. During 20+/-11 months follow-up, the frequencies of graft loss, major and any functional decline were 15%, 24% and 38%, respectively. Repeat biopsies were performed in 45 patients with persistent PVAN in 47%. Low-dose cidofovir, IVIG and cyclosporine conversion were used in 55%, 20% and 55% of patients. No single intervention was associated with improved outcome. Of the variables examined, only degree of interstitial fibrosis at diagnosis was associated with kidney function decline. In contrast, donor source, interstitial fibrosis, proportion of BKV positive tubules and plasma viral load at diagnosis were all associated with failure of histological viral clearance. This retrospective, nonrandomized analysis suggests that: (i) Graft loss within 2 years of PVAN diagnosis is now uncommon, but ongoing functional decline and persistent infection occur frequently. (ii) Low-dose cidofovir, IVIG and conversion to cyclosporine do not abrogate adverse outcomes following diagnosis. (iii) Fibrosis at the time of diagnosis predicts subsequent functional decline. Further elucidation of the natural history of PVAN and its response to individual interventions will require prospective clinical trials.

Complete avoidance of calcineurin inhibitors in renal transplantation: a randomized trial comparing sirolimus and tacrolimus

Calcineurin inhibitors have decreased acute rejection and improved early renal allograft survival, but their use has been implicated in the development of chronic nephrotoxicity. We performed a prospective, randomized trial in kidney transplantation comparing sirolimus-MMF-prednisone to tacrolimus-MMF-prednisone. Eighty-one patients in the sirolimus group and 84 patients in the tacrolimus group were enrolled (mean follow-up = 33 months; range 13-47 months). At 1 year, patient survival was similar in the groups (98% with sirolimus, 96% with tacrolimus; p = 0.42) as was graft survival (94% sirolimus vs. 92% tacrolimus, p = 0.95). The incidence of clinical acute rejection was 10% in the tacrolimus group and 13% in the sirolimus group (p = 0.58). There was no difference in mean GFR measured by iothalamate clearance between the tacrolimus and sirolimus groups at 1 year (61 +/- 19 mL/min vs. 63 +/- 18 mL/min, p = 0.57) or 2 years (61 +/- 17 mL/min vs. 61 +/- 19 mL/min, p = 0.84). At 1 year, chronicity using the Banff schema showed no difference in interstitial, tubular or glomerular changes, but fewer chronic vascular changes in the sirolimus group. This study shows that a CNI-free regimen using sirolimus-MMF-prednisone produces similar acute rejection rates, graft survival and renal function 1-2 years after transplantation compared to tacrolimus-MMF-prednisone.

A comparison of plasmapheresis versus high-dose IVIG desensitization in renal allograft recipients with high levels of donor specific alloantibody

Several protocols allow for the successful transplantation of sensitized renal allograft recipients, yet no one best method has emerged. The aim of the current study was to compare the efficacy of high-dose IVIG with two different plasmapheresis (PP)-based regimens in kidney transplant recipients with high levels of donor specific alloantibody (DSA) defined as a positive T-cell cytotoxicity crossmatch. With the primary goal of achieving a negative crossmatch, we employed three protocols sequentially between April 2000 and May 2005: (i) PP, low-dose IVIG, anti-CD20 antibody (n = 32); (ii) high-dose IVIG (n = 13); and (iii) PP, low-dose IVIG, anti-CD20 antibody and pre-transplant Thymoglobulin combined with post-transplant DSA monitoring (n = 16). IVIG decreased DSA activity in all treated patient, yet only 38% (5/13) achieved a negative crossmatch. In contrast, a negative crossmatch was achieved in 84% in PP group and 88% in the PP/monitoring group (p < 0.01 vs. IVIG). Even with a negative crossmatch, the rejection rates were 80% (IVIG), 37% (PP) and 29% (PP/monitoring), respectively, (p < 0.05 IVIG vs. PP). We conclude that multiple PP treatments leads to more reproducible desensitization and lower humoral rejection rates than a single high-dose of IVIG, but that no regimen was completely effective in preventing humoral rejection.

A Comparison of splenectomy versus intensive posttransplant antidonor blood group antibody monitoring without splenectomy in ABO-incompatible kidney transplantation

BACKGROUND

Although most protocols for ABO-incompatible kidney transplantation have employed splenectomy, its utility is unproven. The aim of the current study was to compare the outcomes of ABO-incompatible living donor kidney transplantation with splenectomy versus a protocol involving intensive posttransplant antibody monitoring to maintain low levels of antiblood group antibody.

METHODS

We retrospectively studied all ABO-incompatible living donor kidney transplants at our institution between September 1999 and November 2004 (n=34). Prior to May 2003, all patients were included in a protocol involving pretransplant plasmapheresis and splenectomy at the time of transplant (n=23). After May 2003, splenectomy was not performed and a protocol that involved pretransplant anti-CD20 antibody and a more intensive posttransplant plasmapheresis regiment aimed at maintaining low levels of antiblood group antibody during the first 2 weeks following transplantation was utilized (n=11).

RESULTS

Patient and graft survival was similar in the two groups. Humoral rejection occurred in 18% nonsplenectomized and 30% of splenectomized patients (P=0.68). Humoral rejection correlated with the baseline antibody titer in both groups. Individuals with elevated baseline antibody titer (> or =1:256) appear to be at high risk for humoral rejection regardless of protocol used. Antiblood group antibody levels 3 and 12 months after transplantation were similar in both groups.

CONCLUSIONS

Splenectomy is not essential for successful ABO-incompatible kidney transplantation, although individuals with high baseline antidonor blood group antibody titers are at high risk for humoral rejection. The use of intensive posttransplant monitoring may help prevent antibody-mediated graft damage.

Improving the prediction of donor kidney quality: deceased donor score and resistive indices

BACKGROUND

The deceased donor score (DDS), expanded criteria donor (ECD) definition, and resistive index (RI) were developed for pretransplant evaluation of donors. DDS and ECD are determined by a calculation of risk from donor variables, while RI is determined from flow characteristics of kidneys during machine preservation (MP). This study was designed to compare DDS, ECD status, and RI as predictors of outcome after deceased donor transplantation. We were also interested to see if DDS or ECD could identify kidneys most likely to benefit from MP.

METHODS

We retrospectively reviewed 48,952 deceased donor renal transplants reported to UNOS from 1997-2002. DDS (0-39 pts.), ECD status (+ or -), and preservation technique (MP vs. cold storage [CS]) were determined in all cases. RI during MP was studied in a single-center cohort of 425 transplants.

RESULTS

DDS was superior to ECD status and RI in its correlation with early and late renal function after transplantation. DDS identified a subgroup of ECD- kidneys, those with DDS > or = 20 pts, that functioned significantly below expectation and similar to ECD+ kidneys. Benefits of MP, which include improved early graft function and a trend towards longer graft survival, were greatest in the group of kidneys with DDS > or = 20 pts.

CONCLUSIONS

DDS was the best predictor of outcome after deceased donor renal transplantation and may be useful in identifying kidneys most likely to benefit from MP.

Predicting subsequent decline in kidney allograft function from early surveillance biopsies

Identifying factors that are predictive of allograft loss might be an important step toward prolonging kidney allograft survival. In this study we sought to determine the association between histologic changes on 1-year surveillance biopsies, changes in graft function and survival. This analysis included 292 adults, recipients of kidneys from living donors (69%) or deceased donors (31%), transplanted between 1998 and 2001 and followed up for 46 +/- 14 months. The primary end point was death-censored graft loss or a >50% reduction in GFR beyond 1 year. One-year biopsies were classified as: (i) Normal (N = 87, 30%), (ii) inflammation (N = 6, 2%), (iii) fibrosis (N = 131, 45%), (iv) fibrosis and inflammation (N = 53, 18%) and (v) transplant glomerulopathy (N = 15, 5%). By multivariate Cox analysis, survival related to biopsy classification (HR = 4.2, p = 0.001), graft function (HR = 0.97, p = 0.001) and HLA mismatches (HR = 1.003, p = 0.004). Using normal histology as a reference, fibrosis and inflammation (HR = 8.5, p < 0.0001) and glomerulopathy (HR = 10, p < 0.0001) related to poorer survival but mild fibrosis alone did not. Importantly, the degree of inflammation associated with fibrosis generally did not qualify for the diagnosis of borderline rejection. In conclusion, inflammation and glomerulopathy 1 year post-transplant predict loss of graft function and graft failure independently of function and other variables.

Predicting subsequent decline in kidney allograft function from early surveillance biopsies

Identifying factors that are predictive of allograft loss might be an important step toward prolonging kidney allograft survival. In this study we sought to determine the association between histologic changes on 1-year surveillance biopsies, changes in graft function and survival. This analysis included 292 adults, recipients of kidneys from living donors (69%) or deceased donors (31%), transplanted between 1998 and 2001 and followed up for 46 +/- 14 months. The primary end point was death-censored graft loss or a >50% reduction in GFR beyond 1 year. One-year biopsies were classified as: (i) Normal (N = 87, 30%), (ii) inflammation (N = 6, 2%), (iii) fibrosis (N = 131, 45%), (iv) fibrosis and inflammation (N = 53, 18%) and (v) transplant glomerulopathy (N = 15, 5%). By multivariate Cox analysis, survival related to biopsy classification (HR = 4.2, p = 0.001), graft function (HR = 0.97, p = 0.001) and HLA mismatches (HR = 1.003, p = 0.004). Using normal histology as a reference, fibrosis and inflammation (HR = 8.5, p < 0.0001) and glomerulopathy (HR = 10, p < 0.0001) related to poorer survival but mild fibrosis alone did not. Importantly, the degree of inflammation associated with fibrosis generally did not qualify for the diagnosis of borderline rejection. In conclusion, inflammation and glomerulopathy 1 year post-transplant predict loss of graft function and graft failure independently of function and other variables.

Prognostic analysis for survival in adult solid organ transplant recipients with post-transplantation lymphoproliferative disorders

PURPOSE

The objective of this study was to determine prognostic factors for overall survival in patients with post-transplantation lymphoproliferative disorders (PTLDs).

PATIENTS AND METHODS

This study focused on the 107 adult solid organ transplantation patients who were diagnosed with PTLDs at Mayo Clinic (Rochester, MN) between December 1970 and May 2003.

RESULTS

The median age at the time of diagnosis was 48 years (range, 15 to 75 years). Extranodal disease including grafted organ involvement was present in 85 patients (80%). The graft organ was involved in 30 patients (28%). At the time of these analyses, 62 patients (58%) had died. The median survival for the entire cohort was 31.5 months (95% CI, 10.7 to 72.5 months). The median follow-up of living patients was 51.8 months (range, 5.6 to 202.6 months). In univariate analyses for overall survival from the time of PTLD diagnosis, the following poor prognostic factors were identified: poor performance status with Eastern Cooperative Oncology Group levels 3 and 4 (P < .0001), grafted organ involvement (P = .0005), the presence of one or more extranodal sites (P = .005), both nodal and extranodal disease (P = .002), high International Prognostic Index (P = .006), advanced stage (P = .001), and elevated lactate dehydrogenase (P = .03). A final multivariable model for survival was constructed using three factors: poor performance status (3 to 4), monomorphic disease, and graft organ involvement.

CONCLUSION

A prognostic model has been developed for PTLD patients using one center's 30 years of experience. We propose additional confirmation and validation of these prognostic factors in larger prospective studies.

New onset hyperglycemia and diabetes are associated with increased cardiovascular risk after kidney transplantation

BACKGROUND

Post-transplant diabetes (PTDM) is a common and serious complication of kidney transplantation. The implications of developing hyperglycemia of lesser severity are not well understood.

METHODS

In this study we used American Diabetes Association (ADA) criteria to assess the incidence of abnormal glycemia post-transplant, the variables that relate to this complication, and the relationship between hyperglycemia and cardiovascular (CV) disease. Included in the study were 490 kidney recipients, transplanted from 1998 to 2003, without a history of diabetes, and with a pretransplant fasting glucose <126 mg/dL.

RESULTS

Within one week post-transplant, 45% of recipients had impaired fasting glycemia (IFG, glucose 100-125 mg/dL), and 21% PTDM (glucose > or =126). One year post-transplant, 33% of patients had IFG, and 13% PTDM. Risk factors for hyperglycemia at one year included: older recipient, male gender, higher BMI, higher pretransplant glucose, and higher glucose one week post-transplant (all P < 0.002 by multivariable analyses). During a follow-up period of 40 +/- 14 months, 12% of recipients had CV events (cardiac, CVA, and/or peripheral). Increasing fasting glucose levels at one, four, and/or 12 months post-transplant were significantly related to CV events. Furthermore, these relationships were independent of other CV risk factors, including: older age, CV events pretransplant, male gender, dyslipidemia, and transplant year. Fasting glucose levels >100 mg/dL were associated with higher incidence of post-transplant cardiac (P= 0.001) and peripheral vascular disease events (P= 0.003).

CONCLUSION

The incidence of post-transplant hyperglycemia and its CV impact have been underestimated. Pretransplant characteristics and, particularly, the glycemia during the first month post-transplant identified patients at risk of PTDM. Increasing glucose levels greater than 100 mg/dL, any time after the first month post-transplant, are associated with increasing CV risk. We postulate that aggressive detection and treatment of post-transplant hyperglycemia may significantly reduce CV morbidity and mortality after kidney transplantation.

Outcome of untreated grade II rejection on solitary pancreas allograft biopsy specimens

BACKGROUND

The most widely used grading scheme for acute pancreas allograft rejection grades biopsy specimens from 0 (normal) to V (severe rejection). Although the more advanced grades correlate strongly with immunologic graft loss, it is unclear how lesser grades impact graft outcome. The authors therefore report the outcomes of untreated grade II (minimal) rejection of solitary pancreas biopsy specimens.

METHODS

The authors retrospectively analyzed all solitary pancreas transplants performed at the Mayo Clinic between January 2001 and November 2002. The authors selected all patients who were found with grade II findings on biopsy. Whether patients underwent follow-up biopsies, what the results were, and graft survival at the end of the study period were then determined.

RESULTS

A total of 88 pancreas transplants were performed; 20 pancreas transplant recipients (23%) developed grade II (minimal) rejection and were followed for a mean of 22.8+/-8.7 months. Eighteen patients underwent biopsy for protocol purposes and two patients underwent clinically indicated biopsies. Of the patients who underwent biopsy as per protocol, 15 of the patients had a total of 25 follow-up biopsies: 10 were grade 0; 3 were grade I; and 10 were unchanged (grade II). Rejection in one patient progressed to grade III and in another patient to grade IV. The three patients who did not undergo repeat biopsy had a functioning allograft pancreas at the end of the study period. Of the two patients with grade II biopsy specimens obtained for clinical reasons, one had resolution of all inflammation noted on three follow-up biopsies, and the other patient did not undergo follow-up biopsy and died with a functioning graft.

CONCLUSIONS

Grade II (minimal) rejection of solitary pancreas allograft rarely progresses to more severe degrees of inflammation. Morphologic findings in this category may not have unfavorable prognoses over a period of 2 years when untreated.

A novel model of allograft rejection: immune reconstitution of Rag-1 recipients with 2C transgenic T-cell receptor lymphocytes

The complexity of allorejection (cell activation, homing, and effector function) makes detailed studies difficult. We have developed a model of allograft rejection using purified monoclonal alloreactive effector cells. Immunodeficient C57Bl/6-Rag-1 (H-2(b)) recipients of Balb/c (H-2(d)) islet or skin grafts were reconstituted via adoptive transfer of splenocytes from 2C transgenic mice containing CD8+ cytotoxic effector cells directed against L(d). Recipients were assessed for engraftment, activation and homing of effector cells, and ability to reject grafts. Both unpurified 2C splenocytes and purified 2C/CD8+ cells durably reconstitute immunodeficient mice. Naive 2C effector cells reject skin grafts, but not islet allografts. However, when effector cells are primed prior to reconstitution, islet allografts are rejected. Using this model, blockade of adhesion molecules LFA-1 and alpha4-integrin delayed infiltration of islet allografts and prolonged allograft survival. This model of allorejection may be useful to study the activation and homing of allospecific cells in vivo.

Living donor kidney and autologous stem cell transplantation for primary systemic amyloidosis (AL) with predominant renal involvement

Primary systemic amyloidosis (AL) is characterized by multiorgan deposition of monoclonal immunoglobulin light chain. Renal involvement is common and impaired kidney function is associated with reduced median survival. Autologous stem cell transplantation (SCT) for AL achieves superior response rates compared to chemotherapy alone but patients with end-stage renal disease (ESRD) may be excluded from consideration. A treatment approach consisting of living donor kidney transplantation (LDKTx) followed by autologous SCT was developed for AL with ESRD. Eight patients underwent LDKTx with immediate graft function. Two suffered unanticipated complications post-KTx and died 10 and 3 months later. Two cases of subclinical acute cellular rejection (ACR) and one case of clinical ACR occurred--all reversible with corticosteroid. Six patients had successful stem cell harvests performed and five of these underwent SCT with satisfactory trilineage engraftment. Renal function remained stable following SCT in four and was reduced in one due to infectious and bleeding complications. One patient, who has thus far elected not to undergo SCT, has proteinuria and histologic evidence of recurrent renal amyloidosis. This experience supports the feasibility of sequential living donor KTx and autologous SCT for carefully selected patients with ESRD due to AL.

Early subclinical coronary artery calcification in young adults who were pediatric kidney transplant recipients

Coronary artery disease (CAD) is the leading cause of death in adults after successful kidney transplantation. Children who have undergone successful kidney transplantation are entering young adulthood; however, the prevalence and extent of CAD in this population is unknown. We conducted a pilot study in young adults with stable allograft function, who received kidney transplants as children to measure coronary artery calcification (CAC), a marker of coronary artery atherosclerosis and CAD. We evaluated 19 young adults after successful pediatric kidney transplantation for known CAD risk factors; these patients underwent noninvasive imaging with electron-beam computed tomography (EBCT) for measurement of CAC. Prevalence and quantity of CAC were then compared to asymptomatic individuals from the community. All patients had multiple risk factors for CAD. Mean age at evaluation was 32 years (range: 21-48 years). CAC is uncommon in individuals in the community in this age range; however, nearly half of our patients had CAC detected with the quantity of CAC comparable to asymptomatic individuals from the community 10-40 years older. These data suggest young adults who received pediatric kidney transplants are at increased risk for developing early CAC and need close monitoring to detect early CAD so as to prevent premature cardiac morbidity and mortality.

United Network for Organ Sharing's expanded criteria donors: is stratification useful?*

The United Network for Organ Sharing (UNOS) Expanded Criteria Donor (ECD) system utilizes pre-transplant variables to identify deceased donor kidneys with an increased risk of graft loss. The aim of this study was to compare the ECD system with a quantitative approach, the deceased donor score (DDS), in predicting outcome after kidney transplantation. We retrospectively reviewed 49 111 deceased donor renal transplants from the UNOS database between 1984 and 2002. DDS: 0-39 points; >or=20 points defined as marginal. Recipient outcome variables were analyzed by ANOVA or Kaplan-Meier method. There was a 90% agreement between the DDS and ECD systems as predictors of renal function and graft survival. However, DDS identified ECD- kidneys (10.7%) with a significantly poorer outcome than expected (DDS 20-29 points, n = 5,252). Stratification of ECD+ kidneys identified a group with the poorest outcome (DDS >or=30 points). Predictability of early post-transplant events (i.e. need for hemodialysis, decline of serum creatinine and length of hospital stay) was also improved by DDS. DDS predicted outcome of deceased donor renal transplantation better than the ECD system. Knowledge obtained by stratification of deceased donor kidneys can allow for improved utilization of marginal kidneys which is not achieved by the UNOS ECD definition alone.