Immunomodulation through inhibition of multiple adhesion molecules generates resistance to autoimmune diabetes in NOD mice

The effect of simultaneous blockade of adhesion molecules on the development of long-term resistance to type 1 diabetes was investigated in an adoptive transfer model in NOD mice. Splenocytes isolated from acutely diabetic NOD mice injected into NOD-scid mice caused diabetes at 43 +/- 5.0 days. Treatment with anti-alpha4-integrin monoclonal antibody (mAb) delayed the onset of insulitis and significantly delayed hyperglycemia to 66 +/- 5.8 days. Combination treatment with anti-alpha4-integrin and anti-LFA-1 mAbs delayed the onset of diabetes to >100 days (p<0.0001). Combination-treated mice were subjected to a second challenge with diabetogenic splenocytes after 85 days of normoglycemia. Without additional mAb treatment they developed hyperglycemia after significant delay (72 +/- 8.1 days post-reinoculation). Splenocytes from combination-treated mice transferred protection from diabetes to naive NOD-scid mice when co-transferred with diabetogenic splenocytes. The long-surviving mice showed periislet infiltration with CD62L+ cells, which were not seen in the insulitis developing in control animals. These findings suggest that adhesion molecule blockade does not prevent homing and may affect effector cell action through activation of immunoregulatory suppressor cells, leading to protection against development of diabetes.

Obesity in living kidney donors: clinical characteristics and outcomes in the era of laparoscopic donor nephrectomy

Acceptance of obese individuals as living kidney donors is controversial related to possible increased risk for surgical complications and concern that obesity may contribute to long-term renal disease. We retrospectively examined 553 consecutive hand-assisted laparoscopic living kidney donations between October 1, 1999 and April 1, 2003. We stratified donors into quartiles by baseline body mass index (BMI) assessing perioperative complications and 6-12 months post-donation metabolic and renal function. Compared to BMI <25 kg/m(2), high BMI donors (> or =35 kg/m(2)) had slightly longer operative times (mean increase 19 min), more overall perioperative complications (mostly minor wound complications), yet the same low rate of major surgical complications (conversion to open and re-operation) and similar length-of-stay (2.3 vs. 2.4 days). At 6-12 months after donation (mean 11 months), renal function and microalbuminuria did not differ with BMI. These results suggest that laparoscopic donor nephrectomy is generally safe in selected obese donors and does not result in a high rate of major perioperative complications. Obese donors have higher baseline cardiovascular risk and warrant risk reduction for long-term health. While early results are encouraging, we advocate careful study of obese donors and do not support their widespread use until longer follow-up is available.

Kidney allograft fibrosis and atrophy early after living donor transplantation

Kidney allograft failure is most often caused by chronic allograft nephropathy, a process of interstitial fibrosis (GIF) and tubular atrophy (TA). We assessed the pathology of living donor (LD) grafts compared to deceased donor (DD). Included are 321 recipients (245 LD; 76 DD) with protocol biopsies the first 2 years of transplant. In LD, GIF was present in 7%, 31%, 61% and 71% of grafts at 0, 4, 12 and 24 months. TA progressed in parallel to GIF. Compared to LD, more DD grafts had GIF at time 0 (29%, p = 0.002); thereafter the incidence of GIF was similar. In LD, GIF was associated with lower glomerular filtration rate (GFR)(1 year) (no GIF, 62 +/- 16; GIF, 49 +/- 15 mL/min/m(2) iothalamate clearance, p = 0.001) and reduced graft survival (HR = 2.2, p = 0.009). GIF in LD related to acute rejection (HR = 2.6, p = 0.01), polyoma nephropathy (OR = 4.4, p = 0.02) and lower levels of GFR 3 weeks post-transplant (HR = 0.961; p = 0.03, multivariate). However, GIF also developed in 53% of recipients lacking these covariates. Thus, GIF/TA develops in the majority of LD grafts, it is often mild but is associated with reduced function and survival. GIF frequently develops in the absence of risk factors. Lower GFR post-transplant identify patients at highest risk of GIF.

Differences between early and late posttransplant lymphoproliferative disorders in solid organ transplant patients: are they two different diseases?

BACKGROUND

The objective of the authors' study was to characterize the clinical and pathologic differences between patients who develop posttransplant lymphoproliferative disorders (PTLD) early or late after transplantation and to assess the overall survival in these two groups.

METHODS

One hundred seven adult solid organ transplant patients were identified at the Mayo Clinic between December 1970 and May 2003.

RESULTS

Forty-nine patients developed PTLD within the first year (early PTLD, 1-11.8 months) and 58 patients developed PTLD after 1 year (late PTLD, 14 months-17 years). Patients with early PTLD more commonly had the following characteristics: positive Epstein-Barr virus (EBV) in situ hybridization status (P < 0.0001), CD20-positive status (P = 0.002), and involvement of the grafted organ (P = 0.02). Overall survival did not differ between the two groups (P = 0.25). PTLD may occur in two different settings with different characteristics.

CONCLUSIONS

Early PTLD is more commonly EBV in situ hybridization-positive and CD20-positive, and more commonly involves the grafted organ.

ABO-incompatible kidney transplantation

When a renal transplant candidate's only medically-acceptable living kidney donor is ABO incompatible, the most common practice is to place them on the deceased donor list. Over the past few years, the implementation of paired kidney donor exchange programs and the development of protocols to overcome the ABO blood group barrier have become much more successful and widespread. Here we review the therapeutic options for patients whose only living kidney donor is ABO incompatible, with a specific emphasis on the rationale for and the current outcomes of ABO incompatible living donor kidney transplantation.

Hand-assisted laparoscopic donor nephrectomy for pediatric kidney allograft recipients

Laparoscopic donor nephrectomy (LDN) is the method of choice for procuring kidneys from living donors at many transplant centers. The aim of this study was to assess the feasibility as well as outcome of LDN in pediatric recipients. Twenty-two pediatric patients, 18-yr old or younger received kidneys procured by a hand-assisted LDN technique. The mean operative time was no different (p = 0.9) and the mean length of stay was more than 1 day shorter in the LDN group (p = 0.0001) compared with the 13 pediatric patients who received kidneys by standard open nephrectomy. Body mass index (BMI), number of donor kidney vessels, or laterality of the kidney did not impact the donor operation or outcome. Actuarial 1-yr patient survival was 100% and allograft survival was 95%, which are equivalent to registry data. There were no donor mortalities and there were five morbidities. None required hospitalization. There were no conversions from LDN to open nephrectomy. One kidney was lost because of overwhelming infection necessitating withdrawal of immunosuppression. In conclusion, hand-assisted LDN is a safe method of procuring kidneys from potential donors with no significant negative outcomes to the pediatric recipients.

Patient and graft outcomes from older living kidney donors are similar to those from younger donors despite lower GFR

BACKGROUND

Donor age adversely affects deceased-donor kidney transplant outcomes, but its influence on living-donor transplantation is less well characterized.

METHODS

Living-donor kidney transplants at a single center between 1998 and 2000 were reviewed. Data were abstracted for 52 transplants from donors aged > or =50 years and for a matched group of 104 transplants from donors aged <50 years. Survival indices were compared during the first three years' post-transplantation. Functional indices, including serial iothalamate clearances, were compared at 1, 12, and 24 months.

RESULTS

Predonation glomerular filtration rate (GFR) was lower among older donors (94 +/- 12 vs. 108 +/- 17 mL/min/SA) but post-transplant compensatory hypertrophy was similar (11.7 +/- 26.3% vs. 7.7 +/- 31.4%). Recipients of older-donor grafts were older (52.8 +/- 16.5 vs. 46.1 +/- 15.1 years) and more frequently unrelated to the donor (54% vs. 39%). Trends toward higher frequency of slow graft function, cytomegalovirus (CMV) infection, and polyomavirus nephropathy were observed for older-donor grafts. Three-year recipient, graft, and death-censored graft survivals were > or =90% for both groups. At 1, 12, and 24 months, serum creatinine was higher and GFR was lower among recipients of older- compared with younger-donor grafts. Other functional indices (urine total protein, serum potassium and uric acid, hemoglobin, and number of antihypertensives) were not different. Donor age correlated with graft GFR at 1, 12, and 24 months for the entire study cohort by linear regression.

CONCLUSION

Older donor age does not preclude excellent results from living-donor kidney transplantation but should be appreciated as being associated with relatively lower GFR.

Acute Nephrotoxicity of Tacrolimus and Sirolimus in Renal Isografts: Differential Intragraft Expression of Transforming Growth Factor-??1 and ??-Smooth Muscle Actin

BACKGROUND

Renal dysfunction early after kidney transplantation has multiple causes including ischemia-reperfusion (I/R) injury and drug-induced nephrotoxicity. This study assesses the acute nephrotoxicity of tacrolimus (Tac) and sirolimus (Sir) in a rat renal isograft model.

METHODS

Lewis renal isografts and uninephrectomized rats that did not undergo transplantation were treated with various doses of Tac (0.5-5.0 mg/kg/d) or Sir (0.5-6.5 mg/kg/d). Kidneys were examined on day 14 by routine histology and immunohistochemistry for transforming growth factor (TGF)-beta1 and alpha-smooth muscle actin (SMA).

RESULTS

Both Tac and Sir demonstrated evidence of nephrotoxicity in the early posttransplant period including increased serum creatinine and morphologic changes in the graft including interstitial inflammation, fibrosis, and tubular vacuolization. Nephrotoxicity was most prominent in the high-dose treatment groups for both drugs and was more severe in transplanted kidneys than in uninephrectomized animals that did not undergo transplantation, suggesting an additive effect of I/R injury and drug nephrotoxicity. Both Tac and Sir increased intragraft TGF-beta1 and alpha-SMA, but there were distinct differences in the patterns of TGF-beta1 expression. Both demonstrated TGF-beta1 in tubular epithelial cells, but Sir was associated with proximal tubular TGF-beta1 localization in a bright granular pattern, whereas Tac was associated with diffuse distal tubular staining.

CONCLUSIONS

Both Tac and Sir may be nephrotoxic in the early posttransplant period, especially at high doses and when combined with I/R injury. Immunohistochemical localization of TGF-beta1 in the tubular cells was distinctly different with each drug, suggesting possible differences in the mechanism(s) of nephrotoxicity requiring further study.

Persistence of Low Levels of Alloantibody after Desensitization in Crossmatch-Positive Living-Donor Kidney Transplantation

BACKGROUND

: Desensitization protocols have been developed to allow successful kidney transplantation in sensitized recipients. However, a detailed analysis of the impact of these protocols on alloantibody has not been performed.

METHODS

: We studied 12 living-donor kidney-transplant recipients with positive antihuman globulin-enhanced complement dependent cytotoxicity (AHG-CDC) crossmatches against their donors. Using a variety of crossmatch techniques and single-antigen flowbeads (SAFBs), we characterized the specificity and amount of alloantibody at baseline before desensitization, after desensitization (using plasmapheresis followed by 100 mg/kg intravenous immunoglobulin, and anti-CD20 antibody), and 4 months after transplantation (after splenectomy and on maintenance immunosuppression).

RESULTS

: All 12 patients with a positive baseline AHG-CDC crossmatch were AHG-CDC crossmatch negative at the time of transplant (after desensitization). However, despite desensitization, the majority of patients had low-level donor-specific alloantibodies demonstrable on the day of transplantation by both flow crossmatch (FXM 8/12) and SAFBs (10/11). Four months after transplantation, no patient had a positive AHG-CDC crossmatch, but again the majority had persistent low levels of donor-specific alloantibodies by FXM (6/12) and SAFBs (9/11). No patient experienced hyperacute rejection, and the persistence of low levels of donor-specific alloantibodies did not correlate with the development of humoral rejection in the early posttransplant period.

CONCLUSIONS

: Despite desensitization, a majority of positive crossmatch transplant recipients demonstrate low levels of donor-specific alloantibodies both on the day of transplant and 4 months after transplantation. The impact of these antibodies appears to be minimal early after transplant, but their long-term significance bears further study.

Wound-healing complications after kidney transplantation: a prospective, randomized comparison of sirolimus and tacrolimus

BACKGROUND

Sirolimus has been associated with an increased risk of wound-healing complications in several retrospective analyses. The authors compared the rates of wound-healing complications in renal allograft recipients in a prospective, randomized trial of sirolimus-mycophenolate mofetil-prednisone versus tacrolimus-mycophenolate mofetil-prednisone.

METHODS

All patients received antithymocyte globulin induction. In the first phase of the study, patients (n = 77) were included regardless of body mass index (BMI). In the second phase (n = 46 patients), the authors excluded patients with a BMI greater than 32 kg/m2, and the target trough sirolimus level was lowered to 10 to 15 ng/mL (previously 15-20 ng/mL). Multivariate logistic regression analyses were performed to identify predictors of wound complications.

RESULTS

Fifty-nine patients received tacrolimus and 64 received sirolimus and were included in subsequent analyses. The incidence of complications was 8% (5 of 59) in the tacrolimus group and 47% (30 of 64) in the sirolimus group (P < 0.0001). Rates of perigraft fluid collections, superficial wound infections, and incisional herniae were significantly higher in the sirolimus group. Multivariate logistic regression showed only sirolimus (P = 0.0001) and BMI (P = 0.0021) to independently correlate with complications. In the first phase of the study, the wound complication rate in the sirolimus group was 55% (21 of 38 patients). After excluding obese recipients and decreasing the target sirolimus level, the wound complication rate in the sirolimus group was 35% (9 of 26 patients; P = 0.1040).

CONCLUSIONS

The use of sirolimus-based immunosuppressive regimens leads to a higher incidence of wound-healing complications and will require new approaches to patient selection and management to decrease their incidence.

Prospective, randomized trial of the effect of antibody induction in simultaneous pancreas and kidney transplantation: three-year results

BACKGROUND

Historically, antibody induction has been used because of the higher immunologic risk of graft loss or rejection observed in simultaneous pancreas and kidney (SPK) transplantation compared with kidney transplantation alone. This trial was designed to assess the effect of antibody induction in SPK transplant recipients receiving tacrolimus, mycophenolate mofetil, and corticosteroids. Induction agents included T-cell-depleting and interleukin-2 receptor antibodies.

METHODS

A total of 174 SPK transplant recipients were enrolled in a prospective, open-label, multi-center study. They were randomized to induction (n=87) or non-induction (n=87) groups and followed for 3 years.

RESULTS

At 3 years, actual patient (94.3% and 89.7%) and pancreas (75.9% and 75.9%) survivals were similar between the induction and non-induction groups, respectively. Actual kidney survival was similar at 1 and 2 years, but at 3 years, it was significantly better in the induction group compared with the non-induction group (92% vs. 81.6%; P =0.04). At 3 years, median serum creatinine and hemoglobin A1C were similar between the induction and non-induction groups (1.35 mg/dL and 1.20 mg/dL, 5.4% and 5.5%, respectively). Three-year cumulative incidence of biopsy-confirmed, treated acute kidney rejection in the induction and non-induction groups was 19.5% and 27.5% (P =0.14), respectively, with odds 4.6 times greater in African Americans regardless of treatment (P =0.004). Significantly higher rates of cytomegalovirus (CMV) viremia and CMV syndrome occurred in those receiving T-cell-depleting antibody induction (36.1%) when compared with those receiving anti-interleukin-2 receptor antibodies (2%) and non-induction (8.1%) (P <0.0001).

CONCLUSIONS

Tacrolimus, mycophenolate mofetil, and corticosteroids resulted in excellent safety and efficacy in SPK transplant recipients. Actual 3-year kidney survival was significantly better in the induction group; however, CMV viremia and CMV syndrome rates were significantly higher in the T-cell-depleting antibody group. African Americans demonstrated a significantly greater risk of acute rejection despite antibody induction. Decisions regarding the use of induction therapy must weigh the risk of kidney graft loss or rejection against the risk of infection.

Pancreas Transplants: Experience with 232 Percutaneous US-guided Biopsy Procedures in 88 Patients

PURPOSE

To retrospectively assess the authors' experience with percutaneous ultrasonographic (US)-guided biopsy of pancreas transplants.

MATERIALS AND METHODS

Data from 232 percutaneous US-guided pancreas transplant biopsies performed in 88 patients were retrospectively reviewed. Biopsies were typically performed on an outpatient basis by using local anesthesia. Considerations included the indication for the biopsy, the type of pancreas transplant, the number of needle passes, the size of the biopsy needle, the use of aspirin, and the success of the biopsy. Important complications were detailed.

RESULTS

Of the 232 biopsies performed, 78 were for clinically indicated reasons and 154 were for surveillance purposes. The number of biopsy procedures per patient ranged from one to nine (mean, 2.6). Two needle passes were performed in 196 (84.5%) of the biopsy procedures. Almost all biopsies (ie, 228 [98.3%]) were performed by using an 18-gauge biopsy device. Adequate pancreatic tissue was obtained in 223 (96.1%) of the procedures. One hundred sixty-seven biopsies (72.0%) were performed while patients were receiving therapeutic aspirin. Six biopsies (2.6%) resulted in clinically important complications: three cases of intraabdominal hemorrhage and one case each of gross hematuria, allograft pancreatitis, and severe pain requiring overnight hospitalization. Two of the four bleeding complications occurred while patients were receiving therapeutic aspirin.

CONCLUSION

US-guided biopsy of pancreas transplants yielded tissue that was adequate more than 96% of the time. Important complications in this study were few (2.6%) and did not appear to be related to aspirin use.

Decline in native renal function early after bladder-drained pancreas transplantation alone

BACKGROUND

Pancreas transplant alone (PTA) has become accepted therapy for select nonuremic patients with type 1 diabetes mellitus. However, PTA may lead to significant complications including a decline in native renal function. This study examines trends in native renal function during the first posttransplant year in PTA recipients with a spectrum of pretransplant glomerular filtration rates (GFR).

METHODS

Renal function was studied in 23 recipients of bladder-drained PTA who underwent transplantation from April 1998 through September 2001. GFR was measured by corrected iothalamate clearance at the time of transplant evaluation and 1 year posttransplant and also calculated using the Cockcroft-Gault method at the transplant evaluation; at the day of transplantation; and at 1, 6, and 12 months posttransplant.

RESULTS

Iothalamate clearance decreased in the first year in 96% of patients (22 of 23). The mean measured GFR decreased from 84 +/- 33 mL/min/1.73 m2 pretransplant to 52 +/- 26 mL/min/1.73 m2 at 1 year (P <0.001). Calculated creatinine clearance declined in the majority of patients at both 1 and 12 months after PTA, but some patients, including a few with low GFR, maintained stable renal function. Calculated GFR generally correlated well with measured GFR in most patients, with a few notable exceptions. One patient (baseline GFR, 42 mL/min/1.73 m2) developed renal failure in the first year after transplant and required kidney transplantation.

CONCLUSIONS

Bladder-drained PTA results in a decline in native renal function in the majority of patients regardless of the pretransplant GFR. These data suggest the need for strategies to prevent or minimize the decline in renal function after PTA.

Measured and estimated GFR in healthy potential kidney donors

BACKGROUND

Nonradiolabeled iothalamate clearance is an accurate way to determine glomerular filtration rate (GFR). Objectives of this study are to define the normal range of nonradiolabeled iothalamate clearance in potential kidney donors and assess whether creatinine-based GFR estimates are accurate in this population.

METHODS

Medical records of 365 potential kidney donors were reviewed. GFR was measured using clearance of nonradiolabeled iothalamate. Linear regression analysis was used to determine age- and sex-specific normal range values for GFR and serum creatinine. The abbreviated Modification of Diet in Renal Disease (MDRD) and Cockcroft-Gault prediction equations were used to estimate GFR from serum creatinine levels.

RESULTS

GFR declined significantly with increasing age (P < 0.001) and was lower in women than men (P < 0.001). Men at the age of 20 years had an estimated mean GFR of 129 mL/min that declined by 4.6 mL/min/decade. Women at the age of 20 years had a mean GFR of 123 mL/min that declined by 7.1 mL/min/decade. Regression analysis of GFR normalized to body surface area (nGFR) was significant for age (P < 0.001), but not sex (P = 0.826). A 20-year-old had a mean nGFR of 111 mL/min/1.73 m2 that declined by 4.9 mL/min/1.73 m2/decade. Correlation between measured nGFR and estimated GFR was weak (r = 0.26 for abbreviated MDRD equation; r = 0.35 for Cockcroft-Gault equation).

CONCLUSION

This study of nonradiolabeled iothalamate clearance for the measurement of GFR in potential kidney donors established age-adjusted normal values. In healthy individuals, GFR cannot be estimated accurately using the abbreviated MDRD or Cockcroft-Gault prediction equations.

Pancreas-after-kidney transplantation: an increasingly attractive alternative to simultaneous pancreas-kidney transplantation

BACKGROUND

Historically, the clinical acceptability of pancreas-after-kidney (PAK) transplantation has been hampered by relatively high acute rejection rates and lower pancreas graft survival rates when compared with the more commonly performed simultaneous pancreas-kidney (SPK) transplantation. The purpose of this study was to compare PAK transplantation to SPK transplantation in the Thymoglobulin induction era.

METHODS

The authors reviewed all bladder-drained PAK (n=47) transplants receiving rabbit antithymocyte globulin induction from June 1998 to June 2002 and compared them with SPK (n=25) transplants during the same time period at their institution. The authors retrospectively studied data on demographics, patient survival, graft (pancreas and kidney) survival, complications, and biopsy-proven rejection episodes.

RESULTS

The actuarial 1-year patient survival was 93% for the PAK group versus 100% for the SPK group (P =not significant [NS]). The actuarial 1-year pancreas graft survival was 87% for the PAK group versus 92% for the SPK group (P =NS). Waiting time for PAK was significantly shorter than for SPK (6.3 +/- 5.2 vs. 16.2 + -13.7 months, P <0.05). Clinical acute rejection rates were similar in the two groups (4.3% for PAK vs. 4.0% for SPK). PAK recipients demonstrated a greater decline in renal function after transplantation compared with SPK. A multivariate analysis failed to elucidate the cause.

CONCLUSIONS

Newer immunosuppressive regimens allow PAK transplant patients to achieve immunologic outcomes similar to SPK transplant patients. Although the shorter waiting time and the ability to use living-donor kidneys make PAK an increasingly attractive alternative to SPK transplantation, its effect on renal allograft function deserves further attention.

Correlation of quantitative digital image analysis with the glomerular filtration rate in chronic allograft nephropathy

Chronic allograft nephropathy (CAN) is characterized by progressive renal functional loss and histologic abnormalities of one or more tissue compartments. In this study, correlations between histologic abnormalities and graft function [glomerular filtration rate (GFR, measured by iothalamate clearance), serum creatinine (SCr) and urinary protein (UPr)] were investigated using biopsies from 49 patients with newly diagnosed CAN. Extent of tubulointerstitial fibrosis (%TIF), as assessed by a semi-quantitative score, correlated significantly with GFR, SCr and UPr. The close correlation between %TIF and GFR suggested that quantitative measurement of %TIF may predict functional consequences of CAN. Calculation of %TIF by computerized digital analysis was performed using four strategies: (a) quantitation of blue material in Masson's trichrome (MT)-stained sections, (b) quantitation of red material in Sirius Red-stained sections (SR-nonpolarized), (c) quantitation of birefringent material in Sirius Red stained-sections examined under polarized light (SR-polarized) and (d) quantification of brown material in sections stained by immunoperoxidase for alpha-smooth muscle actin. Only the SR-nonpolarized score correlated significantly with GFR at the time of biopsy-diagnosis of CAN. We conclude that digital analysis strategies demonstrate variable accuracy in quantifying %TIF. Validation of the SR-nonpolarized strategy against histologic scoring and GFR supports the application of this technique to longitudinal studies of CAN.

Histologic findings of antibody-mediated rejection in ABO blood-group-incompatible living-donor kidney transplantation

The purpose of this study was to characterize the histology of antibody-mediated rejection (AMR) in ABO blood-group-incompatible (ABOI) kidney transplants as well as on protocol biopsies performed at the time of stable allograft function. Between 5/99 and 1/02, we performed 32 ABOI kidney transplants (13 A2, 19 non-A2 blood-group living donors). Nineteen biopsies were performed for allograft dysfunction, and 127 protocol biopsies were performed 0, 3, 7, 14, 28 days and 3 and 12 months post transplant. Twenty-five of 32 patients have functioning allografts (mean 585 days post transplant). Nine of 32 (28%) developed clinical AMR. Biopsy revealed glomerular thrombi (78%), mesangiolysis (78%), peritubular capillary C4d staining (56%) and neutrophil infiltration (67%), interstitial hemorrhage and necrosis (56%) and arteriolar thrombi (33%). Subclinical AMR was diagnosed by protocol biopsies in four patients. Findings consisted of glomerular thrombi (100%), mesangiolysis (25%), and C4d staining (100%). In late protocol biopsies performed 214-420 days post transplant, mild mesangiolysis was seen in 2/17 (11.7%), and C4d immunostaining was detected in 3/12 (25%). AMR is characterized by glomerular thrombi, mesangiolysis, peritubular capillary neutrophil infiltration interstitial hemorrhage, necrosis, and C4d deposition. Glomerular thrombi appear early in AMR and may appear prior to graft dysfunction.

Plasma exchange conditioning for ABO-incompatible renal transplantation

The supply of deceased donor kidneys is inadequate to meet demand. To expand the pool of potential donors, ABO-incompatible transplants from living donors have been performed. We present the Mayo Clinic experience with such transplants. Enrollment was open to patients when the only available potential living kidney donor was ABO-incompatible. Conditioning consisted of plasma exchanges followed by intravenous immunoglobulin. Splenectomy was performed at the time of transplant surgery. Post-transplant immunosuppression consisted of anti-T lymphocyte antibody, tacrolimus, mycophenolate mofetil, and prednisone. Isoagglutinin titers and scores were determined before and after each plasma exchange. Transplant outcomes were determined. Twenty-six ABO-incompatible transplants were performed. No hyperacute rejection occurred. Mean patient follow-up was 400 days. Patient and graft survivals at last follow-up were 92 and 85%, respectively. Antibody-mediated rejection occurred in 46% and was apparently reversed in 83% by plasma exchange and increased immunosuppression. The initial plasma exchange reduced immediate spin and AHG hemagglutination reactivity scores by 53.5 and 34.6%, respectively. Over the course of the pretransplant plasma exchanges, the immediate spin and AHG hemagglutination reactivity scores decreased by 96.4 and 68.5%, respectively. At 3 and 12 months, the immediate spin and AHG hemagglutinin reactivity scores and titers were less than those at baseline but greater than or equal to those on the day of transplantation. Despite an increase in scores and titers, antibody-mediated rejection was not present. Pre-transplant plasma exchange conditioning combined with other immunosuppressives can be used to prepare patients for ABO-incompatible kidney transplantation from living donors, but antibody-mediated rejection post-transplant is a common occurrence and allograft survival may be reduced. Controlled clinical trials are needed to identify the optimum conditioning for ABO-incompatible renal transplants.

Living-donor kidney transplantation at Mayo Clinic--Rochester

With the established benefits of living-donor kidney transplantation, our primary emphasis at Mayo Clinic, Rochester has been to develop protocols that allow living donation to occur even in the presence of relatively unusual or generally contraindicated situations. This approach has significantly increased the number of patients receiving kidney transplants in the past few years. Our protocols for extended criteria donors and recipients along with the exclusive use of laparoscopic donor nephrectomy have been major contributors to the increase in volume. ABO-incompatible and positive-crossmatch living-donor kidney transplant protocols also have increased the availability of transplants for our patients. Protocol biopsies have aided in the diagnosis of subclinical rejection, polyoma virus and chronic allograft nephropathy. Innovative immunosuppressive protocols such as calcineurin inhibitor-free immunosuppression have decreased rejection and improved both short and long-term renal allograft survival.

Accommodation in ABO-incompatible kidney allografts, a novel mechanism of self-protection against antibody-mediated injury

To elucidate the mechanism of self-protection against anti-donor blood-group antibody known as accommodation, we studied 16 human ABO-incompatible living-donor kidney transplant recipients at 3 and 12 months post transplantation. Both circulating anti-blood-group antibody and the target blood-group antigen in the graft were demonstrable in all patients after transplantation. Thirteen of 16 grafts had normal renal function and histology, while three grafts with prior humoral rejection demonstrated significant glomerulopathy and thus did not meet the criterion for accommodation. Using microarrays, we compared five 1-year protocol ABO-compatible renal graft biopsies to four accommodated ABO-incompatible graft biopsies. Significant alterations in gene expression in 440 probe sets, including SMADs, protein tyrosine kinases, TNF-alpha and Mucin 1 were identified. We verified these changes in gene expression using RT-PCR and immunohistochemistry. Heme oxygenase-1, Bcl-2 and Bcl-xl were not increased in ABO-incompatible grafts at any time-point. We conclude that accommodation is always present in well-functioning, long-surviving ABO-incompatible kidney transplants. This self-protection against antibody-mediated damage may involve several novel mechanisms including the disruption of normal signal transduction, attenuation of cellular adhesion and the prevention of apoptosis.

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.