Early detection of rejection in pancreas transplantation

Histologic grading of acute allograft rejection in pancreas needle biopsy: correlation to serum enzymes, glycemia, and response to immunosuppressive treatment

BACKGROUND

Allograft rejection continues to be the most common cause of graft failure in technically successful pancreas transplants. Early diagnosis and treatment of rejection is essential for long-term graft survival. Pancreas graft biopsies are now used routinely for the diagnosis of acute allograft rejection. The correlation between clinical evidence of graft dysfunction (increased serum enzymes and glucose), severity of acute rejection on biopsy (rejection grade), and response to treatment has not been previously studied.

METHODS

A total of 151 pancreas transplant needle biopsy specimens from 57 patients were evaluated. Statistical correlation was done between the histologic rejection grade (O-V) and the peak level of enzymes in serum, glycemia, type of antirejection treatment instituted, and response to treatment. Differentiation between grades was also evaluated statistically.

RESULTS

Response to antirejection treatment was 25%, 40%, 88%, 78%, 50%, and 17% for grades O-V, respectively. The response for grades II and III was better than for grades 0-I and IV-V (P=0.0003 and 0.0008, respectively). The response to corticosteroids alone was 36%, 86%, 68%, and 0% for grades I, II, III, and IV, respectively. The response to antilymphocyte regimen was 50%, 89%, 85%, 71%, and 17% for grades I, II, III, IV, and V, respectively. Overall correlation between the mean levels of enzymes and rejection grade was seen; the increase of lipase was statistically significant (r=0.24, P=0.012). Amylase and lipase correlated very well with each other (r=0.84, P=0.0001). No correlation was found in the mean values of blood glucose with the serum enzyme increase and with severity of rejection. Hyperglycemia was present in 12 patients; this abnormality in patients with grades II-IV responded promptly to treatment, whereas in patients with grade V, hyperglycemia persisted despite antirejection treatment. Other causes of increased enzymes were found in patients with biopsy specimens showing no rejection (grades 0 and I, 43% and 31%, respectively).

CONCLUSIONS

Increased serum enzymes, particularly lipase, correlate with the grade of acute rejection, but their lack of specificity precludes their use as sole markers of acute rejection. Glucose levels are not a sensitive marker for acute rejection. Rejection grades II and III are the most responsive to treatment, and a significant proportion of these cases respond to treatment with corticosteroids only. The higher rejection grades (IV and V) require treatment with antilymphocytic regimens, and their overall response to treatment is moderate to poor, respectively.

Radiologic evaluation of simultaneous pancreas-kidney transplantation

We describe the radiographic imaging modalities that were used in the first twelve consecutive patients who have undergone simultaneous pancreas and kidney transplantation (SPK) at our institution. The total number of examinations undertaken in this study included ultrasound (n = 22), radionucleide scanning (n = 19), cystography (n = 14), computed tomography (n = 2) and magnetic resonance imaging (n = 1). Eighteen percent (5/22) ultrasound examinations were abnormal (perirenal collection [n = 4], peri-pancreatic collection [n = 1]. Two collections required aspiration and were confirmed as lymphocoeles. Cystography showed ureteric reflux in two patients and radionucleide DTPA scanning revealed a delay in the excretory phase in 20% of patients. CT was used in two patients with SPK and demonstrated large peri-pancreatic collections. No episodes of rejection or late graft pancreatitis were noted in this series. We discuss the role of radiographic imaging in detecting early graft failure and also in defining the surgical complications that may arise following transplantation. We also outline the merits and disadvantages of each imaging modality. We conclude that the most useful initial imaging techniques in the evaluation of patients following SPK are ultrasound including Doppler and nuclear medicine.

Pancreas transplantation for diabetes mellitus

Pancreas transplantation has become a viable option for the patient wi th insulin-dependent diabetes mellitus with progressive renal failure. The most common type of pancreas transplantation is a simultaneous pancreas and kidney transplantation performed from a single cadaver donor (SPK). The next most common is pancreas transplantation after successful kidney transplantation (PAK). A few centers are performing pancreas transplantation alone (PTA) in diabetic recipients without renal disease but who have significant complications from their diabetes. Pancreas transplantation is associated with a higher morbidity than kidney transplantation alone. Most pancreas transplantation centers report a significant increase in acute rejection, which can lead to increased hospitalization and risk of opportunistic infection. In addition, the early era of pancreas transplantation was associated with significant surgical complications. However, with bladder drainage of the pancreas exocrine secretions, the surgical complication rate has decreased significantly. Despite medical and surgical complications, the overall results for pancreas transplantation are excellent, with 1 -year graft survival of 75% for SPK transplantations and 48% for PAK and PTA transplant recipients. The effects of a pancreas transplantation on the secondary complications of diabetes have been studied extensively. Most studies have shown a modest improvement in secondary complications with the exception of diabetic retinopathy. The major benefit of pancreas transplantation appears to be enhanced quality of life for patients successfully transplanted. For these reasons, the Kidney-Pancreas Committee of the American Society of Transplant Physicians believes the current results of pancreas-kidney transplantation justify its use as a valid option for insulin-dependent diabetic transplant recipients.

Correlation between cystoscopic biopsy results and hypoamylasuria in bladder-drained pancreas transplants

BACKGROUND

Urinary amylase (UA) remains the most common biochemical parameter to detect rejection in bladder-drained pancreas allografts. With the development of the cystoscopic transduodenal pancreas transplant biopsy technique, tissue samples of the pancreas graft are now frequently obtained. A definitive correlative analysis between UA activity and biopsy results has not been done in the three different pancreas transplant categories (simultaneous pancreas-kidney, pancreas transplant alone, and pancreas after kidney).

METHODS

We studied 66 pancreaticoduodenal biopsy specimens obtained for hypoamylasuria. Rejection was defined as a greater than 25% decrease from stable posttransplantation baseline on two consecutive measurements at least 12 hours apart. To perform biopsies we used our newly developed 14- and 16-gauge core-cut needles (50 cm long). Biopsy specimens were considered positive if either pancreatic or duodenal rejection was found. To assess the quality of UA activity we studied 13 biopsy specimens from patients with stable UA levels; these 13 specimens were negative for rejection.

RESULTS

Acute rejection was diagnosed in 36 biopsy specimens (55%). The mean decrease in UA levels was 67% +/- 8% (range, 28% to 99%) for the positive biopsy results, and 57% +/- 16% (range, 22% to 92%) for the negative biopsy results (p = 0.147). Within 1 month, UA levels returned to baseline in 19% of our patients with positive biopsy results versus 97% with negative results; postbiopsy 1-year graft survival was 64% versus 97% (p < or = 0.05). In assessing the test quality of our biopsy specimens (including 13 obtained for reasons other than hypoamylasuria), we found a sensitivity of 100% (stable UA levels mean no rejection) and a specificity of 30%. The predictive value of a positive test was 53%; of a negative test it was 100%. By performing biopsies we avoided antirejection treatment in 47% of the patients studied. We found no biopsy-related complications.

CONCLUSIONS

Stable UA levels reliably rule out rejection; a decrease is a marker for acute rejection but is unspecific. Performing biopsy is currently the only way to reliably diagnose rejection in solitary pancreas recipients (pancreas transplant alone and pancreas after kidney) and in simultaneous pancreas-kidney recipients with isolated hypoamylasuria. The procedure is safe and should always be attempted to avoid unnecessary rejection treatment.

Pancreas-kidney transplantation for intensivists: perioperative care and complications

Simultaneous pancreas-kidney transplantation is a therapeutic option for type I diabetics with end-stage renal disease. It aims to correct the uremic state, to normalize glucose hemeostasis, and to ameliorate diabetic complications. Careful donor-recipient selection and meticulous intra-operative and postoperative care will substantially impact recipient morbidity. An understanding of the technical aspects of the surgical procedure and its metabolic and immunological consequences is necessary to successfully manage a pancreas-kidney transplant recipient, many of whom are nursed in intensive care units. A successful outcome is predicted in early recognition of technical complications and aggressive management of rejection to achieve the current 1-year graft survival rates of 75% for pancreas transplants and 84% for kidney transplants.

Patient selection for pancreas transplantation

Pancreas transplantation is the only currently available potential cure for type I diabetes. Because of the complications of the procedure and the toxicity of immunosuppression, patients must be carefully selected. The procedure can be justified in patients who already require immunosuppression for a renal allograft. The benefits of improved quality of life and protection from the development of nephropathy in the kidney allograft are significant. Pancreas transplantation alone is harder to justify; the risks of immunosuppression would seem to outweigh the known benefits of normalization of blood glucose. Before pancreas transplantation gains wide acceptance, the graft survival rates must improve. Currently, pancreas graft survival rates are greater than 80% at 1 year, but less than 50% 5 years after the transplantation. Improvement in these rates may occur with the development of more effective and less toxic immunosuppressive agents. Continued improvement in surgical technique should also contribute to overall pancreas transplantation success. Until then, however, pancreas transplantation should be viewed as a therapy for only selected patients in whom the benefits clearly outweigh the risks.

MRI of the pancreas transplant: lack of correlation between imaging and clinical status

Twenty-five MRI scans were performed on 14 patients with cadaveric pancreatic transplants to determine the role of this modality in the evaluation of transplant dysfunction. Our population included 12 normal transplants and 13 recipients with pancreatic graft dysfunction (either rejection or pancreatitis). Six of the latter patients had two or more scans permitting reassessment of the same transplant in various states of health. T1-and T2-weighted MR images were evaluated qualitatively and quantitatively to see if certain patterns were associated with clinical status. We found that although MRI was capable of producing excellent images of the in situ pancreatic transplant, this modality was unable to reliably distinguish the normal from the abnormal transplant. This conclusion differs from prior assessments; possible reasons for this are discussed.