mainly duct-occluded or enteric-drained pancreas transplants.8 The purpose of this canine study was to determine the sequential histopathologic changes after.
American Journal of Pathology, Vol. 138, No. 2, Februay 1991 Copyight © American Association of Pathologists
Longitudinal Histopathologic Assessment of Rejection After Bladder-drained Canine Pancreas Allograft Transplantation R. D. M. Allen,* J. M. Grierson,* H. Ekberg,t W. J. Hawthorne,t P. Williamson,* S. A. Deane,t J. R. Chapman,* G. J. Stewart,* and J. M. Littlet From the Pancreas Transplant Research Group* and the Department of Surgery, t University of Sydney, Westmead Hospital, Sydney, Australia
In preparation for assessment ofpercutaneous biopsies in our clinical pancreas transplant progratn; a working knowledge of the histopathologic changes after transplantation was obtained in a longitudinal open biopsy study of 16 dogs receiving bladderdrained whole pancreas allografts. Edema, extravasation of polymorphs, and lymphocytes associated with focal parenchymal injury were early, invariable, and probably nonspecific findings. The initial feature of unmodified reyection was the appearance of capillary and small vein endothelial changes with mainly perivascular inflammatory cell infiltration Acinar cell loss occurred early and was progressive, whereas islets and ducts were relatively preserved, indicating that acinar tissue may be more vulnerable to lytic necrosis when damaged Functional reyection; determined by fasting urinary amylase levels was at a stage of extensive and irreversible necrosis. Functioning grafts in immunosuppressed dogs had minor and transient endothelial changes with absence of class H antigen staining ofparenchymal cells. (AmJ
Pathol 1991, 138:303-312)
After more than two decades of development, combined pancreas and kidney transplantation has become a technically viable therapeutic option for diabetics with endstage renal disease.1 The success of the combined procedure has in part been due to the early but implied diagnosis of rejection provided by the concomitant kidney transplant.2 Pancreas rejection, however, has been reported to occur independently of kidney rejection,3 and its presentation can be similar to common clinical prob-
lems of graft pancreatitis and vascular thrombosis. Furthermore serum and urine markers of rejection either occur late or are unreliable and are prone to misinterpretation because of the reluctance of clinicians to perform biopsies on the pancreas allograft. It is therefore of practical importance, particularly if the indications for pancreas transplantation are to be widened to include poorly controlled diabetics before they develop secondary complications, to appreciate the histopathologic changes taking place within the transplanted pancreas and to relate them to commonly used clinical markers of rejection. Histopathologic description of pancreas transplantation is limited to studies on nonimmunosuppressed small animals,45 an assessment in dogs and evaluation in humans of material obtained by cystoscopic transduodenal needle biopsy,67 and a collection of clinical material from mainly duct-occluded or enteric-drained pancreas transplants.8 The purpose of this canine study was to determine the sequential histopathologic changes after transplantation of the whole urinary bladder-drained pancreas, with and without triple immunosuppression, in preparation for the assessment of percutaneous needle core biopsies in our clinical program.
Materials and Methods
Surgical Technique Sixteen outbred dogs, weighing 20 to 25 kg, received vascularized bladder-drained whole pancreas allografts. The pancreas grafts were harvested in continuity with the second part of the duodenum from similar sized outbred dogs, and preserved by ex situ cold flush with isotonic citrate solution. Implantation was performed within 1 hour of harvesting and involved anastomoses of the donor Supported by the National Health and Medical Research Council of Australia, Hoechst Australia Ltd, Kellion Diabetes Foundation Ltd, and Westmead Hospital Research Institute. Accepted for publication September 12,1990. Address reprint requests to Dr. J. M. Gnerson, Institute of Clinical Pathology and Medical Research, Westmead Hospital, Westmead, NSW 2145, Australia.
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portal vein and celiac artery to the right common iliac vessels. A patch of donor duodenum, in continuity with the pancreatic duct, was anastomosed to th dome of the urinary bladder, providing exocrine drainage and the ability to monitor exocrine function by measurement of urinary amylase levels.9 Recipient pancreatectomy was not performed.
Immunosuppression The dogs were alternatively allocated into one of two groups according to immunosuppression received. In group A, 10 dogs received no immunosuppression. In group B, six dogs received triple immunosuppression of cyclosporine given intravenously (5 mg/kg) at the time of transplantation and on days 1 and 2, and thereafter orally (15 mg/kg/day) together with oral azathioprine (2 mg/ kg/day) and oral prednisolone (0.4 mg/kg/day).
Monitoring Allograft Function In the absence of endocrine monitoring, the pancreas allografts were monitored by measurement of amylase concentration in fasting morning samples of urine. Endstage irreversible rejection was defined by urinary amylase (UA) decreasing to a fasting concentration of less than 5000 U/A. This level provided 100% sensitivity for a diagnosis of rejection in an earlier study.10
Histology Technique In all dogs, needle-core (14-gauge) biopsies were taken after direct visualization of the pancreas allograft during limited laparotomies under general anesthesia performed on days 0, 2, 4, 7, 9, 24, 30, or when the dog was killed because of either end-stage rejection (urinary amylase less than 5000 U/L) or intercurrent disease. Multiple pancreatic graft sections were also examined from postmortem specimens, including both pancreatic lobes, vascular pedicles, and any other macroscopically abnormal areas. Biopsies were fixed in Millonig's buffered formalin, and embedded in paraffin wax, serially sectioned, and stained with hematoxylin and eosin (H&E), Gomori trichrome stain (to demonstrate connective tissue), and by immunoperoxidase technique using cross-reacting anti-human monoclonal antibodies directed against insulin and factor Vil (used as a stain for vascular endothelium). Additionally acetone-fixed cryostat sections were stained by an immunoperoxidase technique with the monoclonal antibody ISCR311 directed at murine major histocompatibility complex (MHC) class 11 framework de-
terminants, but also shown to cross-react with dog class II antigens.
Histologic Monitoring The slides were evaluated by an experienced anatomic pathologist (JMG) without knowledge of the immunosuppression group or the time of clinical rejection. Needle core biopsy and autopsy samples were assessed with reference to morphologic areas, structures and staining characteristics within the groupings of interstitial tissue, vessels (lymphatics, capillary, venous, and arterial), acinar cells, islet cells and islets, ductal drainage system, and nerves. The reactive changes within these areas included edema, exudative change, red cell extravasation, inflammatory cell infiltrate (polymorphs, lymphocytes, plasma cells, large undifferentiated immature cells or blasts, and macrophages), cellular degenerations, infiltrating fibroblasts, fibrosis, vessel wall damage, thrombosis, infarction, or other necrosis. A total of 85 features were separately identified and graded as either absent, mild, moderate, or severe. The information was tabulated for each dog by computer and collated to determine the sequential changes associated with unmodified rejection or immunosuppressed functioning grafts. Also included with the variables were numbers to allow the pathologist an assessment of each biopsy for adequacy of size and site and a possible diagnosis. Histologic diagnoses were limited to normal biopsy, minor nonspecific changes, acute pancreatitis, graft infarction, drug toxicity changes, and acute rejection. The immunoperoxidase stains for somatostatin and glucagon proved technically unsatisfactory. No characteristic drug toxicity changes were identified, no obvious graft infections, and no transplanted duodenal patch tissue were encountered.
Results
Survival Seven of the ten dogs in group A, which received no immuno-suppression, were followed until functional rejection (UA < 5000 IU/I), which occurred on days 6, 7, 7, 8, 8, 8, and 13. The remaining three dogs died with functioning grafts on days 4, 4, and 13 of aspiration pneumonitis, early (technical) graft vascular thrombosis, and metabolic acidosis, respectively. Of the six dogs in group B, which received triple immunosuppression, three were healthy with functioning grafts when killed on day 30. The remaining three dogs were unhealthy when killed, one with acute rejection on day 12, and two with severe al-
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lograft pancreatitis on days 7 and 16. There were no complications specifically attributable to the needle core biopsy.
Normal Canine Pancreas The canine pancreas is a bilobed structure with a major and minor pancreatic duct draining into the duodenum separate from the common bile duct. Otherwise both the macroscopic and microscopic appearances closely resemble the human pancreas. Lymph nodes were not found within the pancreas.
Unmodified Rejection Interstitial Changes Edema, not seen in the biopsies taken before transplantation, was an almost invariable finding irrespective of other histologic changes. Expansion of the interstitial tissue with eosinophilic proteinaceous exudate was seen from day 2 in all grafts and contained a minor extravasation of red cells, polymorphs, and lymphocytes. These changes were associated with a mild focal parenchymal injury, identified as both minor and nonspecific (Figure 1). The influx of different cells into the interstitium, according to the day of biopsy, is summarized in Figure 2. Most biopsies taken on day 2 demonstrated a mild infiltration of polymorphs and lymphocytes, with some biopsies additionally containing occasional plasma cells and large immature cells, subsequently confirmed to be blast cells in a concurrent cytology study.12 All biopsies contained these cells by day 4 together with some macrophages and fibroblasts. The grade of cellular infiltrate increased beyond day 4 until graft destruction supervened at a meFigure 1. Pancreati graft biopsy day 2, illustrating minor nonspecific changes of edema, mild inflammatory cell infiltrate, and focal acinar cell vacuolation and necrosis (H&E,
magnification, x30).
of 8 days after transplantation. The anatomic distribution of inflammatory cells was patchy, with polymorphs and macrophages generally found in relationship to necrotic areas, whereas lymphocytes and plasma cells were predominantly perivascular and periductal in distribution. dian
Vascular Changes Capillary and contiguous (small) venous channel changes appeared in parallel, with the initial changes seen in half the grafts by day 2. These changes are best described as 'endothelialitis' comprising prominent swelling of endothelial cells and some intimal mononuclear cell infiltrate together with basement membrane damage and disruption (Figure 3). They were present in all grafts, with one exception, by day 4 and progressed until time of graft destruction. One graft showed extreme changes by day 2 and progressed rapidly to graft destruction by day 6 (Figure 4). Conversely, where these vascular changes appeared later (day 7), graft survival was extended to 13 days without immunosuppression. Changes in small arteries were initially minimal, with some endothelialitis appearing by day 6 and intimal proliferative changes and perivascular infiltrates restricted to relatively longer surviving allografts. The last change observed before graft destruction was the appearance of some small vessel fibrinoid change, venous and arterial intravascular thrombi, and infarction. Autopsy specimens demonstrated only recent thrombosis of the large vessels and total or near total graft infarction (Figure 5). The sequence of vascular changes is summarized in Figure 6. Parenchymal Changes Evidence of acinar cell injury occurred early with cell vacuolation, degranulation, and occasional individual cell
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FIBROSIS NECROSIS MACROPHAGES IMMATURE CELLS FIBROBLASTS PLASMACELLS LYMPHOCYTES POLYMORPHS RED CELLS PROTEIN EXUDATE
EDEMA I
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DAYS AFTER TRANSPLANTATI necrosis seen in the day 2 biopsies. These changes were more extensive by day 4, with some cell group and zonal necrosis seen in association with polymorphs and macrophages. The small zones of necrosis were replaced by fibroblastic tissue. When more extensive, as in the day 7 biopsies, larger areas of soft tissue injury were at least partly replaced by bridging bands of fibroblastic tissue (Figure 7). In contrast, islets demonstrated relatively less injury, with occasional individual cell necrosis not seen until day 4. The majority of islets were still intact on day 7, maintaining positive insulin staining with minimal detectable cellular infiltrate. Both small and large ducts were similarly well preserved with low-grade ductal epithelial proliferation and degeneration seen on day 4. By day 7, a heavy cellular infiltrate surrounded some larger ducts. Necrosis of whole islets and ducts was seen at time of
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Figure 2. Summary of interstitial changes, unmodified by immunosuppression, seen after canine pancreas allograft transplantation (R, rejection).
graft infarction. Parenchymal changes are summarized in Figure 8.
Immunosuppressed Allografts Acute Rejection The fasting urinary amylase level in one dog fell to less than 5000 U/I 8 days after transplantation. This dog subsequently was killed 12 days after transplantation. The sequential biopsies demonstrated changes identical to those in the untreated dogs that developed unmodified rejection.
Functioning Allografts Three grafts with stable exocrine function were followed to the completion of the study at 30 days. For all Figure 3. Graft showing endothelialitis, comprising endothelial cell injury, damage to vessel wall with intimal mononuclear inflammatory cells and associated perivascular infiltrate, and early zonal acinar cell loss. This is the early lesion (H&E, 100). X
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Figure 4. Laterstage endothelialitis involving
capillry venular area associated with extensive local necrosis, inflammatory cell infiltration, and some fibroblastic organization (H&E, x 64).
three grafts, the fasting UA levels remained greater than 10,000 U/I at all times between 9 and 30 days after transplantation, with a mean (± standard deviation [SD]) of 26,700 ± 11,800 U/I on Day 30. The histologic changes are summarized in Figure 8. Early changes on day 2 were similar to those of unmodified rejection, with low-grade interstitial edema, eosinophilic exudate, extravasated red cells, and a mild infiltrate of polymorphs and lymphocytes but no large immature cells. Parenchymal cell injury was similar to that seen in the untreated grafts with acinar cell vacuolation, degranulation, and occasional individual cell necrosis. By day 4, some minor inflammatory cell response was demonstrated comprising large immature cells, plasma cells, fibroblasts, and an increased number of lymphocytes. This infiltrate remained minor and principally perivascular in position with only adjacent acinar cell loss and some fibroblasts present. The vascular response, seen first in the biopsies taken on day 7, was limited to capillary and small vein minor basal membrane disruption and cellular infiltrate. This endothelialitis, toFigure 5. Pancreatic graft demonstrating
progression to late small vessel injury and intravascular thrombosis at time of clinical rejection (H&E, X40).
gether with the interstitial edema, was not seen by the time the day 30 biopsies had been taken. The islets, ducts, and both small and large arteries did not appear to have been affected by transplantation with cover of immunosuppression. The principal change seen in functioning immunosuppressed allografts 30 days after transplantation was a low-grade focal interstitial perivascular mononuclear cell infiltrate with adjacent mild loss of acinar cells (Figure 9). In addition, fine bridging fibrous bands gave the pancreas a vaguely lobulated appearance. The changes seen in functioning immunosuppressed grafts are summarized in Figure 10. Acute Pancreatitis In two immunosuppressed allografts, classical acute pancreatitis was seen preceding and at the time of allograft failure. As generally defined, acute pancreatitis comprises zonal parenchymal necrosis (hemorrhagic or coagulative), rimmed by a zone of leukocytic infiltration (predominantly degenerate polymorphs), and often as-
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* INFARCTION * INTRAVASCULAR THROMBOSIS * ARTERIAL ENDOTHELIALITIS INTIMAL PROLIFERATION FIBRINOID CHANGES
* CAPILLARYVENOUS ENDOTHELIALITIS * PERIVASCULAR INFILTRATE
0
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Figure 6. Summary of vascular changes, un-
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modified by immunosuppression, seen after canine pancreas allograft transplantation (R, reection).
DAYS AFTER TRANSPLANTATIO sociated with external enzymatic fat necrosis. A zone or rim of acute pancreatitis was often identified at the superficial margin of most biopsies in the study. This change was noted as a variable in the study and was not used for the main graft biopsy diagnosis when adequate amounts of deeper biopsy tissue was available. The two dogs with acute pancreatitis at time of death because of deteriorating general condition had progressive biopsy evidence of worsening pancreatitis without evidence of vascular rejection. These changes were diffuse at time of autopsy (Figure 11). The diagnosis of pancreatitis rather than acute rejection was further supported by UA levels consistently more than 15,000 U/I.
Class 11 Antigen Expression Weak endothelial and interstitial cell class 11 expression encountered before transplantation subsequently in-
creased in both immunosuppressed and nonimmunosuppressed grafts, particularly between days 2 and 4. The distribution of staining thereafter remained constant to day 30 in immunosuppressed functioning grafts, whereas the duct epithelium, acinar, and islet cells were all stained by day 4 in the nonimmunosuppressed and rejecting grafts.
Discussion Using the surgical technique and immunosuppression protocol most commonly employed in current clinical pancreas transplantation,13 this canine study has demonstrated early sequential patterns of histopathologic change specific to the pancreas after vascularized allotransplantation. The observed changes were not complicated by deliberate duct occlusion at time of transplantation and further support the current clinical practice of the use of parameters of exocrine function, in preference Figure 7. Pancreatic graft biopsy day 7, with progressing unmodified injury. 7Te changes of vascular endothelialitis, inflammatory infiltrate, parenchymal cell loss, and somefibroblastic organization are seen (H&E, X40).
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* INFARCTIONO
l
* DUCTAL EPITHELIAL NECROSIS * ISLET CELL GROUP NECROSIS * EXTENSIVE ACINAR CELL NECROSIS
* INDIVIDUAL ISLET CELL AND DUCTAL EPITHELIAL CELL NECROSIS *ACINAR CELL GROUP / ZONAL NECROSIS
*ACINAR CELL VACUOLATION, DEGRANULATION & INDIVIDUAL CELL NECROSIS Figure 8. Summary of parenchymal cell changes, unmodified by immunosuppression, seen after canine pancreas allograft transplantation (R, reyection).
to those of islet function, to monitor pancreas allograft rejection. Of practical importance, the study provided histologic standards for subsequent evaluation of percutaneous biopsies in our clinical program. The described histologic changes are, by necessity, trends rather than absolute observations. Interpretation of the histology specimens was limited by the feasibility of frequent open biopsy in a large animal. Furthermore, the small quantity of pancreatic tissue provided by the needle core biopsy limited the assessment of large vessels and ducts. Correlation of the histologic changes with glucose metabolism was not possible, as the dogs were not rendered diabetic before transplantation because of the additional surgical morbidity and impaired cyclosporine absorption associated with native pancreatectomy.14 Nevertheless the surgical model permitted measurement of decreases of UA, a simple marker of end-stage irreversible rejection shown experimentally to occur before raised fasting blood glucose levels.10'15 Figure 9. Immunosuppressed graft day 30,
showing patchy vpbhocytic infiltration and mild local acinar cell loss (H&E, X40).
0 0
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Nonspecific changes attributable to the trauma of donor pancreatectomy, effects of organ preservation by cold perfusion and ice storage, and the transplant procedure are difficult to assess in the absence of an autograft or isograft control group. This unavoidable shortcoming of the study resulted from the need to transplant the whole pancreas with an adjacent duodenal segment. Nevertheless, the presence, at day 2, of interstitial edema, eosinophilic proteinaceous exudate, mild parenchymal cell injury together with mild infiltration of polymorphs, lymphocytes, and red blood cells, were seen both with and without immunosuppression, and were thought most likely to be nonspecific changes in response to injuries sustained during the processes of transplantation. This observation is supported by the resolution of these changes by day 7 in healthy functioning grafts, together with findings of others in canine autografts6 and with enteric drained rat whole pancreas isografts.4 Vascular structural changes, a characteristic feature
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*CAPILLARY - VENOUS ENDOTHELIALITIS
I~~ *INTERSTITIAL PLASMA CELLS & FIBROBLASTS OPERIVASCULAR INFILTRATE
*ACINAR CELL VACUOLATION,DEGRANULATION & NECROSIS *INTERSTITIAL POLYMORPHS & LYMPHOCYTES
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*EDEMA
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Figure 10. Summary of histologic changes
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DAYS AFTER TRANSPLANTATION
of first set rejection in all vascularized solid organ allografts, provide the initial specific histologic evidence of the immune response to the pancreas allograft. The absence of this finding in biopsy specimens reported by Carpenter and colleagues6 in a similar canine study, is difficult to explain other than to suggest that their cystoscopically directed biopsy specimens, taken with an 18gauge needle by modified aspiration technique, may have been inadequate. We have used the term 'endothelialitis' to describe changes principally seen in capillaries and venules and occurring as early as 2 days after transplantation. The early endothelial damage, comprising cell swelling, mononuclear cell infiltrate, and basement membrane disruption, are also described in liver transplantation,16 and in our experience, as with liver, is more pronounced than that seen in renal allografts. The rapidity of appearance, severity, and extent of the endothelialitis and its associated perivascular mononuclear in-
24
30
seen in functioning immunosuppressed canine pancreas allografts after transplantation (R, rejection).
flammatory cell infiltrate, including blast cells, was indicative of the rate of progression of rejection. Early graft loss was signalled by the appearance of small vessel intravascular thrombi. Vasculitis and fibrinoid necrosis of small arteries were mild and late findings, presumably because of the rapidity of graft infarction resulting from small vessel changes. Functional rejection correlated with late histologic rejection and was seen at the stage of extensive necrosis or total graft infarction. Experimental and clinical studies, based on endocrine and exocrine function,5101517 suggest a relative protection of islet tissue from the immune response. In all probability, however, the immune reaction within the parenchymal tissue is evenly directed, with the apparent differential of response resulting from greater vulnerability of acinar cells to damage. The proteolytic enzyme containing acinar cells may be most vulnerable to lytic necrosis, and may therefore self destruct when damaged. Figure 11. Pancreatic graft tissue showing acute pancreatitis (H&E, X40).
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Acinar cell vacuolation, degranulation, and disappearance was a characteristic and progressive result of rejection. Islet and ductal tissue was relatively well preserved until the later stages of graft destruction. This same pattern of injury/tolerance is also seen in many types of chronic pancreatitis. 18 The distribution of ISCR3 staining for MHC class 11 antigens in the rejecting pancreas allograft was generalized, but the significance and exact role of the increased class 11 antigen remains unclear. Lack of specific monoclonal antibodies against canine immune activated cells and polymorphic MHC antigens limits the scope of this and other studies using a canine surgical model. The immune response to immunosuppressed allografts not lost from acute rejection was minor, with transient endothelial changes being the most noticeable finding. One month after transplantation, the characteristic histologic appearance of a functioning pancreas allograft was of a low-grade patchy interstitial perivascular infiltrate with lost adjacent acinar cells replaced by fibrous tissue. Long-term extrapolation of these findings would include further acinar cell loss and more extensive perivascular fibrosis, giving the pancreas allograft a lobulated appearance. In clinical practice, however, episodes of acute rejection are treated and functioning pancreas allografts would therefore provide a wider spectrum of histopathologic change than those encountered in this study. A potential clinical role for biopsy of the pancreas transplant has also been demonstrated by this study. Whereas a concurrent study evaluating fasting UA levels as a marker for canine bladder-drained pancreas allograft rejection provided unacceptably low diagnostic specificity for levels above 5000 U/1,12 a decrease in fasting UA to less than 5000 U/I corresponded in this study to an advanced stage of irreversible morphologic rejection. Early pancreas allograft biopsy, indicated by smaller decreases in UA or recently reported serum markers of rejection,1920 may provide a more sensitive and specific diagnosis of potentially treatable rejection. Equally inappropriate and potentially hazardous anti-rejection treatment, in response to often nonspecific decreases in UA,21 may be avoided. Prompted by this study, an initial clinical assessment of the safety and value of routine and clinically indicated ultrasound-guided percutaneous biopsies of bladder-drained pancreas transplants has been successfully undertaken.22
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References 1. Sutherland DER, Chow SY, Moudry-Munns KC: International Transplant Registry Report-i 988. Clinical Transplantation 1989, 3:129-149 2. Stratta RJ, Sollinger HW, Perlman SB, D'Alessandro AM,
16.
Groshek M, Kalayoglu M, Pirsch JD, Beizer FO: Early diagnosis and treatment of pancreas allograft rejection. Transpl Int 1988,1:6-12 Margrieter R, Klima G, Bosmuller C, KlonigsrainerA, Schmid T, Steiner EL: Rejection of kidney and pancreas after pancreas-kidney transplantation. Diabetes 1989, 38(suppl 1):79-81 Steineger B, Klempnauer J: Distinct histologic patterns of acute, prolonged, and chronic rejection in vascularized rat pancreas allografts. Am J Pathol 1986, 124:253-262 Schulak JA, Drevyanko TF: Experimental pancreas allograft rejection: Correlation between histologic and functional rejection and the efficacy of antirejection therapy. Surgery 1985, 98:330-336 Carpenter HA, Barr D, Marsh CL, Miller AR, Perkins JD: Sequential histopathologic changes in pancreaticoduodenal allograft rejection in dogs. Transplantation 1989,48:764768 Perkins JD, Engen DE, Munn SR, Barr D, March CL, Carpenter HA: The value of cystoscopically-directed biopsy in human pancreaticoduodenal transplantation. Clinical Transplantation 1989, 3:306-315 Sibley RK, Sutherland DE: Pancreas transplantation. An immunohistological and histopathological examination of 100 grafts. Am J Pathol 1987,128:151-170 Deane SA, Ekberg H, Stewart GJ, Grierson JM, Williamson P, Hawthorne WJ, Little JM: Canine whole pancreatic transplantation with exocrine drainage into the bladder. Aust N Z J Surg 1989, 59:659-664 Ekberg H, Dean SA, Allen RD, Hawthorne WJ, Williamson P, Grierson JM, Stewart GJ, Little JM: Monitoring of canine pancreas allograft function with measurements of urinary amylase. Aust N Z J Surg 1988, 58:583-586 Wantabe M, Suzuki T, Taniguchi M, Taniguchi M, Shinohara N. Monoclonal anti-la murine alloantibodies crossreactive with the 1 a-homologues of other mammalian species including humans. Transplantation 1983, 36:712-718 Ekberg H, Allen RD, Greenberg ML, Hawthorne WJ, Earl M, Grierson JM, Williamson P, Deane SA, Stewart GJ, Little JM: Early diagnosis of rejection of canine pancreas allografts by fine-needle aspiration biopsy. Transplantation 1988, 46:485-489 D'Alessandro AM, Sollinger HW, Stratta RJ, Kalayoglu M, Pirsch JD, Belzer FO: Comparison between duodenal button and duodenal segment in pancreas transplantation. Transplantation 1989, 47:120-122 Garvey JFW, Deane SA, Grierson JM, Williamson P, McGill K, Eastman CJ, Duggin GG, Stewart GJ, Little JM: Effect of cyclosporine A on segmental pancreas allografts in the dog. Transplant Proc 1984,16:1043-1045 Powell CS, Lindsey NJ, Nolan MS, Wiley KN, Boyle PF, Herold A, Beck S, Fox M: The value of urinary amylase as a marker of early pancreatic allograft rejection. Transplantation 1987, 43:921-923 Snover DC, Freese DK, Sharp HL, Bloomer JR, Najarian JS, Ascher NL: Liver allograft rejection: An analysis of the use of biopsy in determining outcome of rejection. Am J Surg Pathol 1987, 1 1: 1-10
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17. Prieto M, Sutherland DE, Fernandez-Cruz L, Heil J, Najarian JS: Experimental and clinical experience with urine amylase monitoring for early diagnosis of rejection in pancreas transplantation. Transplantation 1987, 43:73-79 18. Cruickshank AH. Pathology of the Pancreas. Berlin, Springer-Verlag, 1986, p 223 19. Marks WH, Borgstrom A, Sollinger H, Marks C: Serum immunoreactive anodal trypsinogen and urinary amylase as biochemical markers for rejection of clinical whole-organ pancreas allografts having exocrine drainage into the urinary bladder. Transplantation 1990, 49:112-115 20. Perkins JD, Munn SR, Barr D, Fergusson, Carpenter HA:
Evidence that the soluble interleukin 2 receptor level may determine the optimal time for cystoscopically-directed biopsy in pancreaticoduodenal allograft recipients. Transplantation 1990, 49:363-366 21. Munn SR, Engen DE, Barr D, Carpenter HA, Perkins JD: Differential diagnosis of hypoamylasuria in pancreas allograft recipients with urinary exocrine drainage. Transplantation 1990, 49:359-362 22. Allen RD, Wilson TG, Grierson JM, Greenberg ML, Earl M, Stewart JH, Little JM, Chapman JR: Percutaneous pancreas transplant fine needle aspiration and needle core biopsies are useful and safe. Transplant Proc 1990, 22:663-664
