Immunological monitoring after pancreas transplantation.

PURPOSE OF REVIEW: After switching from bladder to enteric drainage, pancreas graft monitoring, particularly after solitary transplantation, has become an important issue. The aim of this work was to systematically review the relevant literature with regard to various biomarkers, imaging techniques, and pathologic evaluation of allograft tissue.

RECENT FINDINGS: More recent studies including graft histology demonstrate the low specificity of pancreatic enzymes as a marker of acute rejection. On the other hand, most blood and serum markers are indicative of an activated immune status rather than rejection. Interestingly, the concomitantly transplanted kidney from the same donor does not seem to be a reliable surrogate marker. Although computed tomography or ultrasound-guided percutaneous biopsies of the pancreas are performed more frequently at present, the complication rate is still as high as 11%. In contrast, cystoscopic and enteroscopic biopsies of the duodenal part of the graft are associated with almost no complications. The few clinical studies dealing with the duodenum as surrogate marker for the pancreas report a high correlation between duodenum mucosal and pancreas parenchymal histology.

SUMMARY: Pancreatic graft parenchymal biopsy remains the gold standard in diagnosing pancreatic rejection, as clinical parameters, pancreatic enzymes, noninvasive biomarkers, and surrogate renal biopsies are not reliable tools. Endoscopically obtained duodenal cuff biopsies are a less invasive alternative to percutaneous biopsies.