The utility of urine cytology in the diagnosis of allograft rejection after combined pancreas-kidney transplantation

A major problem in pancreas transplantation is the lack of a reliable method for the early detection of rejection. Over a 32-month period, we performed 61 combined pancreas-kidney transplants with pancreati-coduodenocystostomy. All patients received quadruple immunosuppression with OKT3 induction. Urine cytologie monitoring was performed on Papanicolaou-stained membrane filters for cell counts and cytocentri-fuge preparations for HLA-DR antigen staining. The final diagnosis of rejection was based on clinical criteria, a rise in serum creatinine, histopathology, and hypoamylasuria. Cytologie features of acute rejection included hypercellularity with lymphocyturia, increased numbers of epithelial cells and positive antibody staining for HLA-DR antigen. A total of 36 definite acute rejection episodes occurred in 28 patients, with 19 confirmed by histopathology. Satisfactory urine cytologie specimens were available in 28 rejection episodes and corroborated the diagnosis in 21 cases, for a sensitivity of 75% compared with 75% and 50% with serum creatinine and urine amylase, respectively. When the urine cytologie score was combined with HLA-DR antigen staining, sensitivity improved to 93%. Thirteen false-positive diagnoses occurred in the remaining 1444 urine cytologie specimens available for evaluation, for a specificity for rejection of 99%. The positive predictive value of cell counts was 62% and negative predictive value was 99%. Patient survival is 98.4%, kidney allograft survival is 96.7%, and pancreas allograft survival is 93.4% after a mean follow-up of 15 months. Only 2 immunologie graft losses occurred (1 kidney, 1 pancreas). In conclusion, urine cytologie monitoring shows promise as a simple, reliable, and noninvasive method to detect rejection after combined pancreas-kidney transplantation with bladder drainage. Prospective studies are needed to assess the role of urine cytologie monitoring after solitary pancreas transplantation.