Peripancreatic fluid cytology: detection of early rejection versus graft pancreatitis after canine pancreatic transplantation.

Abstract

It is particularly difficult to distinguish between early rejection and graft pancreatitis when early rejection produces an elevated serum amylase level. In this study we determined whether peripancreatic fluid cytology (PFC) can differentiate early acute rejection and graft pancreatitis as an alternative diagnostic tool to graft biopsy that has the potential of pancreatic fistula and hemorrhage. Sixty-two dogs received either a segmental pancreas allograft (n = 25) or autograft (n = 37) heterotopically in the neck. This study included five groups: allografts without immunosuppression (group A, n = 12), allografts with immunosuppression (group B, n = 13), autografts without immunosuppression (group C, n = 11), autografts with immunosuppression (group D, n = 12), and autografts treated by 45 minutes of pretransplant warm ischemia to induce acute graft pancreatitis (group E, n = 14). A closed suction drainage catheter was placed next to the graft to collect peripancreatic fluid daily after the transplant. PFC was performed using May-Gruenwald-Giemsa double-staining technique and compared to the corresponding histology through the observation period. In analyses of 50 functioning grafts, PFC performed on day 1 showed similar neutrophil accumulations in all groups. In sharp contrast, on days 3 and 6, group A had dramatically increased mononuclear cell concentrations in PFC, whereas groups B, C, and D showed significantly lower concentrations, the percent of mononuclear cells among total leukocytes being 47.3 +/- 23.4%, 11.8 +/- 4.9%, 4.3 +/- 1.8%, and 6.4 +/- 2.4% (day 3); and 32.7 +/- 9.8%, 10.5 +/- 4.8%, 7.2 +/- 4.2%, and 8.6 +/- 6.4% (day 6) in groups A, B, C, and D, respectively. On the other hand, in group E numerous degenerating neutrophils with a marked to moderate increase in necrotic tissue fragments were observed by PFC on days 3 and 6. In terms of graft histology on days 3 and 6, group A showed interstitial mononuclear cell infiltration indicating an acute rejection process, whereas groups B, C, and D had minimal inflammatory cell infiltration. In group E graft pancreatitis was histologically confirmed on days 3 and 6. These results suggest that PFC after pancreas transplantation could be a safe, simple, useful diagnostic tool for discriminating early graft rejection from graft pancreatitis.