CORRELATION OF REJECTION OF THE DUODENUM WITH REJECTION OF THE PANCREAS IN A PIG MODEL OF PANCREATICODUODENAL TRANSPLANTATION

To assess the correlation of rejection in the duodenum and the pancrea s, we examined pancreatic and duodenal tissue from pancreaticoduodenal transplants in 32 outbred Yorkshire Landrace pigs. After streptozotoc in-induced hyperglycemia, they were transplanted and treated with pred nisone, AZA, and CsA. Immuno-suppression was reduced by 50% weekly and discontinued at 3 weeks. The tissues were harvested at necropsy at va rious time points. Each organ was graded for interstitial rejection an d vascular rejection separately as no, mild, moderate, and severe. All but 1 animal rejected their organs. Complete concordance of rejection between duodenum and pancreas considering both interstitial and vascu lar findings was found in 15/32 (47%) animals. In 11/17 (65%) of the r emaining allografts, the pancreas had a higher rejection grade (3 inte rstitial, 5 vascular, 3 both) and in 6/17 (35%) the duodenum had highe r rejection grades (2 interstitial, 4 vascular). Considering interstit ial and vascular rejection separately, 23/32 (72%) and 20/32 (63%) sho wed concordance, respectively. Most cases (7/9, 78%) of discordant int erstitial rejection showed higher interstitial rejection grades in the pancreas. Five cases (4 pancreas, 1 duodenum) showed interstitial dis cordance of 2 grades or more. Discordant cases with higher vascular re jection were 7 pancreas (58%) and 5 duodenum. Five cases (3 pancreas, 2 duodenum) showed vascular discordance of 2 grades or more. Interstit ial rejection was seen alone (11 cases) and with vascular rejection (2 0 cases), but vascular rejection was never seen alone. We made the fol lowing conclusions. (1) Concordance of duodenal and pancreas rejection occurs in 47% of cases. (2) Discordant cases usually show higher grad es of rejection in the pancreas (65%), but the opposite can also occur . (3) Therefore, if duodenal biopsies are positive, they are likely to be representative of pancreatic pathology, but when negative, they do not rule out rejection of the pancreas. (4) Interstitial rejection ap pears to precede vascular rejection, suggesting that factors released during interstitial rejection play a role in endothelial cell activati on and vascular rejection.