EXPERIMENTAL HYPERACUTE REJECTION IN PANCREAS ALLOTRANSPLANTS

A model of sensitization by intraperitoneal lymph node inoculation was developed to test the hypothesis that hyperacute rejection (HAR) coul d occur in sensitized recipients of vascularized pancreas allografts. Ten pairs of outbred mongrel dogs that were lymphocytotoxic cross-matc h assay negative were inoculated with homogenized lymph nodes on eithe r three or four occasions at fortnightly intervals before renal transp lantation. A renal allograft from the same donor was used to test the HAR response and to further enhance sensitization by rejection of a va scularized organ. Pancreas transplants were performed 2 weeks later, w ith biopsies of the graft and blood samples taken at 0, 10, 20, and 30 min and then at 30-min intervals until the grafts were no longer viab le. All renal and pancreas grafts were rejected in a classical hyperac ute pattern. Within 4 min of revascularization of the pancreas, centra l lobular hemorrhage and vascular congestion appeared, followed by gen eral edema. Histology demonstrated parallel changes of edema, vascular congestion, necrosis, hemorrhage, and leukocytic infiltrate, which al l preceded graft infarction. A sharp decline in both arterial and veno us whit blood cell count and platelets occurred within 10 min of revas cularization with initial sequestration and subsequent release of plat elets from the graft (P=0.02). In summary, HAR of the allografted panc reas can be observed by the surgeon within minutes of revascularizatio n, with predictable macroscopic and microscopic changes. This study su pports the use of routine lymphocytotoxic cross-match tests for all re cipients of pancreas transplants and implies that particular care is w arranted in regraft pancreas allograft recipients.