MORPHOLOGICAL FINDINGS IN DUCT-LIGATED PANCREAS GRAFTS IN THE RAT

Abstract

The morphological findings of duct-ligated pancreas grafts in streptozotocin-induced diabetic hosts were studied using inbred AGUS and WAG rats with a major histocompatibility complex difference. AGUS to AGUS pancreas isografts survived indefinitely. Morphologically, islet tissue was partly dispersed and showed about 75% granulated .beta. cells. Fibrosis was minimal and inflammatory cells generally absent. WAG to AGUS allografts were quickly rejected and showed severe pancreatitis with a polymorphonuclear and mononuclear infiltrate. Islet destruction lagged behind that of exocrine tissue; vascular thrombosis was a late event. In the last group, AGUS recipients 1st received WAG spleen allografts which survived spontaneously. Three to 5 mo. later they were removed and WAG pancreas allografts inserted. Sixty-eight percent of these pancreas allografts survived. Four to 10 mo. later they were characterized by severe fibrosis surrounding islet tissue. Capillaries were always present between islet cells, about 75% of which showed .beta. granules. A mild to moderate mononuclear cell infiltrate and vascular intimal proliferation were also present. Pancreatitis after duct-ligated pancreas allografts apparently is not a sequel of duct ligation but results from rejection and can be prevented with adequate immunosuppression. Fibrosis does not have a detrimental effect on islet cell function as a result of the feasibility of insulin secretion by .beta. cells into adjacent capillaries, and then to larger vessels traversing through the dense fibrosis.