Aims/hypothesis A 41-year-old woman undergoing simultaneous pancreas-kidney transplantation from an HLAmismatched cardiac death donor abruptly developed overt hyperglycaemia under standard immunosuppressive therapy at 48 months after transplantation. Unexpectedly, we found insulitis in the transplanted pancreas and characterised the insulitis. Methods Pancreas graft biopsies were performed 3 years before and after the development of hyperglycaemia and the specimens were examined histologically. Results Insulitis was absent in the first biopsy, although oxidative DNA changes revealed by 8-hydroxy-2′-deoxyguanosine (8-OHdG) staining were diffusely present both in islet cells and exocrine cells. No Ki67-positive proliferating cells were seen in the islets. Anti-glutamic acid decarboxylase antibody was undetectable 6 months earlier but increased to 6.3 U/l at the development of hyperglycaemia. The level of anti-insulinoma- associated protein 2 antibody was 18.5 U/l. Insulin secretion was everely suppressed and insulin therapy was resumed. In the second biopsy, although acute allograft rejection was minimal, insulin-positive beta cells were markedly reduced, and glucagon-positive alpha cells predominated. CD3-positive T lymphocytes, CD8-positive cytotoxic T lymphocytes and CD68-positive macrophages infiltrated around and into islets. The infiltrating cells expressed Fas ligand as well as granzyme B. More than 80% of islets were affected by insulitis. 8-OHdG-positive cells were also present in islets and exocrine tissue. The percentage of Ki67-positive cells in total islet cells was 1.5%. There were no TUNEL-positive apoptotic cells in the islet cells. Conclusions/interpretation The histological features of insulitis in transplanted pancreas were consistent with common type 1 diabetes mellitus, but the clinical course of the recurrence appeared to be more rapid.
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