The Wistar Bonn Kobori rat, a unique animal model for autoimmune pancreatitis with extrapancreatic exocrinopathy.

The male Wistar Bonn/Kobori (WBN/Kob) rat is known to be a unique animal model for chronic pancreatitis with widely distributed fibrosis and degeneration of parenchyma because of the infiltration of lymphocytes. In this report, we show that female (but not male) rats develop dacryoadenitis at 3 months of age, and that both male and female WBN/Kob rats develop sialoadenitis, thyroiditis, sclerotic cholangitis and tubulointerstitial nephritis over 18 months of age. The infiltration of CD8+ cells and the deposits of tissue-specific IgG2b were observed in the injured pancreas and lachrymal glands. Furthermore, the number of regulatory T cells (defined as CD4+ Forkhead box P3+ cells) decreased in the periphery of both male and female WBN/Kob rats, suggesting that the onset of these diseases is attributable, at least, to the failure in the maintenance of peripheral immune tolerance. These features show clearly that WBN/Kob rats are a useful animal model for autoimmune pancreatitis and Sjøgren-like syndrome or multi-focal fibrosclerosis in humans. We also show that these autoimmune diseases can be prevented by a newly devised strategy of bone marrow transplantation (BMT) in which bone marrow cells are injected directly into the bone marrow cavity: intrabone marrow-BMT.