Pancreatic duct inflammatory infiltration in the nonobese diabetic (NOD) mouse.

The pancreatic duct system during the early stages of type 1 diabetes was examined in 8-wk-old female nonobese diabetic (NOD) mice. Infiltration was seen to involve the smaller ducts while the larger ducts were usually free from ductulitis. The infiltration affected ducts both close to and remote from the islets of Langerhans. In the former situation, infiltration of the islet and that of the duct were not separable. A strong positivity for both Ia and ICAM-1 molecules was observed in all infiltrated ducts, indicating that this infiltrating process is due to the same elements as are involved in the islet inflammation and that also mononuclear cells infiltrating the nonislet ducts express adhesive mechanisms. At the ultrastructural level, endocrine cells that were mainly of the 'closed' type were observed intermingled with the ductular epithelial cells and infiltrating mononuclear cells were detected either in the connective layer or among the epithelial cells of the affected ducts.