Identification of rat pancreatic duct cells by their expression of cytokeratins 7, 19, and 20 in vivo and after isolation and culture.

Cells from the excretory ducts of the pancreas are thought to be capable of differentiating into exocrine and endocrine cells. To study this in rat models, markers must be found to identify the cells under different experimental conditions. We tested antibodies to different cytokeratins (CKs) by immunocytochemical staining on pancreatic tissue sections from normal rats, after partial pancreatectomy, and after isolation and culture of duct fragments. Monoclonal antibodies to human CK7, CK19, and CK20 were found to react specifically on rat pancreas tissue, as shown by Western blotting. CK20 and CK19 were immunocytochemically detected only in cells of the ductal system, from centroacinar cells to main ducts. CK7 was expressed by islets of Langerhans and by duct cells from main, inter-, and intralobular ducts, but not by centroacinar and terminal duct cells. CKs 7, 19, and 20 were also expressed in proliferating duct cells during tissue regeneration and after isolation and different periods of culture. We conclude that CKs 7, 19, and 20 are very useful markers to study the differentiation of rat duct cells under experimental conditions in vivo and in vitro.