Occluded pancreatic endoprostheses--analysis of the clogging material.

One of the most common late complications of transpapillary pancreatic endoprostheses is clogging of the endoprosthesis lumen. In this study we analysed the morphology and the biochemical nature of the contents of 10 clogged pancreatic endoprostheses. At the optical level the sludge presented as an organic matrix with embedded small quantities of CaCO3 crystals (and in one case CaCO3 microcalculi). Electron microscopy showed the presence of bacterial ghosts and protein threads. The characteristic pattern of proteolysed pancreatic proteins was obtained when the organic matrix was analysed by SDS-Page. The presence of trypsinogen, amylase and one of the molecular secretory forms of Pancreatic Stone Protein (PSP) was confirmed by Western-blotting. PSP was also found in association with CaCO3 crystals by immunolocalization. These results suggest that endoprosthesis clogging is due to the precipitation of whole pancreatic juice protein, probably triggered by uncontrolled proenzyme activation.