TRYPSIN(OGEN) CONTENT OF PANCREATIC CALCULI IN CHRONIC CALCIFIED PANCREATITIS IN MAN

Protein analysis of intraductal precipitates and calculi is important to elucidate the mechanism of stone formation in chronic pancreatitis. We revealed human cationic trypsin immunoreactivity in protein extrac ts of pancreatic stones from 11 of 13 patients with chronic calcified pancreatitis, ranging from 0 to 42.3 ng/mu g protein. On gel filtratio n the immunoreactivity eluted as one peak, which is identical to that of human cationic trypsinogen. On immunostaining of pancreatic stone, using an immunogold technic and scanning electron microscopy, the immu noreactivity was observed more densely in the amorphous portion of the center of the stones than in the concentric laminar layer of the peri phery. Only negligible activity was detected for elastase I or amylase in the stone extracts. These results suggest that the presence of try psinogen in pancreatic stoke is not due to coprecipitation or adsorpti on of pancreatic enzymes but that trypsinogen is more likely involved in an initial step of intraductal precipitate formation than in a subs equent step of stone formation. However, the absence of trypsinogen in the stones from two of the 13 patients also suggests that trypsinogen is not the sole protein initiating precipitate formation.