Pancreatic stone protein of pancreatic calculi in chronic calcified pancreatitis in man.

CONTEXT The role of protein components of pancreatic secretions has been controversial in pancreatic stone formation. OBJECTIVE To study the lithogenic role of pancreatic stone protein and lactoferrin in stone formation in chronic pancreatitis. PATIENTS Pancreatic stones were collected from 13 patients with alcoholic (n=6) and nonalcoholic (n=7) chronic calcified pancreatitis. MAIN OUTCOME MEASURES Pancreatic stone extracts were analyzed for pancreatic stone protein and lactoferrin using enzyme immunoassay. The localization of pancreatic stone protein immunoreactivity in the stone was observed using immunogold staining and scanning electron microscopy. RESULTS Immunoreactivities for pancreatic stone protein were detected in the stones from all 13 patients with chronic calcified pancreatitis and for lactoferrin in the stones from five of the 13 patients. Pancreatic stone protein immunoreactivity distributed diffusely from the center to the periphery of the pancreatic stones. CONCLUSIONS Involvement of pancreatic stone protein seems to be constant from the initial step of the stone formation to subsequent steps of the stone growth. However, pancreatic stone protein is only one of the precipitating proteins in pancreatic secretions such as lactoferrin, trypsinogen, etc.