Pancreatic secretory trypsin inhibitor immunoreactivity detected in serum-free culture medium of human pancreatic carcinoma cell line, CAPAN-1.

Pancreatic secretory trypsin inhibitor (PSTI) immunoreactivity was detected by a radioimmunoassay in a serum-free culture medium conditioned by a human pancreatic adenocarcinoma cell line, CAPAN-1. Its apparent rate of secretion was 280 +/- 20 fg/cell/24 h, and increased in the presence of fetal bovine serum, but was not affected by a cell density at an early stage of culture. This PSTI immunoreactivity was indistinguishable from authentic human pancreatic PSTI on gel filtration, immunoblot analysis and trypsin affinity chromatography.