Distribution of pancreatic secretory trypsin inhibitor in various human tissues and its inactivation in the gastric mucosa.

Considerable amounts of immunoreactive pancreatic secretory trypsin inhibitor were detected in lung, stomach, liver, pancreas, kidney, small intestine and ovary. Immunoreactive pancreatic secretory trypsin inhibitor content of surgically removed gastric mucosa was approximately seven times higher than that of gastric mucosa obtained at autopsy. The reduction in PSTI-immunoreactivity seen in a tissue extract of fresh gastric mucosa on 24 hours' incubation represented 9% of the original immunoreactivity in 10 mM Tris-HCl buffer, pH 7.4, at 37 degrees C. While, there was a more than 80% reduction in immunoreactivity on 12 hours' incubation at 37 degrees C at pH 4.0 or under more acidic conditions.